ORIGINAL PAPER
Analysis of pharmaceuticals in wastewater and removal using a membrane bioreactor
Jelena Radjenovic&Mira Petrovic&DamiáBarceló
Received:6July2006/Revised:22September2006/Accepted:25September2006/Published online:18November2006 #Springer-Verlag2006
Abstract Much attention has recently been devoted to the life and behaviour of pharmaceuticals in the water cycle.In this study the behaviour of several pharmaceutical products in different therapeutic categories(analgesics and anti-inflammatory drugs,lipid regulators,antibiotics,etc.)was monitored during treatment of wastewater in a laboratory-scale membrane bioreactor(MBR).The results were compared with removal in a conventional activated-sludge (CAS)process in a wastewater-treatment facility.The performance of an MBR was monitored for approximately two months to investigate the long-term operational stability of the system and possible effects of solids retention time on the efficiency of removal of target compounds.Pharmaceuticals were,in general,removed to a greater extent by the MBR integrated system than during the CAS process.For most of the compounds investigated the performance of MBR treatment was better(removal rates>80%)and effluent concentrations of,e.g.,diclofenac, ketoprofen,ranitidine,gemfibrozil,bezafibrate,pravastatin, and ofloxacin were steadier than for the conventional system.Occasionally removal efficiency was very similar, and high,for both treatments(e.g.for ibuprofen,naproxen, acetaminophen,paroxetine,and hydrochlorothiazide).The antiepileptic drug carbamazepine was the most persistent pharmaceutical and it passed through both the MBR and CAS systems untransformed.Because there was no washout of biomass from the reactor,high-quality effluent in terms of chemical oxygen demand(COD),ammonium content(N-NH4),total suspended solids(TSS),and total organic carbon(TOC)was obtained.
Keywords Wastewater treatment.Membrane bioreactor. Conventional activated sludge treatment.Pharmaceuticals. Removal efficiency
Introduction
Most pharmaceutical substances are,by nature,biologically active and hydrophilic,in order that the human body can take them up easily,and persistent,to avoid degradation before they have a curing effect.Depending on the pharmacology of a medical substance it will be excreted as a mixture of metabolites,as unchanged substance,or conjugated with an inactivating compound attached to the molecule[1].When they enter a wastewater-treatment plant,xenobiotics are not usually completely mineralized. They are either partially retained in the sludge,or metabolized to a more hydrophilic but still persistent form and,therefore,pass through the wastewater-treatment plant (WWTP)and end up in the receiving waters.Their removal in WWTPs is variable and depends on the properties of the substance and process conditions(e.g.sludge retention time (SRT),hydraulic retention time(HRT),temperature)[2,3]. Levels of many pharmaceutically active compounds (PhACs)are barely reduced and they are,therefore, detected in WWTP effluents.The presence of PhACs in surface,drinking,and wastewaters is well documented in the literature[1,4–12].Although present at low concen-trations in the environment,drugs can have adverse effects on aquatic organisms.These effects are chronic rather than acutely toxic,and depend on exposure(bioavailability),
Anal Bioanal Chem(2007)387:1365–1377
DOI10.1007/s00216-006-0883-6
J.Radjenovic
:M.Petrovic:D.Barceló
Department of Environmental Chemistry,IIQAB-CSIC,
C/Jordi Girona18-26,
08034Barcelona,Spain
M.Petrovic(*)
Institucio Catalana de Reserca i Estudis Avanzats(ICREA), 08010Barcelona,Spain
e-mail:mpeqam@cid.csic.es
susceptibility to the compound in question,and the degradability of the compound[13].
To ensure compliance with future discharge require-ments,upgrading of existing wastewater-treatment facilities and implementation of new technologies is envisaged as the next step in improvement of wastewater treatment.In the last ten to fifteen years the use of membranes in wastewater reclamation has attracted much interest.Membrane tech-nology has become a technically and economically feasible alternative for water and wastewater treatment,especially because of high SRTs achieved within compact reactor volumes.In the MBR the concentration of microorganisms can be increased to up to20mg L?1.Because of this high biomass concentration the rate of degradation is higher and specialists are grown for problematic compounds.Another advantage of membrane treatment is separation of sus-pended solids by membranes,so they are not limited by the settling characteristics of the sludge.The performance,in terms of effluent quality,is believed to be better,but there is a striking lack of knowledge about the behaviour of trace-pollutants.Literature data on this subject is still very limited and contradictory[2,11,14–16].Ultrafiltration membranes do not enable greater retention of the drugs investigated in this study as a result of filtration effects—the molecular sizes of the compounds selected are at least a factor of100 smaller than the pore size of the membranes.Additional removal of hydrophobic compounds by membranes can, nevertheless,be expected,because they are adsorbed by particles deposited as a layer on the membrane surface;this effect for hydrophilic compounds is not yet very well defined,however[11,17].
The objectives of this work were detection of target pharmaceuticals in wastewater influents and effluents, observation of their elimination in the CAS process,and comparison with results obtained for a laboratory-scale MBR provided with a plate-and-frame submerged mem-brane module.The pharmaceutical products investigated were analgesics and anti-inflammatory drugs(ibuprofen, ketoprofen,naproxen,diclofenac,indomethacin,acetamin-ophen,mefenamic acid,and propyphenazone),lipid regu-lators and cholesterol-lowering statin drugs(clofibric acid, gemfibrozil,bezafibrate,pravastatin,and mevastatin),anti-biotics(erythromycin,azithromycin,sulfamethoxazole, trimethoprim,and ofloxacin),psychiatric drugs(fluoxetine and paroxetine),an antiepileptic drug(carbamazepine),β-blockers(atenolol,sotalol,metoprolol,and propranolol), anti-histaminics(famotidine and loratidine),anti-ulcer agents(lansoprazole and ranitidine),an anti-diabetic (glibenclamide),and a diuretic(hydrochlorothiazide). These compounds had different physicochemical properties (i.e.neutral,ionic,hydrophilic,hydrophobic).Their chem-ical structures and CAS numbers are listed in the Appendix. If their behaviour during wastewater treatment could be more reliably related to process design and operating conditions,process performance could possibly be im-proved by alteration of these conditions in accordance with the types of molecule that are difficult to eliminate. Experimental
Materials and standards
Chemical standards of carbamazepine,lansoprazole,lorati-dine,famotidine,trimethoprim,ofloxacin,atenolol,meto-prolol,azithromycin dihydrate,erythromycin hydrate, fluoxetine hydrochloride,ranitidine hydrochloride,sulfa-methoxazole,propranolol hydrochloride,indomethacin, acetaminophen,mefenamic acid,clofibric acid,bezafibrate, mevastatin,and sotalol hydrochloride were purchased from Sigma–Aldrich(Steinheim,Germany),propyphenazone, pravastatin,and paroxetine hydrochloride from LGC Promochem(London,UK),ketoprofen,diclofenac,gemfi-brozil,ibuprofen,and naproxen from Jescuder(Rubí, Spain),glibenclamide from SIFA Chemicals(Liestal, Switzerland),and hydrochlorothiazide from Pliva(Zagreb, Croatia).All pharmaceutical standards were of high-purity grade(>90%).
Isotopically labelled compounds used as internal stan-dards were13C-Phenacetin,from Sigma–Aldrich,meco-prop-d3,from Dr Ehrenstorfer(Augsburg,Germany),and ibuprofen-d3,atenolol-d7,and carbamazepine-d10from CDN Isotopes(Quebec,Canada).
All solvents(methanol,acetonitrile,and water)were HPLC-grade and were purchased from Merck(Darmstadt, Germany),as also was hydrochloric acid(HCl,37%), ammonium acetate(NH4Ac),and acetic acid(HAc). Nitrogen for drying,purity99.995%,was from Air Liquide (Spain).
Stock solutions of individual standards(1g L?1)and internal standards were prepared in methanol and stored at ?20°C.Stock solutions of ofloxacin,pravastatin,and sulfamethoxazole were renewed monthly because of their limited stability.A standard mixture in which the compounds were at a concentration of approx.20mg L?1was prepared from the stock solutions.Further dilutions of this mixture were prepared in25:75(v/v)methanol–water and were used as working standard solutions.A mixture of internal stan-dards prepared by dilution of individual stock solutions in methanol was used for internal standard calibration.
Membrane bioreactor(MBR)
A submerged MBR of approximately21L active volume equipped with two flat sheet membranes(A4size,area 0.106m2,pore size0.4μm),purchased from Kubota
(Osaka,Japan),was installed in a municipal WWTP in Rubí(Barcelona,Spain).Although the nominal porosity of the membranes was0.4μm(microfiltration)a fouling layer of proteins and microorganisms formed on the surface of the membranes reduced the effective porosity to0.01μm, which brought the type of filtration into the ultrafiltration range[17].
