Occurrence and removal of pharmaceuticals and hormones through drinking water treatment

The occurrence of fifty-five pharmaceuticals, hormones and metabolites in raw waters used for drinking water production and their removal through a drinking water treatment were studied. Thirty-five out of fifty-five drugs were detected in the raw water at the facility intake with concentrations up to 1200 ng/L. The behavior of the compounds was studied at each step: prechlorination, coagulation, sand filtration, ozonation, granular activated carbon filtration and post-chlorination; showing that the complete treatment accounted for the complete removal of all the compounds detected in raw waters except for five of them. Phenytoin, atenolol and hydrochlorothiazide were the three pharmaceuticals most frequently found in finished waters at concentrations about 10 ng/L. Sotalol and carbamazepine epoxide were found in less than a half of the samples at lower concentrations, above 2 ng/L. However despite their persistence, the removals of these five pharmaceuticals were higher than 95%.     

Selenate removal in methanogenic and sulfate-reducing upflow anaerobic sludge bed reactors

This paper evaluates the use of upflow anaerobic sludge bed (UASB) bioreactors (30 degrees C, pH=7.0) to remove selenium oxyanions from contaminated waters (790 microg Se L(-1)) under methanogenic and sulfate-reducing conditions using lactate as electron donor. One UASB reactor received sulfate at different sulfate to selenate ratios, while another UASB was operated under methanogenic conditions for 132 days without sulfate in the influent. The selenate effluent concentrations in the sulfate-reducing and methanogenic reactor were 24 and 8 microg Se L(-1), corresponding to removal efficiencies of 97% and 99%, respectively. X-ray diffraction (XRD) analysis and sequential extractions showed that selenium was mainly retained as elemental selenium in the biomass. However, the total dissolved selenium effluent concentrations amounted to 73 and 80 microg Se L(-1), respectively, suggesting that selenate was partly converted to another selenium compound, most likely colloidally dispersed Se(0) nanoparticles. Possible intermediates of selenium reduction (selenite, dimethylselenide, dimethyldiselenide, H(2)Se) could not be detected. Sulfate reducers removed selenate at molar excess of sulfate to selenate (up to a factor of 2600) and elevated dissolved sulfide concentrations (up to 168 mg L(-1)), but selenium removal efficiencies were limited by the applied sulfate-loading rate. In the methanogenic bioreactor, selenate and dissolved selenium removal were independent of the sulfate load, but inhibited by sulfide (101 mg L(-1)). The selenium removal efficiency of the methanogenic UASB abruptly improved after 58 days of operation, suggesting that a specialized selenium-converting population developed in the reactor. This paper demonstrates that both sulfate-reducing and methanogenic UASB reactors can be applied to remove selenate from contaminated natural waters and anthropogenic waste streams, e.g. agricultural drainage waters, acid mine drainage and flue gas desulfurization bleeds.     

Pharmaceuticals and personal care products (PPCPs) in surface and treated waters of Louisiana,USA and Ontario,Canada

A newly developed analytical method was used to measure concentrations of nine pharmaceuticals and personal care products (PPCPs) in samples from two surface water bodies, a sewage treatment plant effluent and various stages of a drinking water treatment plant in Louisiana, USA, and from one surface water body, a drinking water treatment plant and a pilot plant in Ontario, Canada. The analytical method provides for simultaneous extraction and quantification of the following broad range of PPCPs and endocrine-disrupting chemicals: naproxen; ibuprofen; estrone; 17beta-estradiol; bisphenol A; clorophene; triclosan; fluoxetine; and clofibric acid. Naproxen was detected in Louisiana sewage treatment plant effluent at 81-106 ng/l and Louisiana and Ontario surface waters at 22-107 ng/l. Triclosan was detected in Louisiana sewage treatment plant effluent at 10-21 ng/l. Of the three surface waters sampled, clofibric acid was detected in Detroit River water at 103 ng/l, but not in Mississippi River or Lake Pontchartrain waters. None of the other target analytes were detected above their method detection limits. Based on results at various stages of treatment, conventional drinking-water treatment processes (coagulation, flocculation and sedimentation) plus continuous addition of powdered activated carbon at a dosage of 2 mg/l did not remove naproxen from Mississippi River waters. However, chlorination, ozonation and dual media filtration processes reduced the concentration of naproxen below detection in Mississippi River and Detroit River waters and reduced clofibric acid in Detroit River waters. Results of this study demonstrate that existing water treatment technologies can effectively remove certain PPCPs. In addition, our study demonstrates the importance of obtaining data on removal mechanisms and byproducts associated with PPCPs and other endocrine-disrupting chemicals in drinking water and sewage treatment processes.     

