污水生物生态处理工艺中的脱氮机理研究

通过水解池-美人蕉湿地、水解/接触氧化池-菖蒲湿地现场实验装置考察了生物-生态工艺深度净化分散生活污水的效果。结果表明,水解池-美人蕉湿地尽管湿地停留时间达到7 d，出水NH⁺₄-N仍难以达到一级A（GB18918-2002）标准；而增加接触氧化池后，湿地停留时间仅2 d，组合工艺出水水质远优于一级A出水要求。美人蕉湿地脱氮的主要途径是湿地微生物的硝化/反硝化，植物吸收约占28%。对经接触氧化处理，NH⁺₄-N、NO^-₃-N浓度均较高的进水，菖蒲湿地可在C/N小于2时高效脱氮。菖蒲湿地对TN的去除占组合工艺TN去除量的79%，其中植物吸收仅占湿地除氮总量的8%。湿地介质的厌氧氨氧化活性试验表明，菖蒲湿地介质表面的微生物在无有机碳源存在的条件下，可使培养液中的NH⁺₄-N与NO^-₃-N、NO^-₂-N短期内发生同步脱氮，厌氧氨氧化可能是菖蒲湿地在进水低碳源条件下脱氮的主要原因。     

低温条件下BAF+SPD组合工艺对滇池入湖河水的脱氮效果

为缓解湖泊富营养化问题，需进一步降低入湖河流氮的含量。针对滇池流域新运粮河的低C/N水质特征，研究了冬季低温条件下的微曝气生物滤池（BAF）及固相反硝化（SPD）组合异位脱氮工艺。结果表明，BAF+SPD组合工艺启动挂膜阶段，约3周后，NH₄⁺-N的去除率达80%以上，而反硝化细菌增殖相对缓慢，约5周后，NO₃^--N的去除率达80%以上；稳定运行的低温阶段，除降雨时间外，NH₄⁺-N平均去除率达80%，出水NH₄⁺-N浓度<1 mg/L；NO₃^--N平均去除率达到85%以上，出水NO₃^--N浓度<1 mg/L；TN平均去除率达80%以上，出水TN浓度<2 mg/L，主要水质指标达到国家地表水Ⅴ类标准。     

水平潜流人工湿地系统处理微污染原水的研究

采用水平潜流人工湿地系统处理微污染原水，同时考察了水力停留时间、温度、水力负荷以及植物的生长状况等对人工湿地系统处理效果的影响。结果表明，水平潜流人工湿地系统对微污染原水有较好的处理效果，COD、TP、TN、NH⁺₄-N、NO^-₃-N和NO^-₂-N的平均去除率分别为51.55%、49.90%、51.74%、 47.36%、52.67%和63.23%。按照国家地表水环境质量标准（GB3838-2002），经过湿地处理后，出水COD平均值达到Ⅰ类；出水TP平均值达到Ⅱ类；出水TN平均值基本接近Ⅳ类；出水NH⁺₄-N平均值达到Ⅱ类。另外，研究表明, 本系统在水力停留时间为3 d时,水力负荷为0.2 m/d处理效果最好，温度的变化与污染物的去除率呈正相关关系，植物生长旺盛程度直接影响着整个系统的处理效果。     

pH值控制MAP法脱氮进程的可行性研究

MAP沉淀法处理高NH₃-N废水，操作简便，处理效果好。本试验以NH₃-N浓度为1 000 mg/L的模拟废水为研究对象，研究结果表明，在Mg²⁺∶PO^3-₄∶NH⁺₄=1.2∶1.2∶1（摩尔比）、NaOH投加量为675 g/L的条件下NH₃-N去除率高达98%以上。试验选择出水pH作为控制反应进程的参数，并建立了出水pH与NH₃-N去除率之间的关系。通过调整NaOH投加量控制出水pH在7.5～8之间时，NH₃-N去除率最高，可达98%以上。X-衍射图谱及定量分析表明，沉淀物中MAP的纯度较高，具有一定的回收价值。     