The MBR was operated in parallel with the CAS process (aeration tank and secondary settling tank).The biocenosis of the MBR was grown from inoculated sludge from the municipal WWTP(aeration basin)and cultivated over a period of approximately1month to reach steady-state conditions.The hydraulic retention time was set to14h by regulating the effluent flow and the SRT was infinite, because no sludge was discharged from the reactor.
The laboratory-scale MBR was operated dynamically in intermittent permeation mode—cycles of permeation for 8min interrupted with2min of halt.Influent and permeate flows were controlled by use of flow meters and computer-controlled pumps.Continuous aeration was provided by means of a sparger pipe situated at the bottom of the reaction vessel;the oxygen concentration was kept between 1and2mg L?1.The temperature inside the reactor was 20±2°C throughout sampling.
Wastewater-treatment plant(WWTP)
RubíWWTP was designed for125,550inhabitant equiv-alents.During the sampling programme the WWTP was operating with an average daily flow of22,000m3day?1.A mixture of municipal,hospital,and industrial wastewater is treated.Treatment consists of pretreatment,preliminary treatment,primary sedimentation,and secondary(biologi-cal)treatment.Pretreated wastewater goes through a physical process of settling in a primary clarifier.Secondary treatment occurs in pre-denitrification(anaerobic)and nitrification(aerobic)tanks,and two secondary clarifiers. Secondary sludge is recirculated to a primary clarifier which improves the settling characteristics of the primary sludge and increases sludge age.A mixture of primary and secondary(activated)sludge is processed(thickening, dewatering)and anaerobically digested,and biogas pro-duced is used to heat a digester.The hydraulic retention time of CAS treatment in WWTP Rubí,calculated for the average daily flow,is approximately12h.During the sampling programme the plant was operating with an SRT of approximately3days.WWTP effluent is discharged into the river Riera de Rubí,which flows into the Mediterranean sea. Sampling and sample preparation
Sampling was conducted during May and June,2005. Twenty-eight samples were analyzed.All wastewater samples were taken as time-proportional grab-samples, bearing in mind the HRT of the MBR and CAS processes. The sampling points were:
1.primary sedimentation tank effluent,as the inflow to
the conventional treatment plant and membrane bioreactor,
2.CAS effluent,and
3.MBR effluent.
Wastewater samples were collected,in amber glass bottles pre-rinsed with ultra-pure water,as24-h composite samples;the volume depended on the type of sample (100mL for influent wastewater and200mL for effluent). Immediately on arrival at the laboratory they were filtered through1-μm glass fibre filters and then through0.45μm Nylon membrane filters from Whatman(UK).The target compounds were extracted in one step,by a method described elsewhere[18],using a Baker vacuum system (J.T.Baker,The Netherlands)and Waters(Milford,MA, USA)Oasis HLB cartridges(60mg,3mL)previously conditioned at neutral pH with5mL methanol then5mL Table1MRM transitions of the compounds analyzed
Compound MRM1MRM2MRM3 Ibuprofen205→161
Ketoprofen253→209253→197
Naproxen229→170229→185
Diclofenac294→250294→214
Indomethacin356→297356→255 Acetaminophen152→110152→93
Mefenamic acid240→196240→180 Propyphenazone231→201231→189
Clofibric acid213→127213→85
Gemfibrozil249→121
Bezafibrate360→274360→154
Pravastatin447→327
Mevastatin391→185391→159 Carbamazepine237→194237→192
Fluoxetine310→44310→148
Paroxetine330→192330→123
Lansoprazole370→252370→205
Famotidine338→189338→259
Ranitidine315→176315→130
Loratidine383→337383→267383→259 Erythromycin734.5→158734.5→576.4 Azithromycin749.5→591.4749.5→158 Sulfamethoxazole254→92254→156
Trimethoprim291→230291→261
Ofloxacin362→316
Atenolol267→190267→145
Sotalol273→255273→213
Metoprolol268→133268→159
Propranolol260→166260→183 Hydrochlorothiazide296→269296→205 Glibenclamide494→369
deionised water(HPLC grade).Elution was performed twice with4mL methanol at a flow of1mL min?1.The extracts were then evaporated under a nitrogen stream and reconstituted with1mL25:75(v/v)methanol–water.
Chemical analysis
LC analysis was performed with a Waters(Milford,MA, USA)2690HPLC system coupled to a Micromass Quattro (Manchester,UK)triple quadrupole mass spectrometer equipped with a Z-spray electrospray interface.Chromato-graphic separation was achieved on a Purospher Star RP-18 endcapped column(125mm×2.0mm,particle size5μm) and a C18guard column,both from Merck.
A specific multi-residue analytical method was set up for measurement of the concentrations of the pharmaceutical compounds in wastewaters[18].Analysis was performed in multiple-reaction-monitoring(MRM)mode,in both posi-tive and negative electrospray-ionization mode.This meth-od was refined for analysis of hydrochlorothiazide and glibenclamide.MRM transitions selected for each com-pound are summarized in Table1.In accordance with the performance characteristics defined in EU Commission Decision2002/657/EC for confirmation and identification of pharmaceuticals when using LC–tandem MS as the instrumental technique,a minimum of three identification points are required.When using LC–MS–MS(QqQ) analysis two MRM transitions are sufficient to confirm the identity of a compound.The MRM ratio,calculated as the relationship between the abundances of both transitions and the LC retention time are also criteria used to confirm the presence of an analyte in the samples.In this study, therefore,transitions between a precursor ion and the two most abundant fragment ions were chosen for each analyte when working in MRM mode,resulting in four identifica-tion points,enough to conform with the aforementioned EU
Table2Mean recoveries of the selected compounds and method detection limits(MDL)in ng L?1
Compound Recovery(%)MDL(ng L?1)
Influent MBR effluent CAS effluent Influent MBR and CAS effluent Ibuprofen131(18.1)a68.8(11.0)90.4(11.0)98.020.0
Ketoprofen62.8(2.94)71.3(3.11)59.1(0.897)19074.0
Naproxen49.2(20.0)59.4(1.28)53.4(2.31)79.020.0
Diclofenac83.3(1.17)94.9(10.0)95.0(12.6)16040.0
Indomethacin113(2.95)120(5.63)110(3.78)15031.0 Acetaminophen123(17.0)108(10.5)56.0(7.61)20.9 5.35
Mefenamic acid93.3(1.95)92.1(1.02)91.5(5.29) 5.70 1.85 Propyphenazone60.0(8.00)71.0(4.00)71.0(4.00) 4.80 1.45
Clofibric acid86.0(10.8)104(6.87)74.5(1.40)16.3 3.75
Gemfibrozil91.0(8.47)87.5(1.36)108(17.2)8.70 2.20
Bezafibrate106(3.43)94.4(9.30)89.4(4.62)18.5 4.35
Pravastatin85.6(2.56)78.0(12.2)96.0(19.5)12030.9
Mevastatin103(8.61)134(15.6)123(9.86)9.30 1.30 Carbamazepine84.0(7.84)89.5(5.20)88.0(9.24) 2.200.600
Fluoxetine46.7(2.34)93.7(17.6)59.0(1.60)19.8 1.70
Paroxetine62.2(2.15)109(5.73)71.4(1.49) 3.500.650
Lansoprazole70.0(10.0)87.0(5.00)86.0(4.00)10.9 4.20
Famotidine58.2(7.76)55.4(6.30)66.6(5.39) 3.100.40
Ranitidine41.5(9.85)75.8(14.8)125(11.7) 1.400.300
Loratidine72.6(1.81)78.0(6.97)64.5(4.98)8.00 2.75
Erythromycin67.7(3.15)50.0(13.0)66.6(12.0)12.4 2.00
Azithromycin30.0(7.00)73.0(2.00)63.0(3.00) 1.000.300 Sulfamethoxazole33.7(2.76)95.5(9.24)78.3(1.08)16.1 3.10
Trimethoprim58.8(3.29)128(6.58)60.8(3.87) 1.300.350
Ofloxacin142(19.0)135(5.45)138(4.47)29.37.85
Atenolol83.5(33.8)60.8(10.8)131(15.5) 1.700.750
Sotalol47.1(2.91)31.9(3.05)52.0(3.63) 4.800.700
Metoprolol36.7(1.44)120(2.64)76.7(1.43) 6.30 1.60
Propranolol60.2(0.506)90.8(4.02)70.5(5.27) 2.600.300 Hydrochlorothiazide39.8(7.43)58.9(1.62)73.4(22.9) 4.500.900 Glibenclamide100(11.7)107(10.3)98.5(11.7)19.2 2.30
a The relative standard deviation(%)of the recoveries is given in parentheses(n=3)
directive.When poor fragmentation was observed for the compounds,only one transition could be monitored. Confirmation of the identities of these was achieved by matching their LC retention times with those of standards. Shifts in retention times were less than3%,so the confirmation was regarded as sufficiently reliable.For internal standards only one transition was selected,because they were isotopically labelled compounds unlikely to be found in environmental samples.
