Effects of effluent organic matters on endocrine disrupting chemical removal by ultrafiltration and ozonation in synthetic secondary effluent

Endocrine disrupting chemicals(EDCs) in the secondary effluent discharged from wastewater treatment plants are of great concern when water reuse is intended. Ozonation and ultrafiltration(UF) are powerful technologies reported to eliminate EDCs. Due to the importance of effluent organic matters(EfOMs) in secondary effluent, the effects of three kinds of EfOM on the treatment of five EDCs using ozonation and UF were investigated. The three kinds of EfOM studied were humic acid sodium salt(NaAH), bovine serum albumin(BSA)and sodium alginate(NaAg); and the five EDCs were estrone, 17β-estradiol, estriol, 17α-ethynyl estradiol and bisphenol A. The results showed that EfOM accelerated the decay rate of ozone and inhibited the degradation efficiency of EDCs by ozonation in the order NaAH BSA NaAg.The ultraviolet absorbance at 280 nm(UVA_(280)) has potential for use as a surrogate indicator to assess EDC removal via ozonation without conducting difficult EDC analyses. When the decline in UVA_(280) exceeded 18%, the five EDCs had been completely removed. The UF behavior of NaAH,BSA and NaAg was found to follow the cake filtration law. The fouling potential of EfOM followed the order NaAg NaAH BSA; while EfOM on the membrane surface enhanced EDC removal in the order NaAH BSA NaAg. The mean retention rate of the membrane was increased by 24%, 10% and 8%, respectively. The properties of EDCs and EfOM cakes both influenced the EDC removal rates due to adsorption, size exclusion and charge attraction.     

Molecular characterization of effluent organic matter in secondary effluent and reclaimed water: Comparison to natural organic matter in source water

Municipal wastewater reclamation is becoming of increasing importance in the world to solve the problem of water scarcity. A better understanding of the molecular composition of effluent organic matter(Ef OM) in the treated effluents of municipal wastewater treatment plants(WWTPs) is crucial for ensuring the safety of water reuse. In this study, the molecular composition of Ef OM in the secondary effluent of a WWTP in Beijing and the reclaimed water further treated with a coagulation–sedimentation–ozonation process were characterized using a non-target Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR MS) method and compared to that of natural organic matter(NOM) in the local source water from a reservoir. It was found that the molecular composition of Ef OM in the secondary effluent and reclaimed water was dominated by CHOS formulas, while NOM in the source water was dominated by CHO formulas. The CHO formulas of the three samples had similar origins. Anthropogenic surfactants were responsible for the CHOS formulas in Ef OM of the secondary effluent and were not well removed by the coagulation-sedimentation-ozonation treatment process adopted.     

Genotoxicity removal of reclaimed water during ozonation

Genotoxicity in wastewater and reclaimed water now is gaining increased attention because of genotoxins' potential damage to the ecosystem and human health. The effect of ozonation on genotoxicity in reclaimed water was investigated. It was found that ozonation decreased the genotoxicy dramatically in three tertiary treatment plants. In the further batch ozonation experiment in laboratory,secondary effluent sample used exhibited the genotoxicity of(41.1 ± 4.1) μg 4NQO/L. Ozonation with a dose of 10 mg O3/L completely removed the genotoxicity in secondary effluent. However,after ozonation, the dissolved organic carbonvalue of the sample didn't change much but the specific ultraviolet absorbance(SUVA) value dropped sharply. With the help of Fourier transform infrared spectroscopy, ozonation was found to change chemical aliphatic carbon and C–O of the dissolved arganic matter, which might be the reason of the significant decreases of SUVA and genotoxicity.     

Removal and desorption of chromium in synthetic effluent by a mixed culture in a bioreactor with a magnetic field