Advanced treatment of the reverse osmosis concentrate produced during reclamation of municipal wastewater

The work investigated the treatment of the concentrate produced from the reverse osmosis treatment of an MBR effluent. Two conventional chemical processes, coagulation and activated carbon adsorption, and three advanced oxidation processes (electrochemical treatment, photocatalysis and sonolysis) were applied. Coagulation with alum gave dissolved organic carbon (DOC) removals up to 42%, while FeCl(3) achieved higher removals (52%) at lower molar doses. Adsorption with granular activated carbon showed the highest DOC removals up to 91.3% for 5 g/L. The adsorption isotherm was linear with a non-adsorbable organic fraction of around 1.2 mg/L DOC. The three oxidation methods employed, electrolytic oxidation over a boron-doped diamond electrode, UVA/TiO2 photocatalysis and sonolysis at 80 kHz, showed similar behavior: during the first few minutes of treatment there was a moderate removal of DOC followed by further oxidation at a very slow rate. Electrolytic oxidation was capable of removing up to 36% at 17.8A after 30 min of treatment, sonolysis removed up to 34% at 135W after 60 min, while photocatalysis was capable of removing up to 50% at 60 min.     

Distribution of estrogens, 17beta-estradiol and estrone, in Canadian municipal wastewater treatment plants

The distribution of female hormones, 17beta-estradiol and estrone, was determined in effluents of 18 selected municipal treatment plants across Canada. Replicate 24-h composite samples were collected from the influent and final effluent of each treatment plant, and the removal efficiency compared to the operational characteristics of the plants. In conventional activated sludge and lagoon treatment systems, the mean concentrations of 17beta-estradiol and estrone in influent were 15.6 ng/l (range 2.4-26 ng/l) and 49 ng/l (19-78 ng/l). In final effluents, the mean concentrations of both 17beta-estradiol and estrone were reduced to 1.8 ng/l (0.2-14.7 ng/l) and 17 ng/l (1-96 ng/l), respectively. 17beta-estradiol was removed effectively, >75% and as high as 98%, in most of the conventional mechanical treatment systems with secondary treatment. The removal of estrone was much more complex with removal varying from 98% to situations where the concentrations in the effluent were elevated above that detected in the influent. The estrogenicity, measured using a transfected estrogen receptor in yeast (YES) assay, was also variable, ranging from high removal to elevations of estrogenicity in final effluent. Although the apparent removals were not statistically correlated with either hydraulic (HRT) or solid (SRT) retention times, plants or lagoons with high SRT were very effective at reducing the levels of hormones. Well-operated plants that achieved nitrification also tended to have higher removal of hormones than those that did not nitrify. Laboratory aerobic reactor experiments confirmed the rapid removal of 17beta-estradiol, estrone, and estrogenicity when exposed to sewage slurries.     