To compensate for matrix effects from sample matrices internal standard calibration and adequate dilution of sample extracts were used,on the basis of the previously published method[18].
Recoveries of the method were determined by spiking. Influent samples and CAS and MBR effluents were spiked in triplicate with a standard mixture of selected compounds to a final concentration of1μg L?1.Spiked samples and a blank sample were analysed by the above mentioned method.Recoveries of the target pharmaceuticals are listed in Table2,with method detection limits(MDL)for influent and effluent samples.MDLs and method quantification limits(MQL)were calculated on the basis of signal-to-noise ratios(S/N)of3and10,respectively.
Results and discussion
It is well documented that WWTPs are major contributors of pharmaceuticals in the environment.WWTP Rubímainly receives domestic,hospital,and industrial wastewa-ter and effluent concentrations of several monitored com-pounds exceedμg L?1levels.Ranges of output loads for WWTP Rubi for each pharmaceutical and mean values (g day?1)are reported in Table3.The quantities of pharmaceuticals discharged into the environment are calculated by multiplying the detected effluent concentra-
tions by an average daily flow rate of22,000m3day?1.The total amount of pharmaceutical compounds discharged by WWTP Rubi into the environment exceeded300g day?1 (an average value).The most abundant compounds,with average individual loads of21–56g day?1,were the anti-inflammatory drugs ibuprofen,naproxen,and diclofenac, the lipid regulators gemfibrozil and bezafibrate,the diuretic hydrochlorothiazide,and theβ-blocker atenolol.
To assess the efficiency of elimination by the MBR, substance-specific analysis must be performed and the bulk properties DOC and COD of wastewater influents and effluents must also be determined.The performance of the MBR system is summarized in Table4.The data are presented for the sampling period.Removal efficiencies of 98.7%for TSS and90.4%for total COD were achieved during the membrane process.Average effluent ammonia concentration was1.01μg L?1in the MBR effluent,com-pared with48.41μg L?1in the CAS effluent.It is known that membrane processes are quite efficient at removing COD and TOC from wastewater[19,20].Improved COD removal is attributed to the combination of complete retention of particulate material by the membrane,including suspended COD and high molecular weight organisms,and to avoidance of biomass washout problems common in activated sludge systems.Consequently,stable conditions are provided for growth of specialized microorganisms which are the able to remove poorly biodegradable components.
Of31pharmaceutical products included in the analytical method,22were detected in the wastewater entering WWTP Rubí.Box plots of measured concentrations of each pharmaceutical are showed in Figs.1,2and3.Ten measured values are given for influent and MBR effluent concentrations and eight for CAS effluent(data are missing Table3Average daily output loads of the investigated pharmaceu-ticals for RubíWWTP
Pharmaceutical Effluent load(g day?1)
Mean Range Analgesics and anti-inflammatory drugs
Naproxen37.010.8–76.9 Ketoprofen17.111.4–36.3 Ibuprofen56.37.39–137.9 Diclofenac27.317.3–43.8 Indomethacin 1.93nd–2.73 Acetaminophen 4.55 1.06–9.2 Mefenamic acid0.440.27–0.85 Propyphenazone0.680.43–0.96 Anti-ulcer agent
Ranitidine 2.770.55-5.30 Psychiatric drug
Paroxetine0.08nd a–0.16 Antiepileptic drug
Carbamazepine 5.21 1.44-6.71 Antibiotics
Ofloxacin 6.93 2.40–11.2 Sulfamethoxazole 3.06 1.42–5.81 Erythromycin 2.290.95–4.51
β-blockers
Atenolol21.07.70–33.2 Metoprolol 3.32 1.14–5.43 Diuretic
Hydrochlorothiazide33.721.2–46.0 Hypoglycaemic agent
Glibenclamide0.74nd–0.98 Lipid regulator and cholesterol lowering statin drugs
Gemfibrozil54.330.1–73.9 Bezafibrate21.610.9–50.8 Clofibric acid 1.750.40–3.43 Pravastatin nd nd
a Not detectable(below the LOQ)
for two sampling programmes).For each variable the box has lines at the lower quartile(25%),median(50%),and upper quartile(75%)values.The whiskers are the lines extending from each end of the box to show the extent of the data up to 1.5times the interquartile range(IQR). Outliers are marked with+symbols.
The highest influent concentrations(μg L?1)were measured for the analgesics and anti-inflammatory drugs naproxen,ibuprofen,ketoprofen,diclofenac,and acetamin-ophen,the antihyperlipoproteinaemic drugs gemfibrozil and bezafibrate,theβ-blocker atenolol,and the diuretic hydrochlorothiazide.For other compounds input concen-trations were usually in the range10–100ng L?1.Because the low concentrations measured were sometimes close to the limits of quantification,any hypothesis about the efficiency of their elimination is questionable.Mean removal was,nevertheless,calculated for each of the pharmaceutical compounds;the results are presented in Table5.The most important removal pathways of organic compounds during wastewater treatment are:
1.biotransformation/biodegradation,
2.adsorption by the sludge(excess sludge removal),and
3.stripping by aeration(volatilization).
Because of the low values of the Henry coefficients(K H) of the compounds investigated[21],the fraction removed by volatilization can be neglected[16].The two processes abiotic(adsorption)and biotic degradation(transformation by microorganisms)could not be distinguished,because no method was developed for analysis of the target compounds in sludge.The term“removal”is therefore used here for conversion of a micropollutant to compounds other than the parent compound.
Elimination efficiency of the laboratory-scale MBR and the full-scale CAS process was comparable for naproxen, ibuprofen,acetaminophen,hydrochlorothiazide,and parox-etine.All were removed to a large extent by both systems (removal was greater than80%except for hydrochlorothi-azide,for which it was between56and85%).Hydrochlo-rothiazide and paroxetine were eliminated slightly better by conventional treatment.Similar results for the behaviour of these drugs during conventional treatment have been reported by several authors[2,3,9,11].
For ketoprofen,diclofenac,bezafibrate,and gemfibrozil removal by the MBR system was very high and uniform (>90%),with the exception of two sampling programme.It is assumed this variation could have been a result of reduced microbial activity or altered sorption and floccula-tion conditions.No plausible explanation can be given for the drastically reduced efficiency of removal of clofibric and mefenamic acid by MBR in two sampling programmes; otherwise these were eliminated with efficiencies between 65and90%.High and steady removal(>80%)in the MBR was also observed for ranitidine and ofloxacin.In conven-tional treatment all these pharmaceuticals were eliminated with a wide range of efficiencies,always lower than those obtained by the MBR.Better removal of readily biode-gradable micropollutants by the MBR could be because of the smaller flock size of the sludge,which enhances mass transfer by diffusion and therefore increases elimination. Taking into consideration the composition of sludge originating from a membrane bioreactor(specialized micro-organisms,large amount of active biomass in suspended solids)improved removal is to be expected;this was confirmed by our experiments.
A possible explanation of substantially greater attenua-tion of diclofenac by the MBR(average removal efficiency 87%compared with50%in CAS)could be the greater age of the MBR sludge.Improved removal is observed with increasing solids retention time[14].Another explanation could be greater adsorption potential of the MBR sludge, because the organic matter content is greater than for CAS sludge.According to results from the EU project Poseidon [22],adsorption processes affect elimination of diclofenac. Literature data on this matter is still very contradictory. Clara et al.reported poor removal of diclofenac in laboratory-scale WWTPs whereas in full-scale plants removal varied from less than20%to between60and 80%for some of the facilities investigated[2].Heberer et al.[7]reported low removal efficiencies in a WWTP whereas Ternes et al.documented significant(69%) elimination of diclofenac[8].
Removal of carbamazepine was,in contrast,very poor (<20%),and effluent concentrations for both MBR and CAS were frequently greater than influent levels.Poor elimination of this neutral drug has been reported by many authors[9,11,23,24].Glucuronide conjugates of carba-
Table4Summary of the per-formance of the MBR system a Values are averages from
n=16samples,with standard deviations in parentheses Property Influent MBR effluent CAS effluent TSS(mg L?1)119.2(17.37)a 1.600(1.770)26.72(15.69) COD total(mg L?1)508.2(124.3)48.58(22.47)111.6(53.35) TOC(mg L?1)67.67(24.29)10.89(3.470)27.33(13.75) N-NH4(mg L?1)49.13(15.79) 1.010(0.4200)48.41(12.87) pH7.52(0.300)7.08(0.270)7.63(0.160)
1
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Fig.1Removal,during MBR and CAS treatment,of the analgesics and anti-inflammatory drugs naproxen (a ),ketoprofen (b ),ibuprofen (c ),mefenamic acid (d ),diclofenac (e ),indomethacin (f ),acetaminophen (g ),and propyphenazone (h )
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mazepine can,presumably,be cleaved in sewage,thus increasing environmental concentrations [8].