Two chromium removal experiments were performed in bioreactors with and without a magnetic field under the same conditions.The release of the chromium present in the biomass was tested in two experiments one with the initial pH of the medium and one with pH 4.0.The objective was to remove Cr(Ⅵ) and total Cr from the effluent,this was carried out by placing biological treatments of synthetic effluent contaminated with 100 mg/L of Cr(Ⅵ) in a bioreactor with neodymium magnets that applied a magnetic field(intensity85.4 mT) to the mixed culture.The removal of Cr(Ⅵ) was approximately 100.0% for the bioreactor with a magnetic field and 93,3% for the bioreactor without a magnetic field for9 hr of recirculation of the synthetic effluent by the bioreactor.The removal of total Cr was61.6% and 48.4%,with and without a magnetic field,respectively;for 24 hr.The desorption of Cr(VI) in the synthetic effluent was 0.05 mg/L,which is below the limit established by Brazilian legislation(0.1 mg/L) for the discharge of effluent containing Cr(Ⅵ) into bodies of water.The results obtained for the removal of chromium in synthetic effluent suggested that there was no significant influence on the viable cell count of the mixed culture.The desorption of Cr(Ⅵ) in synthetic effluent after bioadsorption of chromium by the mixed culture in the process of removal of chromium in bioreactors with and without a magnetic field was not significant in either of the experiments with different initial pHs.     

Effect of different molecular weight organic components on the increase of microbial growth potential of secondary effluent by ozonation

Ozonation has been widely applied in advanced wastewater treatment. In this study, the effect of ozonation on assimilable organic carbon （AOC） levels in secondary effluents was investigated, and AOC variation of different molecular weight （MW） organic components was analyzed. Although the removal efflciencies were 47%-76% and 94%-100% for UV2s4 and color at ozone dosage of 10 mg/L, dissolved organic carbon （DOC） in secondary effluents was hardly removed by ozonation. The AOC levels increased by 70%-780% at an ozone dosage range of 1-10 mg/L. AOC increased significantly in the instantaneous ozone demand phase, and the increase in AOC was correlated to the decrease in UV254 during ozonation. The results of MW distribution showed that, ozonation led to the transformation of larger molecules into smaller ones, but the increase in low MW （〈1 kDa） fraction did not contribute much to AOC production. The change of high MW （〉100 kDa and 10-100 kDa） fractions itself during ozonation was the main reason for the increase of AOC levels. Furthermore, the oxidation of organic matters with high MWs （〉 100 kDa and 10-100 kDa） resulted in more AOC production than those with low MWs （1-10 kDa and 〈1 kDa）. The results indicated that removing large molecules in secondary effluents could limit the increase of AOC during ozonation.     

Toxicity-based assessment of the treatment performance of wastewater treatment and reclamation processes

The reclamation and reuse of wastewater is one of the possible ways to relieve the serious fresh water resource crisis in China. Efficient reclamation treatment technologies ensure the safe reuse of reclaimed water. In order to screen out and evaluate technologies appropriate for reclamation treatment, a great deal of efforts have been brought to bear. In the present study, a toxicity-based method including a Photobacterium phosphoreum test for acute toxicity and SOS/umu test for genotoxicity, accompanied by the traditional physicochemical parameters DOC (dissolved organic carbon) and UV₂₅₄ (absorbance at 254 nm), was used to measure the treatment performance of different reclamation processes, including the anaerobic-anoxic-oxic biological process (A²O) and subsequent physical/chemical reclamation processes (ultrafiltration, ozonation, chlorination). It was found that for the secondary effluent after the A²O process, both the toxicity and physicochemical indices had greatly decreased compared with those of the influent. However, chemical reclamation processes such as ozonation and chlorination could possibly raise toxicity levels again. Fortunately, the toxicity elevation could be avoided by optimizing the ozone dosage and using activated carbon after ozonation. It was noted that by increasing the ozone dosage to 10 mg/L and employing activated carbon with more than 10 min hydraulic retention time, toxicity elevation was controlled. Furthermore, it was shown that pre-ozonation before activated carbon and chlorination played an important role in removing organic compounds and reducing the toxicity formation potential. The toxicity test could serve as a valuable tool to evaluate the performance of reclamation processes.     

Impact of Fenton and ozone on oxidation of wastewater containing nitroaromatic compounds