Occurrence and treatment of wastewater-derived organic nitrogen

Dissolved organic nitrogen (DON) derived from wastewater effluent can participate in reactions that lead to formation of nitrogenous chlorination by-products, membrane fouling, eutrophication, and nitrification issues, so management of DON is important for both wastewater reuse applications and nutrient-sensitive watersheds that receive discharges from treated wastewater. This study documents DON occurrence in full-scale water/wastewater (W/WW) treatment plant effluents and assesses the removal of wastewater-derived DON by several processes (biodegradation, coagulation, softening, and powdered activated carbon [PAC] adsorption) used for advanced treatment in wastewater reuse applications. After varying levels of wastewater treatment, the dominant aqueous nitrogenous species shifts from ammonia to nitrate after aerobic processes and nitrate to DON in tertiary treatment effluents. The fraction of DON in total dissolved nitrogen (TDN) accounts for at most 52% in tertiary treated effluents (median = 13%) and 54% in surface waters impacted by upstream wastewater discharges (median = 31%). The 5-day biodegradability/bioavailability of DON (39%) was higher, on average, than that of dissolved organic carbon (DOC, 26%); however, upon chlorination, the DON removal (3%) decreased significantly. Alum coagulation (with ≥8 mg/L alum per mg/L DOC) and lime softening (with pH 11.3-11.5) removed <25% of DON and DOC without selectivity. PAC adsorption preferentially removed more DOC than DON by 10% on average. The results provided herein hence shed light on approaches for reducing organic nitrogen content in treated wastewater.     

Tertiary treatment of municipal wastewater by cypress domes

The feasibility of using cypress domes as an alternative to physical-chemical methods for tertiary treatment of sewage effluent was demonstrated over a 5-year period. Surface water quality in domes receiving effluent was degraded (low dissolved oxygen, high nutrient levels) compared to control domes, and the degree of treatment within the dome surface waters was relatively small. However, water samples from shallow wells and ceramic soil moisture tubes indicated that the underlying organic soils and clay sands served as an effective barrier to the transport of biochemical oxygen demand, nitrogen, phosphorus, sulfate, fluoride, potassium, sodium, calcium, and magnesium to the shallow aquifer immediately below. High percentage removals were observed for all measured water quality parameters between the surface and groundwater stations. Standing water quality following the cessation of sewage pumping did not return to the same quality as found for the natural dome within 20 months.     

Metal loadings and removal at a municipal activated sludge plant

Influent total and dissolved concentrations of cadmium, chromium, copper, nickel and zinc to the Edmonton Gold Bar Wastewater Treatment Plant were measured at hourly intervals for several days. Metal concentrations were generally higher than in other large western Canadian cities and exhibited distinct diurnal variations. With the exceptions of nickel and zinc, the metals existed largely in the particulate phase. Samples collected from various points throughout the plant suggested that removal efficiencies for cadmium, chromium and copper were high and those for nickel and zinc were variable and generally low. Metal concentrations in the final effluent did not generally exceed the maximum levels allowed for Canadian drinking waters.     

混凝沉淀中影响除铝效率的因素

通过去除饮用水中铝的一系列生产试验,主要研究了混凝沉淀过程中浊度、水温、pH值等因素对沉淀水余铝的影响,提出除铝可以分为降低溶解铝和去除颗粒铝的两种途径。余浊和余铝在一定浓度范围内呈线性相关关系,此时除浊能同时有效去除颗粒铝。在不同温度下有不同的最佳pH值,调节pH值有利于降低溶解铝,增加铝的可去除性。在此基础上,对水厂生产运行提出了一些建议。     

Secondary effects of anion exchange on chloride, sulfate, and lead release: systems approach to corrosion control

Water treatment processes can cause secondary changes in water chemistry that alter finished water quality including chloride, sulfate, natural organic matter (NOM), and metal release. Hence, the goal of this research was to provide an improved understanding of the chloride-to-sulfate mass ratio (CSMR) with regards to chloride and sulfate variations at full-scale water treatment plants and corrosion potential under simulated premise plumbing conditions. Laboratory corrosion studies were conducted using Pb-Sn solder/Cu tubing galvanic cells exposed to model waters with low (approx. 5 mg/L Cl⁻ and 10 mg/L SO₄^2-) and high (approx. 50 mg/L Cl⁻ and 100 mg/L SO₄^2-) concentrations of chloride and sulfate at a constant CSMR of ∼0.5. The role of NOM during corrosion was also evaluated by changing the type of organic material. In addition, full-scale sampling was conducted to quantify the raw water variability of chloride, sulfate, and NOM concentrations and the changes to these parameters from magnetic ion exchange treatment. Test conditions with higher concentrations of chloride and sulfate released significantly more lead than the lower chloride and sulfate test waters. In addition, the source of NOM was a key factor in the amount of lead released with the model organic compounds yielding significantly less lead release than aquatic NOM.     