Rates of removal of the antibiotic sulfamethoxazole were very variable in both treatments investigated.According to Drillia et al.its microbial degradation will depend on the
presence of readily biodegradable organic matter in wastewater;this varies during both MBR and CAS treatment [25].Also,a substantial amount of sulfamethox-azole enters WWTPs as its human metabolite N 4-acetylsul-famethoxazole,which can possibly be converted back to the original compound during treatment [26].
Efficiency of removal of atenolol,metoprolol,pravastatin,erythromycin,and indomethacin varied in both MBR and CAS treatment.This could not be explained.Fluctuation of elimination efficiency was also observed for propyphenazone
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200
250
d)
50100
150200250
300350
400
e)
1
23
456
7
8910
HYDROCHLOROTHIAZIDE
influent
MBR effluent
CAS effluent
f)
10
20
30405060
7080c (μg /L )
c (n g /L )
c (μg /L )
c (n g /L )
c (n g /L )
c (μg /L )
Fig.3Removal during MBR and CAS treatment of the lipid regulator and cholesterol-lowering statin drugs gemfibrozil (a ),bezafibrate (b ),clofibric acid (c ),and pravastatin (d ),the diuretic hydrochlorothiazide (e ),and the hypoglycaemic agent glibenclamide (f )
Fig.2
Removal during MBR and CAS treatment of the antibiotics
ofloxacin (a ),sulfamethoxazole (b ),and erythromycin (c ),the β-blockers atenolol (d )and metoprolol (e ),the anti-ulcer agent ranitidine (f ),the antiepileptic drug carbamazepine (g ),and the psychiatric drug paroxetine (h )
(44.8–82.9%for MBR and 6.82–62.6%for CAS)and glibenclamide(14.8–73.7%for MBR and11.9–79.7%for CAS).
Effluent concentrations greater than those recorded for the influent could be explained by the presence of input conjugate compounds that are transformed into the original compounds during treatment.Because these conjugates were not included in the analysis,no firm conclusion can be made about their biotransformation,especially because sampling inaccuracy can also lead to errors.
Conclusion
Several pharmaceutical products(e.g.ibuprofen,naproxen, acetaminophen,ketoprofen,diclofenac,bezafibrate,gemfi-brozil,ranitidine,ofloxacin,hydrochlorothiazide,and parox-etine)with high rates of attenuation can be expected to be completely removed from wastewater by adsorption or degradation,or a combination of both,during membrane treatment.For most of the compounds investigated MBR effluent concentrations were significantly lower than in the effluent from conventional treatment.Elimination of hydro-chlorothiazide and paroxetine was slightly better in CAS treatment.Some substances(e.g.carbamazepine)were not removed by either MBR or CAS treatment.No relationship was found between the structures of target compounds and their removal during wastewater treatment,however.The range of variation of the efficiency of removal by the MBR system was small for most of the compounds;in conven-tional treatment greater fluctuations were observed and removal efficiency was found to be much more sensitive to changes in operating conditions(temperature,flow rate,etc).
Although membrane technology seems a promising means of removal of pharmaceutical compounds,the MBR process investigated would not completely halt discharge of micropollutants.Membrane treatment process-es should be optimized by modification of the membranes (variation of the materials and reduction of molecular mass cut-off limits)and/or by modification of the treatment process(inoculation of special microorganisms).The efficiencies of diverse microbial populations in elimination of selected pharmaceuticals,and optimization of design and operating conditions of a laboratory-scale MBR will be the main objectives of our future investigations.That would provide guidelines for scale-up of a biological pilot plant and its evaluation by integration into an industrial process water-recycling system.Because of the current lack of information on the behaviour of pharmaceuticals in surface and wastewaters,however,further studies are required on the occurrence,fate,and effects of these substances in the environment.
Acknowledgements The study was supported financially by the European Union EMCO project(INCO-CT-2004-509188)and by the Spanish Ministry of Education and Science project EVITA (CTM2004-06255-CO3-01-A)and by the project CTM2005-24254-E. J.R.gratefully acknowledges the I3P Program(Itinerario integrado de inserción profesional),co-financed by CSIC(Consejo Superior de Investigaciones Científicas)and European Social Funds,for a predoc-toral grant.Waters(Milford,USA)is gratefully acknowledged for providing the SPE cartridges and Merck(Darmstadt,Germany)for providing the HPLC columns.Hydrochlorothiazide and glibenclamide were kindly supplied by Dr M.Ahel(Centre for Marine and Environmental Research,Zagreb,Croatia).
Appendix
Structure and CAS numbers of the pharmaceutical products studied.
Table5Mean removal of selected pharmaceuticals by the MBR and CAS processes
Compound Elimination(%)in:
MBR a CAS b Analgesics and anti-inflammatory drugs