焦化废水深度处理试验研究

采用BC法＋复合过滤技术工艺对焦化废水生化出水进行深度处理试验。结果表明，在SE混凝剂投药量为30 mg/L、BC池停留时间为1.5 h、复合过滤器水力负荷为2.4 m³/（m²·h）的条件下，当深度处理进水水质为COD＝196.1 mg/L、色度＝120倍、NH₃-N＝35.1 mg/L时，其去除率分别为74.7%、86.7%和69.7%，出水可达回用水要求。     

复合沸石滤床修复北方景观水体的实验研究

以天然矿物质沸石、细砂及煤渣取代传统滤料构建复合基质生态床，表面种植景观植物，采用下向流-上向流运行方式修复北方景观水体。分别进行静态实验及不同循环速率下的动态实验，考察对水体污染物去除过程。结果表明，2种运行方式下对水体NH⁺₄-N去除率都在85%以上，其中以1 h为循环周期的运行方式去除率达97%，较静态提高12.8%；TN去除率最高为84%；TP去除不稳定，过程缓慢。煤渣层对NH⁺₄-N的去除效果差，硝化作用不彻底与反硝化作用的加强使下层出水NH⁺₄-N 、NO^-₂-N及NO^-₃-N浓度均高于上层。提高循环速率有利于对氮的去除。     

底泥修复对城市污染河道水体污染修复的影响研究

为开发城市黑臭河道的有效治理方法，利用人工模拟河道就河道底泥对上覆水体的二次污染、底泥污染生物修复对其氮磷营养盐释放及河道水体污染生物修复的影响进行了研究，并对实验结果进行了工程现场应证。研究结果表明：河道污染底泥生物修复状况对上覆水体水质产生大的影响，在底泥不加修复时，底泥污染物释放使水体COD、TP、NH₃-N浓度分别达到30～35 mg/L、0.4～0.5 mg/L和3.0 mg/L，底泥修复后分别为15～20 mg/L、0.1 mg/L和2.5 mg/L；底泥G值（y）与底泥氮、磷污染物释放量（x）呈负相关关系，关系式分别为：y=0.5124x-0.1394（R₂=0.9222），y=0.17772x-0.4781（R₂=0.8701）；结合底泥的生物修复，采用曝气增氧投加生物制剂措施对水体进行生物修复时COD、NH₃-N和PO^3-₄的去除率分别提高13.6%、25.0%和15.7%；对古廖涌的现场治理工程表明，在未对河道底泥进行生物修复的情况下，经过氧化塘预处理河道水体增氧-水体原位强化生物修复等措施的治理，河道中、下游水体又逐渐恢复黑臭，在对河道底泥进行修复后，河道污染水体水质得到显著的改善和提高。     

一体化A/O移动床生物膜反应器中DO、TN分布及脱氮效果研究

采用一体化A/O移动床生物膜法工艺，以模拟生活污水研究了该工艺的除碳脱氮效果，并对一体化移动床生物膜反应器的好氧区和缺氧区各纵向断面的COD、DO、NH₃-N、TN、NO^-₃-N和NO^-₂-N进行了检测，通过对缺氧区各断面的DO和TN浓度分布情况，分析了脱氮的产生过程。试验结果表明: 在水力停留时间HRT＝12 h，好氧区DO保持5 mg/L左右，COD进水浓度处于250～400 mg/L时，COD的去除率均在90%以上，且出水COD均在40 mg/L以下；TN进水浓度为20～50 mg/L时，NH₃-N去除率高于90%，其出水浓度可达到5 mg/L以下，脱氮效率也较高，TN去除率可达到65%～85%。COD和NH₃-N的浓度分布状况表明该一体化A/O移动床生物膜反应器的流态趋于全混式。     

臭氧-BAF组合工艺对石化行业废水深度处理的中试研究

采用臭氧-曝气生物滤池（BAF）组合工艺对中石化九江分公司二级生化出水进行深度处理中试实验。探讨了臭氧投加量、进水水质冲击负荷等因素对该组合工艺出水COD、NH₄⁺-N的影响。中试结果表明，在该水质条件下，臭氧最佳投加量为20~25 mg/L；组合工艺处理后出水COD低于40 mg/L，NH₄⁺-N低于5 mg/L，达到中水回用设计标准；该组合工艺能够经受一定冲击负荷。     