制革废水处理厂及下游综合污水厂升级改造探究

对某制革废水处理厂和下游综合污水处理厂的进出水水质和沿程工艺段进行采样分析,得出制革废水处理厂出水NH3-N和TN平均浓度分别为77. 32、160. 93 mg/L,综合污水处理厂出水COD平均浓度为106. 8 mg/L,其中大部分是难降解COD,出水TN平均浓度为89. 93 mg/L,出水COD和TN是影响污水处理厂出水达标排放的主要指标。在小试中投加500 mg/L葡萄糖(以COD浓度计)时脱氮效果明显增强,综合污水处理厂出水TN浓度可稳定在15 mg/L以下。利用臭氧、活性焦和四相催化氧化深度处理综合污水处理厂二级出水,发现臭氧对COD基本没有去除效果,活性焦和四相催化氧化都能使COD浓度降至50 mg/L以下,但四相催化氧化去除单位COD的成本约是活性焦的29%、再生活性焦的49%。     

低温条件下微孔曝气氧化沟中试装置的调试及启动

采用微孔曝气氧化沟中试装置处理实际污水处理厂沉砂池出水,研究了中试装置在低温条件下实现启动的可行性和可靠性。结果表明,中试装置抗冲击负荷能力较强,在低温条件下(13~18℃),控制好氧区DO浓度为0. 5~1. 0 mg/L,系统运行稳定;试验后期,中试装置出水指标除TP外其余均满足《城镇污水处理厂污染物排放标准》一级A标准要求。因此,在低温条件下中试装置可通过降低系统曝气量实现启动。分析了除磷效果不佳的原因,主要与排泥不规律、接种污泥除磷能力较差、回流污泥中含有硝态氮等有关。     

The effect of primary sedimentation on full-scale WWTP nutrient removal performance

Traditionally, the performance of full-scale wastewater treatment plants (WWTPs) is measured based on influent and/or effluent and waste sludge flows and concentrations. Full-scale WWTP data typically have a high variance which often contains (large) measurement errors. A good process engineering evaluation of the WWTP performance is therefore difficult. This also makes it usually difficult to evaluate effect of process changes in a plant or compare plants to each other. In this paper we used a case study of a full-scale nutrient removing WWTP. The plant normally uses presettled wastewater, as a means to increase the nutrient removal the plant was operated for a period by-passing raw wastewater (27% of the influent flow). The effect of raw wastewater addition has been evaluated by different approaches: (i) influent characteristics, (ii) design retrofit, (iii) effluent quality, (iv) removal efficiencies, (v) activated sludge characteristics, (vi) microbial activity tests and FISH analysis and, (vii) performance assessment based on mass balance evaluation. This paper demonstrates that mass balance evaluation approach helps the WWTP engineers to distinguish and quantify between different strategies, where others could not. In the studied case, by-passing raw wastewater (27% of the influent flow) directly to the biological reactor did not improve the effluent quality and the nutrient removal efficiency of the WWTP. The increase of the influent C/N and C/P ratios was associated to particulate compounds with low COD/VSS ratio and a high non-biodegradable COD fraction.     