Naproxen99.3(1.52)85.1(11.4) Ketoprofen91.9(6.55)51.5(22.9) Ibuprofen99.8(0.386)82.5(15.8) Diclofenac87.4(14.1)50.1(20.1) Indomethacin46.6(23.2)23.4(22.3) Acetaminophen99.6(0.299)98.4(1.72) Mefenamic acid74.8(20.1)29.4(32.3) Propyphenazone64.6(13.3)42.7(19.0) Anti-ulcer agents
Ranitidine95.0(3.74)42.2(47.0) Psychiatric drugs
Paroxetine89.7(6.69)90.6(4.74) Antiepileptic drugs
Carbamazepine No elimination c No elimination Antibiotics
Ofloxacin94.0(6.51)23.8(23.5) Sulfamethoxazole60.5(33.9)55.6(35.4) Erythromycin67.3(16.1)23.8(29.2)
B-blockers
Atenolol65.5(36.2)No elimination Metoprolol58.7(72.8)No elimination Diuretics
Hydrochlorothiazide66.3(7.79)76.3(6.85) Hypoglycaemic agents
Glibenclamide47.3(20.1)44.5(19.1) Lipid regulator and cholesterol lowering statin drugs
Gemfibrozil89.6(23.3)38.8(16.9) Bezafibrate95.8(8.66)48.4(33.8) Clofibric acid71.8(30.9)27.7(46.9) Pravastatin90.8(13.2)61.8(23.6)
a,b Values are averages,with relative standard deviations(%)in parentheses,for n=10a or n=8b samples
c Compounds were classifie
d as“no elimination”if elimination was less than10%
Compound
CAS number Compound
CAS number
CH 3
COOH
CH 3
C
H 315687-27-1
CH 3
C H 3O
CH 3
COOH
C
H 325812-30-0
Ibu p rofen
Gemfibrozil
CH 3
COOH
O
22071-15-4
NH
O
COOH CH 3
C
H 3O
Cl
41859-67-0
Keto p rofen
Bezafibrate
CH 3
COOH
H 3C O
22204-53-1
N
NH 2
O
298-46-4
Naproxen
Carbamazepine
Cl
Cl
NH
COOH
15307-86-5 NH
CH 3
CH 3
COOH
61-68-7
Diclofenac Mefenamic acid
N
CH 3
Cl
COOH
OH 3C
O 53-86-1
O
O
O
N
H
F
110429-35-1
Indomethacin
Paroxetine
NH
CH 3
O O
H 103-90-2
N
S
O
O
NH
CH 3
O
N
H 2723-46-6
Acetamino p hen
Sulfamethoxazole
N
N CH 3
C
H 3C
H 3O
CH 3
479-92-5 S
NH
N
H S O
O
Cl
O
O
N
H 258-93-5
Pro p y p henazone Hydrochlorothiazide
Cl
O
COOH
C
H 3CH 3
882-09-7
H 3C O
O NH
CH 3
CH 3
OH
37350-58-6
Clofibric acid
Metoprolol
O
C
H 3O
CH 3
O
H HOOC
O
H OH
CH 3
81093-37-0 N
N
N
C
H 3O
CH 3
O
COOH
F
82419-36-1
Pravastatin
Ofloxacin
Continuation of Appendix
C
H 3CH 3
NH
O
NH 2
O
OH
29122-68-7 C
H 3N CH 3
O
S
NH
NH
CH 3
NO 2
66357-59-3
Atenolol Ranitidine
O
CH 3
O
H N
CH 3
C
H 3O
O O
O
OH
O H O
C
H 3CH 3
C H 3CH 3CH 3
CH 3 CH 2
OH
C
H 3O
H 3CO
CH 3
OH
CH 3
114-07-8N
O
CH 3
O
H N
CH 3
C
H 3O
O
O
O
OH
O H C
H 3CH 3
C H 3CH 3
CH 3
CH 3 CH 2OH
C
H 3O
H 3CO
CH 3
OH
CH 3
CH 3117772-70-0
Erythromycin Azithromycin
OCH 3
H 3CO
H 3CO
N
N
NH 2
NH 2
738-70-5F 3 C
NH
CH 3
O
59333-67-4
Trimetho rim Fluoxetine
O
NH
OH
CH 3
CH 3
C
H 33506-09-0
N
H 2NH 2
N
N
S
S
N
S
NH 2
NH 2
O O 76824-35-6
Propranolol
Famotidine
N
N
O
CH 3
O
Cl
79794-75-5CH 3
O
O
O
CH 3
C H 3O O
H 73573-88-3
Loratidine Mevastatin
N
H N
S
N
O
CF 3
O
C H 3103577-45-3 NH
S
C
H 3O
O NH
CH 3
CH 3
OH
959-24-0
Lanso razole Sotalol
NH
S
NH
NH OCH 3
Cl
O
O O
O
10238-21-8
Glibenclamide
References
1.Halling-S?rensen B,Nors Nielsen S,Lanzky PF,Ingerslev F,
Holten Lutzh?ft HC,J?rgensen SE(1998)Chemosphere36:357–393
2.Clara M,Kreuzinger N,Strenn B,Gans O,Kroiss H(2005)Water
Res39:97–106
3.Vieno NM,Tuhkanen T,Kronberg L(2005)Environ Sci Technol
39:8220–8226
4.Petrovic M,Gonzalez S,Barcelo D(2003)Trends Anal Chem
22:685–696
5.Kolpin DW,Furlong ET,Meyer MT,Thurman EM,Zaugg SD,
Barber LB,Buxton HT(2002)Environ Sci Technol36:1202–1211
6.Buser HR,Poiger T,Muller MD(1999)Environ Sci Technol
33:2529–2535
7.Heberer T(2002)Toxicol Lett131:5–17
8.Ternes TA(1998)Water Res32:3245–3260
9.Metcalfe CD,Koenig BG,Bennie DT,Servos M,Ternes TA,
Hirsch R(2003)Environ Toxicol Chem22:2872–2880
10.Castiglioni S,Bagnati R,Fanelli R,Pomati F,Calamari D,
Zuccato E(2006)Environ Sci Technol40:357–363
11.Joss A,Keller E,Alder AC,G?bel A,McArdell CS,Ternes T,
Siegrist H(2005)Water Res39:3139–315212.Giger W,Alder AC,Golet EM,Kohler HPE,McArdell CS,
Molnar E,Siegrist H,Suter MJF(2003)Chimia57:485–491
13.Jjemba PK(2006)Ecotoxicol Environ Saf63:113–130
14.Clara M,Strenn B,Kreuzinger N,Kroiss H,Gans O,Martinez E
(2005)Water Res39:4797–4807
15.Quintana JB,Weiss S,Reemtsma T(2005)Water Res39:2654–
2664
16.Joss A,Zabczynski S,Gobel A,Hoffmann B,Loffler D,McArdell
CS,Ternes TA,Thomsen A,Siegrist H(2006)Water Res 40:1686–1696
17.Urase T,Kagawa C,Kikuta T(2005)Desalination178:107–113
18.Gross M,Petrovic M,Barcelo D(2006)Talanta,in press
19.Xing CH,Tardieu E,Qian Y,Wen XH(2000)J Membr Sci
177:73–82
20.Cicek N,Wiennen H,Suidan MT,Wrenn BE,Urbain V,Manem J
(1998)Water Res32:1553–1563
21.https://www.doczj.com/doc/f615853239.html,/
22.http://poseidon.bafg.de/
23.Strenn B,Clara M,Gans O,Kreuzinger N(2004)Water Sci
Technol50:269–276
24.Clara M,Strenn B,Kreuzinger N(2004)Water Res38:947–954
25.Drillia P,Dokianakis SN,Fountoulakis MS,Kornaros M,
Stamatelatou K,Lyberatos G(2005)J Hazard Mater122:259–265 26.Gobel AMCS,Suter MJF,Giger W(2004)Anal Chem76:4756–
4764
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糖厂制糖污水处理工程设计-文献综述 本科毕业设计论文 论文综述 文献综述 目录 1.前言1 2. 制糖废水的来源和水质 1 3. 制糖废水处理研究的历史 2 4. 制糖废水处理常用的工艺 2 4.1厌氧处理 2 4.2 好氧处理 4 4.3 土地处理 4 5. 适合本设计工艺 5 5.1 工艺的选择 5 5.2 工艺流程图及描述6 6. 结语7 参考文献8 前言 水是生命之源,是人类和其它一切生物生存和发展的物质基础,又是社会经济发展重要而宝贵的资源。随着经济的发展和人口的增长,水资源的短缺已成