漂浮植物塘协同处理农村分散生活污水研究

通过实验考察了漂浮植物塘对经模拟化粪池简易处理的农村分散生活污水的深度净化效果，结果表明：水葫芦、大薸、聚草塘对上述污水均具有良好的净化效果，水葫芦塘对TP的去除效果最好，大薸塘对TN和NH⁺₄-N的去除效果最好。当水力停留时间为20 d时，3种漂浮植物塘的出水污染物含量可低于GB/T 18921-2002观赏性景观环境用水河道类标准。在南方农村宅沟园河内种植漂浮植物是构建农村实用生活污水收集处理系统、控制农村生活污水对河道污染的一种有效措施。     

Plasma vitellogenin in male teleost fish from 43 rivers worldwide is correlated with upstream human population size

It has been previously demonstrated that vitellogenin (VTG) - a precursor egg yolk protein - is produced in male fish exposed to estrogenic compounds in wastewater treatment plant (WWTP) effluent. However, little attention has been given to examine whether any patterns of male VTG production exists across fish species on a global scale. We hypothesized that a composite measure of human population size over river discharge would best explain variations of protein levels in male fish. We compiled VTG data in 13 fish species from 43 rivers receiving municipal WWTP effluent on 3 continents. We found that human population size explained 28% of the variation in male VTG concentrations, whereas population/flow rate failed to significantly correlate with VTG. We suggest this result may be explained by the low solubility of estrogenic compounds, resulting in localized contamination near WWTP outfalls, rather than dilution by river water.     

Polycyclic aromatic hydrocarbons in wastewater, WWTPs effluents and in the recipient waters of Beijing, China

In this study, surface water samples from the Wenyu River and the North Canal, effluent from major wastewater treatment plants (WWTPs) in Beijing, and wastewater from open sewers that discharge directly into the river system were collected and analyzed for 16 priority USEPA polycyclic aromatic hydrocarbons (PAHs). Concentrations of these 16 PAHs ranged from 193 to 1790 ng/L in river surface waters, 245 to 404 ng/L in WWTP effluents, and 431 to 2860 ng/L in the wastewater from the small sewers. The WWTP effluent was the main contributor of dissolved PAHs to the river, while wastewater from the small sewers contributed both dissolved and suspended particulate matter-associated PAH to the river as indicated by the high dissolved organic carbon and suspended particulate matter contents in the wastewater. Although the flow from each open sewer was small, a PAH discharge as high as 44 kg/year could occur into the river from these types of sewers. This amount was equivalent to about 22 % of the PAH loads discharged into the North Canal downstream from Beijing, whereas the remainder was mainly released by the major WWTPs in Beijing.     

Acidic pharmaceuticals in domestic wastewater and receiving water from hyper-urbanization city of China (Shanghai): environmental release and ecological risk

The occurrence, behavior, and release of five acidic pharmaceuticals, including ibuprofen (IBP), naproxen (NPX), ketoprofen (KEP), diclofenac (DFC), and clofibric acid (CA), have been investigated along the different units in a tertiary-level domestic wastewater treatment plant (WWTP) in hyper-urbanization city of China (Shanghai). IBP was the most abundant chemicals among the measured in raw wastewater. The loads of the acidic pharmaceuticals in the WWTP influent ranged from 7.5 to 414 mg/day/1,000 inh, which were lower than those reported in the developed countries suggesting a less per capita consumption of pharmaceuticals in Shanghai. IBP obtained by highest removal (87 %); NPX and KEP were also significantly removed (69–76 %). However, DFC and CA were only moderately removed by 37–53 %, respectively. Biodegradation seemed to play a key role in the elimination of the studied pharmaceuticals except for DFC and CA. An annual release of acidic pharmaceuticals was estimated at 1,499 and 61.7 kg/year through wastewater and sludge, respectively, from Shanghai. Highest pharmaceuticals concentrations were detected in the effluent discharge point of the WWTP, indicating that WWTP effluent is the main source of the acidic pharmaceuticals to its receiving river. Preliminary results indicated that only DFC in river had a high risk to aquatic organisms. Nevertheless, the joint toxicity effects of these chemicals are needed to further investigate.     