SMSBR去除焦化废水中有机物及氮的特性

选用一体化膜—序批式生物反应器 (SubmergedMembraneSequencingBatchReac tor ,简称SMSBR)处理焦化废水 ,考察了能否通过膜分离的强化作用提高生物处理系统对焦化废水的处理效果 ,使出水COD达到新的排放标准 ( <10 0mg/L) ,并提高脱氮效率。研究结果表明 :在HRT为 32 .7h ,平均COD容积负荷为 0 .4 5kg/ (m3·d)的条件下 ,出水COD可以稳定在 10 0mg/L以下 (平均为 86.4mg/L) ;要使COD达到新的排放标准 ,进水COD容积负荷应低于 0 .67kg/ (m3·d) (该负荷下出水COD在 10 0mg/L上下波动 ,平均为 10 6.3mg/L) ;好氧段存在明显的反硝化现象 ,使COD的去除得到强化 ;在保证系统温度、碱度、溶解氧和不受进水COD负荷冲击的情况下 ,出水NH3-N可低于 1mg/L ,但泥龄太长所产生的微生物代谢产物抑制了硝化反应过程中的硝酸盐细菌 ,使好氧段出水NO2 -N/NOx-N平均为 91.1% ,因此系统获得极其稳定高效的短程硝化作用 ,有利于进一步脱氮 ;按“缺氧 1—好氧—缺氧 2”方式运行时 ,若“缺氧 2”的HRT>8.4 4h ,可实现 81.34 %的反硝化率 (外加碳源 :COD/N为 2 .1g/g) ,平均TN去除率为 87.2 % ,最高达 90 .2 %。     

Temporal dynamics of dissolved and particulate organic carbon in the northern Adriatic Sea in relation to the mucilage events

The accumulation of dissolved and particulate organic matter may play an important role in mucilage formation in the northern Adriatic. Distributions of dissolved and particulate organic carbon were therefore investigated during the period June 1999-July 2002, when massive mucilage events occurred: in the summer of 2000 and, to a greater extent, of 2002. The seasonal variations in dissolved organic carbon (DOC) concentrations were significant, doubling in summer (up to 150 micromol L(-1)) with respect to winter. The particulate organic carbon (POC) variations were also very large, with a less pronounced seasonal pattern compared to DOC, because the POC changes are much more dependent both on river discharges and on phytoplankton blooms. The comparison of the concentrations between the period before (March-May) and after the onset of mucilage events (June-August) showed that DOC, but particularly POC, were higher in the period before the event of 2002, more markedly in the surface waters of low salinity. The POC increased, reaching mean concentrations of up to 36 micromol L(-1) in March 2002 before the outbreak of the massive mucilage formation in June. This suggests that POC may have a more important role in the mucilage formation than DOC. The highest seasonal variations of organic matter concentrations took place in the upper layer of lower salinity, stressing the importance of stratification and pycnoclines for accumulation and aggregation of the organic matter in the northern Adriatic. The POC contribution to the total organic carbon was low in the oligotrophic waters (DOC/POC ratio >15) and increased with the phytoplankton biomass in the productive waters (DOC/POC ratio <10). Particulate organic carbon predominated over the dissolved inside the mucilage aggregate (DOC/POC ratio <1), probably because aggregation processes, in which colloidal organic carbon is involved, are important. The organic carbon within the aggregates reached a concentration of 13.6 mmol L(-1) which was about 100 times more than in the surrounding waters or in the waters when the mucilages were absent. This indicates that distributions of organic carbon in the northern Adriatic can be extremely patchy during mucilage events.     

Occurrence and removal of N-nitrosamines in wastewater treatment plants

The presence of nitrosamines in wastewater might pose a risk to water resources even in countries where chlorination or chloramination are hardly used for water disinfection. We studied the variation of concentrations and removal efficiencies of eight N-nitrosamines among 21 full-scale sewage treatment plants (STPs) in Switzerland and temporal variations at one of these plants. N-nitrosodimethylamine (NDMA) was the predominant compound in STP primary effluents with median concentrations in the range of 5-20 ng/L, but peak concentrations up to 1 μg/L. N-nitrosomorpholine (NMOR) was abundant in all plants at concentrations of 5-30 ng/L, other nitrosamines occurred at a lower number of plants at similar levels. From concentrations in urine samples and domestic wastewater we estimated that human excretion accounted for levels of <5 ng/L of NDMA and <1 ng/L of the other nitrosamines in municipal wastewater, additional domestic sources for <5 ng/L of NMOR. Levels above this domestic background are probably caused by industrial or commercial discharges, which results in highly variable concentrations in sewage. Aqueous removal efficiencies in activated sludge treatment were in general above 40% for NMOR and above 60% for the other nitrosamines, but could be lower if concentrations were below 8-15 ng/L in primary effluent. We hypothesize that substrate competition in the cometabolic degradation explains the occurrence of such threshold concentrations. An additional sand filtration step resulted in a further removal of nitrosamines from secondary effluents even at low concentrations. Concentrations released to surface waters were largely below 10 ng/L, suggesting a low impact on Swiss water resources and drinking water generation considering the generally high environmental dilution and possible degradation. However, local impacts in case a larger fraction of wastewater is present cannot be ruled out.     