Fenton and ozone treatment was investigated at laboratory scale for the degradation of aqueous solutions of nitrobenzene (NB).Effects of reactants concentration (O3,H2O2,and Fe(II)),temperature,and pH on NB degradation were monitored.Reaction kinetic of these processes was also assessed.A rapid reaction took place for Fenton process at higher initial concentration of H2O2,higher temperatures,and more acidic conditions(pH 3).Similarly, ozonation reaction exhibited rapid rates for higher ozone dose,higher temperatures,and more basic conditions(pH 11).Complete NB degradation in 65 min Was achieved using Fenton process.The conditions of complete elimination of 100 mg/L of initial NB concentration,were 250 mg/L of H2O2 concentration,pH 3,and 10 mg/L of Fe(Ⅱ) concentration.Under these conditions,55% organic carbon elimination Was achieved.Total organic carbon mineralization Was attained in 240 min reaction time by Fenton process with 900 mg/L of H2O2 concentration,and 30 mg/L of Fe(II) concentration.Fenton reaction showed a pseudo-first order kinetic;the reaction rate constant Was ranged from 0.0226 to 0.0658 min-1.Complete NB degradation wag also achieyed for an ozone dose of the order of 2.5 g/L.The ozonation Was studied at different ozone doses.different initial pH(7-11)and at difierent temperatures(15-35℃).NB ozonation kinetic Was represented by a bi-molecular kinetic model which was reduced to pseudo-first order kinetic.The pseudo-first order reaction rate constant was determined to increase at 20℃ from 0.004 to 0.020 min-1 as the used ozone increased from 0.4 to 1.9g/L.     

Adsorption and biodegradation of three selected endocrine disrupting chemicals in river-based artificial groundwater recharge with reclaimed municipal wastewater

Endocrine disrupting chemical(EDC) pollution in river-based artificial groundwater recharge using reclaimed municipal wastewater poses a potential threat to groundwater-based drinking water supplies in Beijing, China. Lab-scale leaching column experiments simulating recharge were conducted to study the adsorption, biodegradation, and transport characteristics of three selected EDCs: 17β-estradiol(E2), 17α-ethinylestradiol(EE2) and bisphenol A(BPA). The three recharge columns were operated under the conditions of continual sterilization recharge(CSR), continual recharge(CR), and wetting and drying alternative recharge(WDAR). The results showed that the attenuation effect of the EDCs was in the order of WDAR CR CSR system and E2 EE2 BPA, which followed first-order kinetics. The EDC attenuation rate constants were 0.0783, 0.0505, and 0.0479 m-1 for E2, EE2 and BPA in the CR system, respectively. The removal rates of E2, EE2, and BPA in the CR system were 98%, 96% and 92%, which mainly depended on biodegradation and were affected by water temperature.In the CR system, the concentrations of BPA, EE2, and E2 in soil were 4, 6 and 10 times higher than in the WDAR system, respectively. According to the DGGE fingerprints, the bacterial community in the bottom layer was more diverse than in the upper layer, which was related to the EDC concentrations in the water-soil system. The dominant group was found to be proteobacteria, including Betaproteobacteria and Alphaproteobacteria, suggesting that these microbes might play an important role in EDC degradation.     

A novel approach to treat combined domestic wastewater and excess sludge in MBR

Domestic wastewater was treated by combined anaerobic biofilm-aerobic membrane bioreactor(MBR) process, and part biomass in MBR was withdrawn, to treat with ozone, then the ozonated sludge was returned to anaerobic inlet. In aerobic MBR, MLSS and DO were controlled at 3000—3500 mg/L and 0.8 mg/L respectively. Comparing the experimental results of two stages, it was noticed that ozonation did not affect the removal efficiency for organics but had a significant influence on the removals of NHs-N and TN. During the ozonation period of two months, no excess sludge was wasted, and a zero sludge yield was obtained.     

Ozonation of refractory chemicals in leachate with hydrogen peroxide

Nearly 97% of organic chemicals in Hong Kong leachate could be effectively removed by the UASB( upflow anaerobic sludge blanket) process followed by the fenton coagulation. The COD of leachate was lowered from an average of 12900 mg/L to 1440 mg/L after the UASB treatment, and was further lowered to 394 mg/L after the fenton coagulation. The remaining refractory residues could be further removed by ozonation with the addition of H2Oz. The ozonation for the supernatant of the fenton coagulation was most effective at pH 7-8, with the addition of 300 mg/L of H202, and 30 min of reaction. The final effluent contained only 85 mg/L of COD and 10 mg/L of BOD5. On the other hand, direct ozonation of UASB effluent lowered the COD to 905 mg/L and BOD5 to 103 mg/L. Ozonation improved the biodegradability of the organic residues, and also converted oart of oruanic-N in the leachate into NH3-N and NO3^- -N.     