为当代社会突出的环境问题。 目前我国有60%以上的水源用于农业,工业用水约占20% ,主要工业产品的平均用水量比发达国家高几十倍甚至上百倍,不仅加剧了用水的紧张,而且产生大量污水污染环境。根据国家环保总局发布的“2002年全国环境统计公报”显示,2002年,全国废水排放总量为439.5亿吨,比上年增加1.5%。其中工业废水排放量207.2亿吨,占废水排放总量的47.1%;废水化学需氧量CODcr排放量1367万吨,其中工业废水中化学需氧量排放量584万吨,占化学需氧量排放总量的42.7%[1]。重金属、砷、氰化物、挥发酚等的排放量也呈上升趋势。 目前制糖废水的治理主要采用物化法和生化法。用物化法对废水进行预处理,然后再进入生化系统,最后依次经物化处理及生物滤池后达标排放。物化法处理包括:沉淀法,吸附法,电化学法。磁分离法,高级氧化法,蒸发浓缩法等。制糖废水的可生化性好,因此国内外对此废水的处理常采用生化法。主要有厌氧处理法UASB法、二段厌氧法、厌氧一好氧处理法、厌氧一光合细菌处理法等。 2. 制糖废水的来源和水质 制糖废水包括生产废水和糖蜜酒精废水两部分。生产废水是指以甜菜和甘蔗为原料加工生产蔗糖过程中产生的废水,一般为中、低浓度废水,包括洗涤流送水、冷凝冷却水、滤泥水、压粕水、洗滤布水亚法糖厂等。糖蜜酒精废水是指以制糖副产品一糖蜜为原料,发酵生产酒精过程中产生的高浓度有机废水。此类废水水量大,每生产1吨酒精约产生7~15吨废水,而且污染物浓度高,含有糖、蛋白质、氨基酸、维生素等有机物以及N、P、K、Ca、Mg等无机盐和较高浓度SO42-。此类废水大多呈酸性,而且色度高,类黑色索等难以降解。这些废水若直接排放会造成水体富营养化、缺氧、鱼虾绝迹、水质恶化、发臭,严重污染地表地
丹宁改性絮凝剂处理城市污水 J.Beltrán-heredia，J.ánche z-Martin 埃斯特雷马杜拉大学化学工程系和物理化学系,德埃娃儿，S / N 06071，巴达霍斯，西班牙 摘要 一种新的以丹宁为主要成分的混凝剂和絮凝剂已经过测试用以处理城市污水。TANFLOC 证实了其在浊度的去除上的高效性（接近100%，取决于剂量），并且近50%的BOD5和COD 被去除，表明TANFLOC是合适的凝集剂，效力可与明矾相媲美。混凝絮凝剂过程不依赖于温度，发现最佳搅拌速度和时间为40转/每分钟和30分钟。多酚含量不显著增加，30%的阴离子表面活性剂被去除。沉淀过程似乎是一种絮凝分离，所以污泥体积指数和它随絮凝剂剂量的改变可以确定。证明TANFLOC是相当有效的可用于污水处理的混凝絮凝剂。 关键词: 基于丹宁的絮凝剂城市污水絮凝天然混凝剂 1．简介 人类活动是废物的来源。特别是在城市定居点，来自家庭和工业的废水可能是危险有害的产品[ 1 ]，需要适当的处理，以避免对环境[ 2 ]和健康的影响[ 3,4 ]。2006年12月4日联合国大会通过决议宣布2008为国际卫生年。无效的卫生基础设施促使每年220万人死于腹泻，主要在3岁以下儿童，600万人因沙眼失明，两亿人感染血吸虫病，只是为了给出一些数据[ 5 ]。显然，他们中的大多数都是在发展中国家，所以谈及城市污水，必须研究适当的技术来拓宽可能的处理技术种类。 在这个意义上，许多类型的水处理被使用。他们之间的分歧在于经济和技术特点上。了摆脱危险的污染[ 6 ]，一些令人关注的论文已经发表的关于城市污水处理的几种天然的替代方法，包括绿色过滤器、化学初步分离、紫外消毒[ 7 ]和多级程序[ 8 ]。 几个以前的文件指出了城市污水管理[9,10]的重要性。这种类型的废物已成为社会研究的目标，因为它涉及到几个方面，都与社会结构和社会组织[11 ]相关。根据这一维度，必须认识到废水管理作为发展中国家的一种社会变化的因素，事关污水处理和生产之间的平衡，是非常重要的，一方面，人类要发展，另一方面，显而易见。 对水处理其它程序的研究一直是这和其他文件的范围。几年来，研究者关注的是发展中国家间的合作，他们正在致力于水处理的替代过程，主要考虑可持续发展，社会承受能力和可行性等理念。在这个意义上，自然混凝絮凝剂这一广为传播，易于操作的资源即使是非专业人员也不难操作。有一些例子，如辣木[ 14 ]和仙人掌榕[ 15 ]。丹宁可能是一个新的混凝剂和絮凝剂。 一些开拓者已经研究了丹宁水处理能力。 ?zacar和sengil [ 16 ]：从瓦罗NIA获得的丹宁，从土耳其的autoctonous树的果壳中获得丹宁，并用于他们的–污水混凝絮凝过程。他们表明，丹宁有很好的效果，结合Al2（SO4）3可进一步提高污泥去除率。 詹和赵[ 17 ]试着用丹宁为主要成分的凝胶作为吸收剂除去水中的铝，丹宁凝胶改进了金属去除过程，一定意义上也可参照Nakano等人的[ 18 ]，Kim 和Nakano[ 19 ]。 ?zacar和sengil [ 20 ]加强以前的文章给出了关于三卤甲烷的形成和其他不良化合物特殊的数据，以及处理后的水质安全。他们始终使用丹宁与Al2（SO4）3的组合。 帕尔马等人将丹宁从辐射松的树皮为原位提取，用于重金属去除中聚合固体。树皮本
污水处理英文翻译解析 河流污水处理的相关论述 1 前言 随着工业化和城市化的发展，水环境污染、水资源紧缺日益严重，水污染控制、水环境保护已刻不容缓。我国现在新建城市或城区采用雨污分流制，但老城市或老城区大多仍然是雨污合流的排水体制。许多合流污水是直接排放到水体。而将旧合流制改为分流制，受现状条件限制大许多。老城区建成年代较长，地下管线基本成型，地面建筑拥挤，路面狭窄，旧合流制改分流制难度较大。合流污水的一大特点是旱季和雨季的水质、水量变化大，雨季污水 BOD 浓度低，不利于生化处理。国家提出 2010 的我国城市污水处理率要求达到 40%, 因此研究有效的合流污水处理方法对加快城市污水处理步伐具有重要的意义。本文针对合流污水处理的有关情况，谈一些个人看法。 2 污水处理工艺要求 我国目前不少城市，新城区与老城区并存，合流制与分流制并存。因此，新建或扩建的污水处理厂，在满足城市总体规划和排水规划需要的同时，还应能达到如下要求: 1. 具备接纳旧城区合流污水的能力，具有较强的适应冲击负荷的能力。污水处理厂污水来源包括两部分，一是新城区分流污水，二是老城区合流污水。与合流污水相比，分流污水水质、水量变化幅度小得多，对污水处理厂调节缓冲的要求小得多。对于合流污 水，降雨前期因雨水冲刷街区，合流污水较脏，但水量相对较小，降雨后期水量较大，但污水中有机物浓度相对较小。因此，降雨前期合流污水，可考虑与分流污水一起经预处理后进入污水处理构筑物。降雨后期合流污水，除一部
分与分流污水一起经污水预处理构筑物进入污水处理构筑物外，另一部分可考虑通过雨污溢流构筑物进入雨污溢流沉定池后排入附近水体。为了对进入污水处理构筑物的合流污水高峰流量、水质波动进行缓冲调节，污水处理构筑物前端可设缓冲调节池以均衡水质、储存水量。 2. 具有可靠的 BOD、 COD、 SS 去除功能及氮磷去除功能，保证最终出水水质稳定。通常情况下，城市污水中难降解有机物较少， BOD、 COD 去除比较容易实现，而氮磷去除则较复杂。我国现行的污水排放标准对污水处理厂出水氮磷指标有严格的要求，故城市污水处理都必须达到氮磷的有效去除。在现行城市污水脱氮除磷工艺中， A2/0 采用较为广泛。针对 A2/0 工艺存在的问题目前出现了许多改进工艺，每种工艺又都存在各自的特点和局限。由于合流污水引起的水质、水量波动较大，对污水厂各处理单元产生冲击，为了适应受纳水体的要求，为使 BOD、COD 等指标进一步降低，进一步去除污水中的细菌及氮、磷等植物性营养物质，在污水厂与受纳水体之间可设氧化塘。 3. 具有灵活多变的运行方式，可根据收集的污水量、进水水质以及季节变化调整运行方式。常规 A2/0 工艺，很难做到灵活方便地调整运行方式。但 A2/0工艺从构成原理上讲，是在曝气段前 加厌氧段和缺氧段。这一原理用于氧化沟技术，便可形成各种适应不同水质、水量、季节变化的运行方式。污水厂可根据实际情况设两个以上的氧化沟，每个沟设一定数量的水力推进器，池底均匀分布微孔爆气器。通过调整氧化沟污水进水管阀门、曝气器的开及关的区域、内回流比大小、污泥回流比大小及水力推进器运行个数，便可形成串联、并联等若干种运行方式。每种运行方式具有各自区域大小不同的厌氧段、缺氮段、曝气段。当旱季污水量小则采用串联运行方式，雨季污水量大，则采用并联运行方式。夏季温度高，硝化反应速度快，则采用具有较小曝气区域、较小硝化段的运行方式，相应反硝化区域
工业废水处理课程论文 题目：重金属废水处理方法综述 姓名： XXX 学号： XXXXX 学院：环境学院 专业：环境工程 班级： 1班 指导老师： XX 二零一二年五月十四日
重金属废水处理方法综述 摘要：本文介绍了几种典型的重金属废水处理方法，主要包括化学沉淀法、还原法、吸附法、膜分离法、混凝法、离子交换法、电化学法等，并对上述方法的机理、优缺点进行了综述。关键词：重金属废水处理方法机理优缺点 一引言 随着现代工业的高速发展，重金属工业废水的排放量日益增加，水质更加复杂，其中有些属于致癌、致畸或致突变的剧毒物质对人类危害极大。在环境污染方面所说的重金属主要指汞、铬、镉、铅、镍、铜等不具备自然净化能力，难被生物氧化分解且毒性极强的金属元素。重金属废水主要来源于电镀、矿山开采、机械加工、有色金属冶炼、废旧电池垃圾处理，以及农药、医药、油漆、颜料等生产过程排放的废水。目前，研究经济、高效的重金属工业废水的处理技术已成为环保工作的当务之急。水体重金属污染已经成为我国和世界上最严重的环境问题之一，对重金属废水的治理受到国内外科研工作者的高度重视。 二重金属废水处理方法 （一）我国重金属废水污染现状 近年来随着城市现代化水平和工业生产的发展，废水排放量逐年增加，我国水体重金属污染问题越来越严重，这主要是工业重金属废水的大量排放造成的，高达80.1%江河湖库底质受到污染，各类地表水饮用水体中重金属的超标现象严重。35.11%的城市河流的河段出现总汞含量超过地表水三类水体标准的现象，25%的河段总铅含量超过三类水体标准，18.46%的河段有总镉含量的超标样本出现。黄河、淮河、辽河等十大流域的水质中重金属含量超标断面的污染程度均为劣五类；黄浦江水系表层沉积物调查发现，九条支流中铜、锌、镉、铅污染较严重，干流汞含量明显增加，更为严重的是镉超背景值2倍，铅超1倍；苏州河中铅全部超标，镉为75%超标，汞为62.5%超标。进入江河等的污染物最终流入海洋，致使重金属污染的危害殃及博大的海洋，如果对此现象不加重视和控制，这种危害将越来越严重。 （二）重金属处理方法
1.文献综述 农村生活生活污水治理研究进展 摘要：农村生活污水是面源污染的主要来源，污染已对农村地区的水体、土地等自然环境产生严重影响，为确保农村水源安全和农民身体健康，农村污水治理刻不容缓。国民经济和社会发展第十一个五年规划纲要提出了建设社会主义新农村，国内掀起了新农村建设的热潮。具有战略高度的新农村建设已经将农村及村镇地区的给排水问题提上了日程。了解村镇基本情况，分析总结村镇污水特点，探讨村镇污水治理的适用工艺技术具有重要的意义。结合村镇生活污水水质水量特征分别介绍了氧化沟、接触氧化、化粪池技术、净化沼气池技术、人工湿地技术、人工快速渗滤技术等技术。 关键词：农村生活污水人工湿地组合技术 Farmers' concentration living sewage disposal are reviewed Abstract:Rural domestic sewage are the main sources of non-point source pollution, and pollution has water, land and other natural environment in rural areas of severe impact, in order to ensure the rural water supply security and farmers' health, so it is urgent to rural sewage treatment.The national economic and social development of the eleventh five-year plan outline is put forward in order to build a new socialist countryside, raised a hot wave of new rural construction in China. Strategic height of the new rural construction has water supply problem in rural and town area on the agenda.Understand the rural basic situation,analysis summary village sewage characteristics,discusses the application of the rural sewage treatment technology has important significance. In combination with characteristics of rural domestic sewage water respectively introduces the oxidation ditch technology,contact oxidation and septic tank. Keywords: Rural domestic sewage,Constructed wetland,Septic tank