Methylmercury input to the Mississippi River from a large metropolitan wastewater treatment plant

Methylmercury (MeHg) and total mercury (THg) inputs to the Mississippi River from a large metropolitan wastewater treatment plant were measured to characterize the relative contribution of the treatment plant to in-stream loads of these contaminants. Concentrations of MeHg and THg were determined in filtered and unfiltered whole water samples collected weekly from the treatment plant effluent stream and from the river upstream of the plant discharge. Unfiltered MeHg concentrations in the plant effluent ranged from 0.034 to 0.062 ng L(-1) and were always less than those in the river (range: 0.083-0.227 ng L(-1)). The MeHg loading to the river from the treatment plant ranged from 0.026 to 0.051 g d(-1) and averaged 0.037 g d(-1) over the 13-week sampling period. The in-stream MeHg load in the river upstream varied widely depending on hydrologic conditions, ranging from 0.91 to 18.8 g d(-1) and averaging 4.79 g d(-1). The treatment plant discharge represented 1.6%, on average, of the in-stream MeHg load, ranging from 0.2 to 3.5% depending on flow conditions in the river. MeHg in treatment plant effluent was primarily in the filtered phase (mean: 57%, <0.2 microm), but in the river the filtered/unfiltered ratio (F/UF) was typically less than 30% except during a major precipitation runoff event, when F/UF increased to 78%. The MeHg/THg ratio in unfiltered treatment plant effluent varied little (range: 1.6-1.9%), suggesting that THg concentration can serve as a relatively accurate proxy for MeHg concentration in this effluent stream. Supplemental sampling of the treatment plant influent stream showed that removals of MeHg and THg across the treatment process averaged 97% and 99%, respectively. These results show the treatment plant to be effective in removing MeHg and THg from wastewater and in minimizing its impact on Hg levels in the receiving water.     

The behaviour of polychlorinated biphenyls in the primary sedimentation process of sewage treatment: A pilot plant study

The behaviour of polychlorinated biphenyls (PCB) in the primary sedimentation stage of sewage treatment has been studied using a pilot scale primary sedimentation plant. The plant was operated at different hydraulic loadings, selected to cover the range expected during normal operation of a sewage treatment works. Concentrations of PCB in raw sewage were found to be in the low ng l^?1 range and in the high ng l^?1 range in primary sludges. A relationship between raw sewage PCB concentrations and variations in the raw sewage flow to the full-scale sewage treatment works was evident. Removal efficiencies of PCB were found to be highest at dry weather flow and lowest at three times dry weather flow, their removals being comparable to those of suspended solids. Mass balances of PCB and suspended solids in the treatment process have been calculated and the possible sources of error considered. Comparisons of the results have been made with those of previous studies. The implications of the presence of PCB in waste waters and sewage sludges for water re-use and sewage sludge disposal are discussed.     

Effects of discharge on silver loading and transport in the Quinnipiac River, Connecticut.

Silver concentrations were measured in water and sediment samples collected from the Quinnipiac River in Connecticut. This river was chosen for study because of its history of industrialization and high levels of Ag contamination. Sewage treatment plant (STP) effluent accounts for approximately 15% of the total river discharge and approximately 60% of the dissolved Ag in the water column during baseflow conditions. Erosion of contaminated riverbank sediment is the primary source of particulate Ag in the river. Both dissolved and particulate Ag fractions vary as a function of river discharge. Increased discharge due to rain events decreases the relative importance of STP effluent, and thus dilutes the dissolved Ag concentration in the water column. Conversely, increasing discharge results in higher particulate Ag concentrations from increased erosion. The results of this study clearly indicate that both point and non-point sources contribute significantly to Ag loading in this river system, with the level of river discharge determining the relative importance of each.