Wastewater reuse in Mediterranean semi-arid areas: The impact of discharges of tertiary treated sewage on the load of polar micro pollutants in the Llobregat river (NE Spain)

The presence of sewage-borne micro contaminants in environmental waters is directly related to the discharge of treated effluents from wastewater treatment plants (WWTP) and the flow rate of the receiving river waters. Mediterranean rivers, in particular, are characterized by important fluctuations in the flow rates and heavy pollution pressures resulting from extensive urban, industrial and agricultural activities. This translates into contamination levels in these rivers often higher than those in other larger European basins. The present work provides an overview of the occurrence of five groups of organic contaminants (131 compounds) namely pharmaceuticals, illicit drugs, polar pesticides, estrogens, alkylphenols and related ethoxylates in WWTP tertiary treatment effluents. Data gathered during a period of water reuse carried out in the lower stretch of the Llobregat river (NE Spain), in the surroundings of the town of Barcelona as a consequence of the severe drought that took place along the years 2007-2008 are presented as illustrative example. In general, measured concentrations of the target compounds were in the low to mid ng L⁻¹ range. The total concentration of each compound class downstream to the discharge point was similar or slightly higher than that found upstream. Regarding the loads calculated for each compound, the relative contribution from the river upstream and the tertiary effluent were highly compound depending with no apparent trend. However, estimation of the overall bulk loads for each compound class determined in the Llobregat river showed the following rank order: pharmaceuticals > alkylphenols > pesticides > illicit drugs ? estrogens.     

Occurrence and sources of antibiotics and their metabolites in river water, WWTPs, and swine wastewater in Jiulongjiang River basin, south China

In this study, the occurrence and sources of five cataloged antibiotics and metabolites were studied in Jiulongjiang River basin, south China. Nineteen antibiotics and 13 metabolites were detected in water samples from 16 river sampling sites, wastewater from 5 swine-raising facilities, and effluent from 5 wastewater treatment plants (WWTPs). The results showed that 12 antibiotics and 6 metabolites were detected in river water samples. Sulfonamides (SAs) and their metabolites were detected at high concentrations (8.59–158.94 ng/L). Tetracyclines (TCs) and their metabolites were frequently detected in swine wastewater, and the maximum concentration was up to the level in milligram per liter. Macrolides (MLs) and β-lactams (β-Ls) were found in all WWTP effluent samples and some river samples, while they were never found in any of the swine wastewater samples. SAs and quinolones (QNs) were detected in all samples. Hierarchical cluster analysis of 16 surface water samples was applied to achieve the spatial distribution characteristics of antibiotics in the Jiulongjiang River. As a result, two categories were obviously obtained. Principal component analysis and redundancy analysis showed that TCs and SAs as well as their metabolites were the major antibiotics in Jiulongjiang River, and they mainly originated from swine wastewater, while the QNs, MLs, and β-Ls in the Jiulongjiang River came from WWTP effluent.     

Perfluorooctanoic acid and perfluorooctane sulfonate in the sediment of the Roter Main river, Bayreuth, Germany

Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) are widely distributed in aquatic ecosystems. Their sources are known but few studies about their accumulation potential in river sediments exist. The aim of this study is to assess the concentrations of PFOA and PFOS in sediments in relation to their levels in river water receiving effluent from a waste water treatment plant (WWTP). PFOS accumulates by a factor of about 40 relative to river water, PFOA only up to threefold. In contrast to previous suggestions, in this case the enrichment on sediment is not correlated to the total organic carbon contents.     