氧化沟处理技术现状说明 美国华盛顿哥伦比亚特区水环境保护署办公室 一、总论 氧化沟是一种改良的活性污泥生物处理工艺，它是利用较长的固体停留时间（SRT）来去除可生物降解的有机物。氧化沟是典型的完全混合系统，但他们可以修改塞流条件。（注：由于塞流，必须通过空气扩散来保证完全的混合。该系统也将不再作为一个氧化沟）。典型的氧化沟处理系统包括一个或多个环形、椭圆形或马蹄形的渠道。因此，氧化沟被称为“跑道式”反应。通过安装水平或垂直的曝气机在氧化沟中曝气来提供氧气。 通常情况下在氧化沟之前设置预处理单元，如格栅、沉砂和沉淀等，但这也不是必须设置的。根据出水要求，可能需要在出水前设置三级过滤器，在最终排放之前有必要进行消毒。污泥从二沉池污泥回流到氧化沟再一次曝气和混合。典型的氧化沟工艺流程图如图1所示。 图1 典型氧化沟工艺流程图 表面曝气器，如转刷曝气器，转盘曝气器，导流管，或微小气泡扩散器可以保证污泥和水的充分混合。混合过程中氧气就进入到混合液中促进微生物新陈代谢，同时也保证了微生物与废水充分接触。通过曝气，增加了混合液中的溶解氧（DO）的浓度，但是随着混合液在氧化沟中流动，可供微生物吸收的溶解氧浓度逐渐降低,固体在氧化沟中保持着悬浮状态。可以通过硝化作用来设计停留时间，那样就会有很高的硝化程度，氧化沟出水通常是单独排到二沉池里，同时也可以在氧化沟之前增加一个厌氧池来提高除磷效果。 氧化沟也可以通过操作实现部分脱硝。常见的一种通过改进来强化脱氮效果的工艺，称为卢德扎克-艾丁格（MLE）过程。在这一过程中，如图2所示，通过
好氧区混合液的内回流来实现更高水平的反硝化。在好氧区，自养型细菌（硝化菌）将氨氮转化为亚硝酸盐和硝酸盐。在缺氧区，异养菌将硝态氮转化为氮气释放到大气中。一部分混合液从好氧区回流到缺氧区，给缺氧区提供了高浓度的硝态氮。 图2 改进的卢德扎克-艾丁格工艺示意图 为了去除停留在氧化沟中或在缺氧区和好氧区之间循环的营养物质，一些制造商已经找到了改良的办法。而不同制造商的方法不同，一般来说，整个过程包括两个独立的池子，第一个为缺氧池，第二个为好氧池。污水和回流活性污泥首先进入缺氧池，在缺氧条件下进行反应，随后混合液进入到好氧池进行第二反应。改良后，这一过程将会逆转，也就是说，第二反应将在缺氧条件下进行。 二、适用性 氧化沟工艺是一种活性污泥法（常规或延时曝气）处理废水的二次处理技术，适用于任何情况，任何废水都是合适的。通过选择合适的混合液最低温度和改变沟渠的大小选择适当的停留时间（SRT），可以达到预期的硝化效果。该技术在小型装置，小社区和偏远地区是非常适合的，因为它比传统的污水处理厂需要更多的土地。 氧化沟技术起源于荷兰，1954年，第一个具有完整规模的工厂安装在荷兰的福尔斯霍滕小镇。截止1998年，在美国就有9200多个城市配有氧化沟设施。为了脱氮设计和运行的氧化沟，通过硝化作用，可以使氨氮含量低于1 mg/L。 三、优缺点 3.1优点 氧化沟的主要优点是操作要求和运行维护成本低，有很高的去除能力。氧化沟的一些具体的优点包括：
附录Ⅰ： Wastewater Biological Treatment Processes The objective of wastewater treatment is to reduce the concentration of specific pollutants to the level at which the discharge of the effluent will not adversely affect the environment or pose a health threat. Moreover , reduction of these constituents need only be to some required level. For any given wastewater in a specific location , the degree and type of treatment are variables that require engineering decisions . often the degree of treatment depends on the assimilative capacity of the receiving water . DO sag curves can indicate how much BOD must be removed from wastewater so that the DO of receiving water is not depressed too far . The amount of BOD that must be removed is an effluent standard and dictates in large part the type of wastewater treatment required . To facilitate the discussion of wastewater , assume a “ typical wastewater ”and assume further that the effluent from this wastewater treatment must meet the following effluent standards : BOD≤15mg/L SS≤15mg/L P≤1mg/L Additional effluent standard could have been established , but for illustrative purposes we consider only these three . The treatment system selected to achieve these effluent standards includes 1. Primary treatment : physical processes that nonhomogenizable solids and homogenize the remaining effluent . 2. Secondary treatment : biological process that remove most of the biochemical demand for oxyen . 3. Tertiary treatment : physical , biological , and chemical processes to remove nutrients like phosphorus and inorganic pollutants , to deodorize and decolorize effluent water , and to carry out further oxidation .
毕业设计开题报告 一、本课题设计的目的和意义 随着我国经济的飞速发展，目前全国年排污量约为350亿立方米,但城市污水集中处理率仅为15％，全国超过80％的城市污水未经任何有效的收集处理就直接排放到附近的水体，使得原本具有泄洪和美化景观作用的河渠变成了天然污水渠。城市规模不断向周围扩展，小区服务功能越来越强，在众多城市的边缘地区以及旅游景区出现了许多新的小区，如宾馆、别墅、学校、休闲娱乐设施、医院等。小区污水的来源变得复杂化，污水的性质也更恶劣。这些小区往往远离城市污水处理厂，没有市政管网覆盖，给集中处理带来不便，小区污水大都就近排入地面水体，污染了周围环境，使地面水体水质恶化。因此，处理好小区生活污水，减少其对城市的环境污染具和解决水资源紧缺和高效利用有积极而重要的意义。 本课题经过查找相关文献资料，选择合理工艺处理小区污水，使达到达标排放或回用目的。 利用所学专业知识用于本次毕业设计——小区污水处理设计中，凭此来熟悉并掌握排水工程的设计内容、设计原理、方法和步骤，能根据原始设计资料正确地独立地选定设计方案，熟悉设计计算书和设计说明书的编写内容和编制方法。
二、设计依据、原则 （1）设计依据 ①《污水综合排放标准》(GB8978—1996)； ②《建筑给排水设计规范》(GBJl5—88)； ③《给水排水快速设计手册》； ④《城市污水处理厂污水污泥排放标准》(GJ3025-95） ⑤《生活杂用水水质标准》(CJ25.1 - 89) （2）指导原则 根据污（废）水的处理要求小区废水的自身特点，指导原则如下： （1）出水处理和处理程度。不同地区出水要求差异较大，因此需要因地制宜和实际需要，参照相关标准采取合理工艺达到处理要求。 （2）协调一致。小区污水处理设施要与小区建筑相协调，力求美观。 （3）简单实用，节省空间，考虑长远。尽量采用立体结构工艺，高程布置上充分利用地下空间，空间布置要紧凑,以节省用地。位于下风向，与小区保持一定距离，减少环境影响。根据小区人口增加情况，可考虑20年左右设计实用寿命。（4）处理程度高，污泥产量少，尽量采取节能工艺。保持合理污水处理符合和冲击符合，使工艺运行稳定高效。 （5）基础数据可靠 认真研究基础资料、基本数据，全面分析各项影响因素，充分掌握水质特点和地域特性，合理选择好设计参数，为工程设计提供可靠的依据。 （6）针对水质特点选择技术先进、运行稳定、投资和处理成本合理的处理工艺，积极慎重的采用经过实践证明行之有效的新技术、新工艺、新材料和新设备，使处理工艺先进，运行可靠，处理后水质稳定的达标排放。 （7）避免二次污染 尽量避免或减少对环境的负面影响，妥善处置处理渗滤液工程中产生的栅渣、污泥，臭气等，避免对环境的二次污染。
我国农村生活污水处理现状和对策 摘要：针对农村生活污水已经成为影响中国农村水环境质量主要因素之一的现状，从适合中国农村生活污水分散式处理的思维人手，介绍了我国现今主要的分散式生活污水处理技术的原理、特点、不足及其应用现状。 关键词：农村生活污水处理技术问题 1、农村生活污水处理的现状不容乐观 随着农村经济的快速发展，农村生活污水排放量增大，使农村地区环境状况日益恶化，农村环境质量明显下降，直接威胁着广大农民群众的生存环境与身体健康，制约了农村经济的健康发展，农村环境状况令人担忧。我国有96%的村庄没有排水渠道和污水处理系统，生产生活污水随意排放。89%的村庄将垃圾堆放在房前屋后、坑边路旁甚至水源地、泄洪道、村内外池塘，无人负责垃圾收集与处理。目前全国农村每年有超过 2500 万吨的生活污水直接排放，造成河流、水塘污染，影响村民居住环境，严重威胁农民的身体健康。农村污水处理的特征首先是处理率低，其次是间歇排放，排量少且分散，第三是氮磷浓度高及含有大量的营养盐、细菌、病毒等，这些都给农村污水的收集和处理带来了一定的难度。 2、农村生活污水处理常用工艺介绍 2.1 好氧生物处理工艺 适用于小量污水处理的好氧生物处理工艺主要有生物接触氧化、生物滤池、生物转盘、序批式反应器（SBR）等。我国农村生活污水处理应用较多的好氧生物处理工艺是生物接触氧化法。生物接触氧化法是在生物滤池的基础上，通过接触曝气形势改良而演变出的一种生物膜处理技术。生物接触氧化技术是介于活性污泥法和生物膜法之间的处理技术。在填料表面上培养微生物，形成生物膜，并采用与曝气池相同的方法向微生物供氧，污水流过时与填料上的生物膜接触，通过微生物的新陈代谢作用降解污水中的污染物从而达到净化的目的。生物接触氧化工艺占地面积小、处理负荷高、污泥产量少、抗冲击能力强、维护管理简便。生物接触氧化工艺对冲击负荷有较强的适应能力，在间歇运行条件下仍能保持良好的处理效果，对于水量不均匀的农村生活污水处理更具有实际意义。然而对于农村生活污水来说生物接触氧化工艺的投资和运行费用偏高，所以此工艺适合于我国南方及东部城市化速度快、比较富裕的农村推广应用。 2.2 人工湿地和稳定塘系统 2.2.1 人工湿地工艺
