混凝过程中EfOM有机组分的变化及对消毒副产物生成势的影响

研究了混凝对污水处理厂二级出水溶解性有机物(EfOM)的去除效果及有机组分的变化以及对三卤甲烷生成势(THMFP)和卤乙酸生成势(HAAFP)的影响。结果表明,弱酸性条件下混凝对EfOM的去除效果略优于中性条件。络合反应更能去除THMs前驱物,而网扫絮凝对HAAs前驱物的去除效果更好。结合原水和混凝水的三维荧光光谱和傅里叶红外光谱可知,COOH、芳香族的有机物和溶解性微生物副产物有较高的反应活性,易和氯反应生成THMs,而多糖、脂肪族和腐殖酸类物质具有较高生成HAAs的潜能。

污水二级生化出水有机物(EfOM)性质表征及去除研究现状

污水二级生化出水有机物(EfOM)是污水中经初级和二级生化处理后剩余的难降解有机物,EfOM是影响二级出水排放的主要限制因素,也是污水再生及回用处理中的主要目标去除物质.本文对现有EfOM的表征方法-分子量分布、亲疏水性分离、荧光光谱等进行了分类归纳,进一步总结了现有处理方法对EfOM性质特点的影响.以臭氧为核心的氧化技术和膜滤技术发挥了深度处理效能,降低了运行成本.

二级出水中有机物深度处理工艺的研究进展

随着我国经济发展,城市污水和工业废水排放量不断增加。由于目前污水处理厂多采用生物法,二次出水中仍含有部分难以被生物降解的有机物,如果不经过处理直接排放,会对人体和生态环境造成威胁。污水二级出水有机物(EfOM)是污水经二级生化处理后剩余的有机物,主要来源于天然有机物、可溶性微生物产物和合成有机化合物。文中介绍了EfOM的主要组成并对其进行了量化和表征,综述了各种深度处理工艺(即混凝、高级氧化、吸附、膜分离)在去除EfOM方面的性能和优缺点,并通过组合工艺对污染物去除效果与单一工艺进行对比分析,为EfOM的有效去除提供理论依据。

城市污水二级生化出水有机物(EFOM)深度去除研究现状

污水二级生化出水有机物是污水中经初级和二级生化处理后剩余的难降解有机物质。二级生化出水有机物的去除方法种类繁多,就目前二级生化出水有机物的深度处理方法、研究现状、存在的问题等进行了分析和总结。结合二级生化出水特性进行污水深度处理工艺的优化组合,是实现污水回用、缓解水资源短缺的最佳途径。

污水厂尾水补水对受纳水体氮磷形态与DOM时空分布特征的影响

城镇污水厂尾水水量稳定、水质可控,是补给河湖水系生态基流的可靠水源.为保障污水厂尾水补水安全,以合肥市王建沟为研究对象,分别于枯水期、丰水期开展污水厂尾水回补河道氮、磷形态及溶解性有机质(dissolved organic matter,DOM)的时空分布特征研究,探明污水厂尾水对回补河流的影响.结果表明:①王建沟经尾水补水后水质明显改善,补水河段污染物浓度空间上沿程上升,时间上水质标识指数特征表现为丰水期>枯水期,总氮(total nitrogen,TN)为主要污染因子.②尾水回补河道中氮形态以溶解态为主,主要存在形式为溶解态无机氮(dissolved inorganic nitrogen,DIN,占60.9%),且以硝态氮(NO_(3)^(−)-N)为主.除溶解态有机氮(dissolved organic nitrogen,DON)和亚硝态氮(NO2−-N)以外,其余形态氮浓度均表现为丰水期>枯水期.③磷主要以溶解态无机磷(dissolved inorganic phosphorus,DIP,占80.3%)为主,各形态磷浓度均表现为丰水期>枯水期.④枯、丰水期尾水回补河道DOM均以类腐殖质为主,占68%以上,DOM具有较强自生源、低腐殖化特征;同时,较枯水期而言,丰水期DOM结构更为复杂,平均相对分子质量和含量升高.研究显示:污水厂尾水回补河流尽管会导致氮、磷等污染负荷的输入,但在丰富河流水动力、生态基流保障、河流生态恢复等方面具有积极的效应;同时建议丰水期强化入河城市面源污染管控.

慢滤-低压纳滤对二级出水中有机物和抗生素抗性基因的去除效能研究

抗生素抗性基因(Antibiotic Resistance Genes,ARGs)作为新型环境污染物,在污水处理厂二级出水中被频繁检出,成为人类健康和生态安全的潜在威胁。本文采用慢滤-低压纳滤(Nanofiltration,NF)组合工艺去除二级出水中ARGs和溶解性有机物(Dissolved Organic Carbon,DOC),探讨该工艺对ARGs和DOC的去除机制及效能。结果表明,生物膜慢滤-NF组合工艺对二级出水中ARGs和DOC的去除效果最好,对DOC的去除率为82.5%,质量浓度降为2.0 mg/L;对富里酸类有机物和腐殖酸类有机物的去除率分别达到87.2%、85.8%,对不同分子质量区间有机物的去除率均在90%以上,其中,对>100 kDa、50~100 kDa以及10~<50 kDa区间有机物的去除率均在95%以上,出水中几乎不含有这类物质;组合工艺对4种ARGs(tet A、tet W、sulⅠ、sulⅡ)的去除量为10^(4.83)~10^(5.67)copies/mL;生物膜慢滤对水中细胞态和游离态ARGs的去除效果优于慢滤,其对细胞态和游离态ARG的削减量分别为10^(1.06)~10^(3.52)copies/mL和10^(1.73)~10^(3.07)copies/mL;水中DOC与不同类型ARGs均具有显著正相关性;生物膜表面生长的变形菌门、放线菌门、假单胞菌属及蛭弧菌属等微生物可以加强对水中ARGs和DOC的去除。综上,慢滤-NF组合工艺可以有效去除二级出水中的ARGs和DOC,可以作为二级出水深度处理的有效方式。