Impact of wastewater treatment plants on receiving surface waters and a tentative risk evaluation: the case of estrogens and beta blockers

Five estrogenic hormones (unconjugated?+?conjugated fractions) and 10 beta blockers were analyzed in three wastewater treatment plant (WWTP) effluents and receiving river waters in the area of Lyon, France. In the different samples, only two estrogens were quantified: estrone and estriol. Some beta blockers, such as atenolol, acebutolol, and sotalol, were almost always quantified, but others, e.g., betaxolol, nadolol, and oxprenolol were rarely quantified. Concentrations measured in river waters were in the nanogram per liter range for estrogens and between 0.3 and 210 ng/L for beta blockers depending on the substance and the distance from the WWTP outfall. The impact of the WWTP on the receiving rivers was studied and showed a clear increase in concentrations near the WWTP outfall. For estrogens, the persistence in surface waters was not evaluated given the low concentrations levels (around 1 ng/L). For beta blockers, concentrations measured downstream of the WWTP outfall were up to 16 times higher than those measured upstream. Also, the persistence of metoprolol, nadolol, and propranolol was noted even 2 km downstream of the WWTP outfall. The comparison of beta blocker fingerprints in the samples collected in effluent and in the river also showed the impact of WWTP outfall on surface waters. Finally, a tentative environmental risk evaluation was performed on 15 sites by calculating the ratio of receiving water concentrations to predicted non-effect concentrations (PNEC). For estrogens, a total PNEC of 5 ng/L was considered and these substances were not linked to any potential environmental risk (only one site showed an environmental risk ratio above 1). Unfortunately, few PNECs are available and risk evaluation was only possible for 4 of the 10 beta blockers studied: acebutolol, atenolol, metoprolol, and propranolol. Only propranolol presented a ratio near or above 1, showing a possible environmental risk for 4 receiving waters out of 15.     

Winter accumulation of acidic pharmaceuticals in a Swedish river

Purpose  

In this study, seasonal variations in the concentration profile of four analgesics and one lipid regulator were monitored on their way from a wastewater treatment plant (WWTP) effluent, along a river, and into a lake.     

Perfluorooctanoic acid and perfluorooctane sulfonate released from a waste water treatment plant in Bavaria, Germany

Purpose

Perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), and precursors and derivatives thereof have been employed as surfactants and anti-adhesives. PFOA and PFOS are environmentally persistent and the discharge of municipal waste waters is one of the principal routes of these compounds into the aquatic environment. In a previous study, the concentrations of PFOA and PFOS in grab samples collected from the waste water treatment plant (WWTP) of Bayreuth, a city of 72,000 inhabitants in Bavaria, Germany, during two periods showed considerable variability. For a better estimate of average mass flows, the surfactants were monitored (five samplings) from 16 March to 18 May 2007. In a second campaign, river water receiving the WWTP effluent was sampled twice a day for five consecutive days.

Methods

Quantitative analysis was done by stable-isotope dilution, pre-cleaning, and pre-concentration by solid-phase extraction, and liquid chromatography followed by electrospray ionization/tandem mass spectrometry.

Results

The mass flows of PFOA and PFOS through the WWTP were determined. PFOA is fully discharged into the river, while about half of PFOS is retained in the sewage sludge. The average daily mass load of the river Roter Main by the WWTP of Bayreuth is about 1.2?±?0.5 g PFOA and 5?±?2 g PFOS, with variations of up to 140% within one day.

Conclusion

Overall, the total annual release to the rivers of Germany may be in the range of several hundred kilograms of PFOA and several tons of PFOS.     

The occurrence of illicit and therapeutic pharmaceuticals in wastewater effluent and surface waters in Nebraska

The occurrence and estimated concentration of twenty illicit and therapeutic pharmaceuticals and metabolites in surface waters influenced by wastewater treatment plant (WWTP) discharge and in wastewater effluents in Nebraska were determined using Polar Organic Chemical Integrative Samplers (POCIS). Samplers were installed in rivers upstream and downstream of treated WWTP discharge at four sites and in a discharge canal at a fifth location. Based on differences in estimated concentrations determined from pharmaceuticals recovered from POCIS, WWTP effluent was found to be a significant source of pharmaceutical loading to the receiving waters. Effluents from WWTPs with trickling filters or trickling filters in parallel with activated sludge resulted in the highest observed in-stream pharmaceutical concentrations. Azithromycin, caffeine, 1,7-dimethylzanthine, carbamazepine, cotinine, DEET, diphenhydramine, and sulfamethazine were detected at all locations. Methamphetamine, an illicit pharmaceutical, was detected at all but one of the sampling locations, representing only the second report of methamphetamine detected in WWTP effluent and in streams impacted by WWTP effluent.