(文档含英文原文和中文翻译) 中英文资料对照外文翻译 Catalytic strategies for industrial water re-use Abstract The use of catalytic processes in pollution abatement and resource recovery is widespread and of significant economic importance [R.J. Farrauto, C.H. Bartholomew, Fundamentals of Industrial Catalytic Processes, Blackie Academic and Professional,1997.]. For water recovery and re-use chemo-catalysis is only just starting to make an impact although bio-catalysis is well established [J.N. Horan, BiologicalWastewater Treatment Systems; Theory and Operation, Chichester, Wiley,
1990.]. This paper will discuss some of the principles behind developing chemo-catalytic processes for water re-use. Within this context oxidative catalytic chemistry has many opportunities to underpin the development of successful processes and many emerging technologies based on this chemistry can be considered . Keywords: COD removal; Catalytic oxidation; Industrial water treatment 1.Introduction Industrial water re-use in Europe has not yet started on the large scale. However, with potential long term changes in European weather and the need for more water abstraction from boreholes and rivers, the availability of water at low prices will become increasingly rare. As water prices rise there will come a point when technologies that exist now (or are being developed) will make water recycle and re-use a viable commercial operation. As that future approaches, it is worth stating the most important fact about wastewater improvement–avoid it completely if at all possible! It is best to consider water not as a naturally available cheap solvent but rather, difficult to purify, easily contaminated material that if allowed into the environment will permeate all parts of the biosphere. A pollutant is just a material in the wrong place and therefore design your process to keep the material where it should be –contained and safe. Avoidance and then minimisation are the two first steps in looking at any pollutant removal problem. Of course avoidance may not be an option on an existing plant where any changes may have large consequences for plant items if major flowsheet revision were required. Also avoidance may mean simply transferring the issue from the aqueous phase to the gas phase. There are advantages and disadvantages to both water and gas pollutant abatement. However, it must be remembered that gas phase organic pollutant removal (VOC combustion etc.,) is much more advanced than the equivalent water COD removal and therefore worth consideration [1]. Because these aspects cannot be over-emphasised，a third step would be to visit the first two steps again. Clean-up is expensive, recycle and re-use even if you have a cost effective process is still more capital equipment that will lower your return on assets and make the process less financially attractive. At present the best technology for water recycle is membrane based. This is the only technology that will produce a sufficiently clean permeate for chemical process use. However, the technology cannot be used in isolation and in many (all) cases will require filtration upstream and a technique for handling the downstream retentate containing the pollutants. Thus, hybrid technologies are required that together can handle the all aspects of the water improvement process[6,7,8]. Hence the general rules for wastewater improvement are: 1. Avoid if possible, consider all possible ways to minimise.
带有支路流的固定膜反应器的强化脱氮除磷工艺 H. U. NAM, J. H. LEE, C. W. KIM M and T. J. PARK* M 环境工程系，釜山国立大学，釜山，609-735，韩国 于1999年3月1日首发，于1999年7月1日修订 摘要——在一个固定膜反应器内以支路流的操作方式来有效使用碳源内部来脱氮除磷的可能性正在被研究。有关证实在附有支流的固定膜反应器中，随着支流比例从0增加到0.4，城市污水中的氮磷是否能被有效去除的试验正在进行。被用在这个实验中的固定膜反应器是一种结合A 2 /O工艺和生物膜过程的反应器。支流被应用在这个实验中，部分出水直接被排入缺氧池中来有效的脱氮。根据出水流量的比例，支路流的比例在0,0.3和0.4中调节。在整个过程中，能观察到COD，NH+4-N,和T-P分别的去除效率超过87.2%，75.2%和52.8%。进一步说，依据入流速度，除磷的最佳运行条件预测是在支路流比例为0.4，且内外循环比都为0.5的时候。在支路流比例为0.4时，NH+4-N的去除率为88.0%，T-P的去除率为68.0%。由于支路流比例的不同，除磷效果也会大大不同。在支路流比例为0,0.3和0.4时，T-P的去除效率分别为52.8%，61.6%和68.0%。有人指出，带有支路流的固定膜反应器能实现完全脱氮，并且有助于提高磷的去除。2000 Elsevier 科学有限公司，版权所有。
关键词——合并的固定膜反应器，支路流，脱氮，磷的吸收，A2/O工艺，内循环，外循环，缺氧状态。 简介 从观察营养成分所产生的有机物质的数量和未处理的污水所产生的有机物的数量的对比，可以阐述受纳水体的氧源所排出的营养物质的潜在影响。韩国未经处理的污水所含的COD通常在200—250mg/L，根据是否磷酸盐洗涤剂在当地的禁令上磷的成分在4—6mg/L左右浮动，氮的含量在20—40mg/L之间（Choi， 来表示，如果1kg磷被藻1996）。假设藻类的组成能用化学式P C N H O 106 110 16 263 类完全同化并且在光合作用和无机元素的作用下被生成新的生物质，那将生成111kg生物质和138kg的COD。因此，每5mg/L的磷的排放会潜在的导致690mg/L 的COD的生成，或者相当于超过2倍的未经处理的污水中的有机物产生的COD 量。 据推测限制氮和磷的排量能控制富营养化因为相对硫、钾、钙、镁来说，生物质的生长所需氮磷的量相当大。近年来学术界认为在淡水环境中磷是最主要的限制营养物，而氮则是河口和海洋水域中的主要限制营养物（Sedlak，1989）。生物膜工艺有许多特点和优势（Park et al 1995,1996): (1)系统中使用的薄膜能有效的去除氮是由于所使用的菌类像硝化细菌之类有很缓慢的生长速率和很长的代谢时间；（2）由于薄膜上有更多生物物种的存在和活性污泥法的结合，能够实现广谱污染物的去除；（3）由于单元里有较大的生物量，每单元工艺的处理容量比活性污泥法要高出很多；（4）相较于活性污泥法，产生的剩余污泥量少。更多的污泥被存在于该膜上的高热带水品生物体所消耗，于是产生的剩余污泥量就变少了；（5）该工艺能稳定操作。该工艺能维持和适应液压波动和有机负荷，因为该工艺相对活性污泥法来说有大量的生物质和更长的食物链。另一方面，生物膜工艺也存在着一些缺点：（1）由于需要很多的支撑物和媒介，所以需要大量的初始资金；（2）打破厌氧薄膜层的微小颗粒非常活跃，会使出水的浊度变得很高。（Lee et al,1996; Su and Ouyang,1996) 本文的目标是开发一个新的带有支路流的固定膜反应器来去除污水中的营养