催化臭氧氧化与NaClO处理钛白粉废水中试对比

以山东某钛白粉厂二级压滤出水为研究对象,通过自主设计的中试设备考察了催化臭氧氧化工艺与NaClO工艺对钛白粉废水处理情况,确定催化臭氧氧化的最佳工艺实验条件为:在室温条件下,催化臭氧氧化反应时间为60 min,臭氧投加浓度为125 mg/L。对原有NaClO工艺进行优化,优化后的最佳工艺为:NaClO投加量为1.2%,反应时间为30 min。当平均进水ρ（COD）与ρ（NH₃-N）分别为109.7,12.8 mg/L,则催化臭氧工艺平均出水ρ（COD）与ρ（NH₃-N）分别为43.5,3.8 mg/L,平均去除率分别为60%和70.4%,NaClO工艺平均出水ρ（COD）与ρ（NH₃-N）分别为49.8,4.7 mg/L,平均去除率分别为54.5%和63.1%。在30 d内,催化臭氧氧化出水达标率为100%,NaClO出水达标率为26.7%,催化臭氧氧化处理费用为1.12元/t,NaClO处理费用为12元/t,催化臭氧氧化工艺相较于NaClO氧化工艺更适用于处理钛白粉废水。     

氯咪巴唑在臭氧降解过程中的影响因素及其降解产物

唑类抗真菌剂广泛应用于药物和个人护理品(pharmaceutical and personal care products,PPCPs)中,常规污水处理工艺难以将其有效去除. 大量唑类抗真菌剂排入受纳环境后会对生态系统造成一系列负面影响. 为了解唑类抗真菌剂的臭氧氧化降解过程和机理,以氯咪巴唑(climbazole,CZ)为例,通过设置不同条件的对比试验,系统研究CZ在臭氧氧化过程中的影响因素及其去除规律,同时采用超高效液相色谱-飞行时间质谱联用仪UPLC-Q/TOF对其降解产物进行鉴定. 影响因素试验结果表明:①CZ起始浓度由1.0 mg/L增至4.0 mg/L时,臭氧氧化20 min下CZ的降解率从99.1%降至69.3%;②反应体系起始pH由5.0升至9.0时,CZ臭氧降解半衰期由1.38 min延长至7.18 min;③臭氧流速由0.1 L/min增至0.4 L/min时,臭氧氧化20 min时CZ的降解率从66.5%提至99.4%,但臭氧流速超过0.3 L/min以后,CZ降解率的增幅较小;④自然水体及其高浓度共存组分(碳酸氢根和腐殖酸)均会明显抑制CZ的臭氧氧化反应速率,CZ降解半衰期大多数超过6 min (空白对照组为1.99 min). 因此,在臭氧氧化降解新兴有机污染物或对臭氧氧化工艺进行优化时,应充分考虑起始污染负荷、pH、臭氧流速、水体水质状况等对处理效果的影响. 产物鉴定结果表明:臭氧氧化反应可将CZ碎裂重组形成两个主要降解产物——TP269和TP297,二者的产率分别为11.45%和8.90%. 研究显示,起始污染负荷、pH、臭氧流速、水体水质状况均会明显影响CZ的臭氧降解效果;两个CZ臭氧降解产物的产率虽不高,但其毒性有待进一步研究.      

生物活性炭内吸附与生物降解协同去除有机污染物

本研究建立了一个确定BAC内2种机理去除有机物分配比例的试验方法.该方法以BAC进出水中溶解性有机碳（DOC）与可生物降解有机碳（BDOC）浓度变化作为评价参数,并利用此方法确定了臭氧投加量对2种去除机理的影响.臭氧化可以使BDOC浓度增加,臭氧投量为2～8mg/L时,BDOC增加0.12～0.54mg/L;BAC过滤使出水BDOC浓度降低为0.23～0.31mg/L.随着臭氧投量增加（2～8mg/L）,在BAC内生物降解作用去除有机物比例从46%增加到89%.     

臭氧-生物活性炭组合工艺中最佳臭氧投加剂量的确定

在水处理过程中投加臭氧,可提高饮用水的可生物降解性.臭氧氧化后继的生物过滤,可以减少水中可生物降解有机物数量,提高饮用水的生物稳定性.试验表明,臭氧投加量2～8mg/L可使AOC-P17,AOC-NOX和BDOC分别增加20.9%～85.5%,42.1%～158.2%和21.4%～84.4%.臭氧投加量为3mg/L时,AOC和BDOC增加得最多,即3mg/L的臭氧投量为最佳投加剂量.生物活性炭滤柱(BAC)出水AOC浓度(乙酸碳)均低于50μg/L,在35.9～46.6μg/L之间,属于生物稳定性水质.     

臭氧氧化深度处理二级处理出水的研究

以某城市污水处理厂二级处理出水为原水,研究了臭氧氧化深度处理对水中残留有机物以及病原微生物的降解和去除效果.结果表明,臭氧投加量达到6mg/L时,DOC、UV254、色度的去除率分别为15.49%、36.36%、73.61%,环境激素类痕量有机物邻苯二甲酸二丁酯(DBP)和邻苯二甲酸二(2-乙基己基)酯(DEHP)的去除率分别为37.29%和14.6%,三维荧光光谱荧光峰的各区域有机物质平均去除率在80%以上,DBP出水浓度为2.64mg/L,DEHP出水浓度为1.4mg/L,满足《城市污水再生利用地下水回灌水质》(GB/T 19772-2005)的标准.臭氧投加量达到10mg/L时,出水中指示性微生物粪大肠菌群仍接近103CFU/L,5mg/L有效氯消毒后出水粪大肠菌群仍接近10CFU/L,6mg/L臭氧与5mg/L有效氯组合消毒出水的粪大肠菌群下降至3CFU/L,满足《城市污水再生利用景观环境用水水质》(GB/T 18921-2002)的标准.三卤甲烷(THMs)的生成量随着有效氯投加量的增加而增加,臭氧与氯组合消毒过程与氯单独消毒过程相比,THMs生成量减少了78.08%.     

微絮凝砂滤-臭氧催化氧化强化石化生化出水COD去除

为强化石化生化出水COD的去除,采用微絮凝砂滤-臭氧催化氧化工艺处理石化生化出水,比较了臭氧催化氧化反应器不同氧化方式和不同回流比组合方式下COD的去除,开展了臭氧催化氧化深度处理单元小试、中试和生产性规模研究,确立了以双级臭氧催化氧化Ⅰ级自回流工艺（回流比100%）为双级臭氧催化氧化推荐的优化工艺。生化出水ρ（COD）为70~120 mg/L时,微絮凝砂滤出水ρ（COD）达到65~113 mg/L,Ⅱ级氧化出水COD平均去除率达到35.0%~42.6%,出水满足GB 31571-2015《石油化学工业污染物排放标准》排放限值要求。生产性试验条件下,优化工艺装置去除单位COD消耗臭氧量平均为1.04 g/g,比对照组现阶段生产工艺（仅Ⅰ级臭氧曝气）降低了21.2%。     

催化臭氧化法处理汽车厂综合废水的实验研究

根据臭氧化反应基本原理 ,选用Fe2 + 、Cu2 + 、H2 O2 、Fe2 + +H2 O2 等作催化剂 ,对臭氧在不同催化剂催化作用下降解汽车厂综合废水中有机物和氰化物的速率、最终去除率和臭氧利用效率进行了实验研究。实验结果表明 ,O3+H2 O2 +Fe2 + 工艺可高效去除废水中的有机物和氰化物 ,最终出水水质满足排放标准     

臭氧-MBR工艺深度处理印染废水中试研究

采用臭氧-膜式生物反应器(MBR)工艺对某工业园印染废水二级生化处理出水进行了深度处理,达到企业回用水要求。结果表明,在进水COD低于100 mg/L、色度为40倍的条件下,当臭氧投加量为15～20 mg/L、MBR的水力停留时间为4～6 h、气水比为15∶1时,出水COD<40 mg/L、色度为2倍,出水水质可满足企业对回用水的水质要求。     

水中天然有机物的臭氧强化光催化降解研究

研究了饮用水源中大分子天然有机物（NOM）的臭氧强化光催化降解,考察了臭氧投加量、反应时间和HCO3^-浓度对NOM降解速率的影响;分析了臭氧强化光催化过程中NOM相对分子质量的变化,并比较不同相对分子质量大小NOM的降解速率.研究结果表明,臭氧强化光催化比单独臭氧氧化、光催化能更有效地降解NOM,同时增加臭氧投加量和反应时间才能有效提高臭氧强化光催化对TOC的去除率,而单独增加臭氧投加量可显著提高生物可降解性;HCO3^-显著降低光催化的降解效果,臭氧强化光催化能有效地减弱HCO3^-的不利影响;臭氧强化光催化过程中大分子NOM分解为小分子,SUVA值迅速下降,且相对分子质量越大矿化速度越快.