氯化消毒对溶解性有机质光化学活性影响研究进展

氯化消毒工艺在水处理中应用广泛,改变了水中溶解性有机质(DOM)的结构组成和光化学活性,进而在排入地表水后显著影响受纳水体中共存有机污染物的光化学降解.本文聚焦DOM消毒后的环境光化学行为,系统地综述了氯化消毒工艺对不同水体DOM分子量、物质组成、官能团结构等特征的影响,分析了光生活性物质的量子产率和稳态浓度的改变趋势,阐述了消毒后DOM对共存有机污染物光化学降解的影响机制,以期为全面了解和评估消毒工艺的生态影响提供科学参考.

川西侏罗系气藏产出水生化处理影响因素及技术优化

川西侏罗系气藏产出水中含有泡排剂、破乳剂、缓蚀剂及阻垢剂等多种类型化学药剂,有机物含量高。研究表明,生化处理技术对有机物去除效果较好,能有效降低污水COD,但生化处理易受多种因素影响,COD去除效果不稳定,出水水质指标波动较大。影响生化处理效果的主要因素包括氯离子浓度、营养物质、填料结垢、温度、溶解氧、水力停留时间等。通过实验掌握了生化系统运行的相关工艺参数,建议生化处理运行指标为:进水氯离子浓度18000~22000mg/L、Ca^(2+)含量<100mg/L、溶解氧4~6mg/L、温度20~30℃、水力停留时间130~140h。通过优化生化系统进水水质指标及运行参数,使生化处理后出水COD较优化前平均去除率提高约40%,生化出水发泡力较优化前平均降低约80%,蒸发处理能力大幅提高,蒸馏量由优化前的120~150m^(3)/d提升至180~260m^(3)/d。

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.

Tracking the reactivity of ozonation towards effluent organic matters from WWTP using two-dimensional correlation spectra

The characteristics of effluent organic matter(EfOM) from a wastewater treatment plant(WWTP) during ozonation were investigated using excitation and emission matrix(EEM)spectra, Fourier transform infrared spectroscopy(FT-IR) and high-performance size exclusion chromatography(HPSEC) at different ozone dosages. The selectivity of ozonation towards different constituents and functional groups was analysed using two-dimensional correlation spectra(2D-COS) probed by FT-IR, synchronous fluorescence spectra and HPSEC.The results indicated that ozonation can destroy aromatic structures of EfOM and change its molecular weight distribution(MWD). According to 2D-COS analysis, microbial humiclike substances were preferentially removed, and then the protein-like fractions. Terrestrial humic-like components exhibited inactivity towards ozonation compared with the above two fractions. Protein-like substances with small molecular weight were preferentially reacted during ozonation based on 2D-COS probed by HPSEC. In addition, the selectivity of ozone towards different functional groups of EfOM exhibited the following sequence:phenolic and alcoholic C\O groups > aromatic structures containing C_C double bonds >aliphatic C\H. X-ray photoelectron spectroscopy(XPS) further elucidated the preferential reaction of aromatic structures in EfOM during ozonation.

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.

Degradation of dissolved organic matter in effluent of municipal wastewater plant by a combined tidal and subsurface flow constructed wetland

Dissolved organic matter(DOM)is an important constituent of wastewater treatment plant(WWTP)effluent.A novel combined tidal and subsurface flow constructed wetland(TF-SSFCW)of 90 L was constructed for a ten-month trial of advanced treatment of the WWTP effluent.Excitation emission matrix(EEM)fluorescence spectroscopy,parallel factor(PARAFAC)analysis and a two end-member mixing model were employed to characterize the composition and removal process of the effluent DOM(EfOM)from the WWTP.The results showed that the TF-SSF-CW performed an efficient EfOM removal with dissolved organic carbon(DOC)removal rate of 88%and dissolved organic nitrogen(DON)removal rate of 91%.Further analysis demonstrated that the EfOM consisted mainly of two protein moieties and two humic-like groups;protein moieties(76%)constituted the main content of EfOM in raw water and humic-like groups(57%)became the dominating contributor after treatment.The EfOM from the WWTP was mainly of aquatic bacterial origin and evolved to a higher proportion of terrigenous origin with higher humification in the TF-SSF-CW effluent.A common controlling treatment-related factor for determining the concentrations of the same kind of substances(protein groups or humic-like groups)was revealed to exist,and the ratio of removal rates between the same substances in treatment was calculated.Our study demonstrates that the TF-SSF-CW can be a novel and effective treatment method for the EfOM from WWTPs,and is helpful for understanding of the character of EfOM in wetland treatment.

Effects of ozonation and coagulation on effluent organic matter characteristics and ultrafiltration membrane fouling

Effluent organic matter （EfOM） is the major cause of fouling in the low pressure membranes process for wastewater reuse. Coagulation and oxidation of biological wastewater treatment effluent have been applied for the fouling control of microfiltration membranes. However, the change in EfOM structure by pre-treatments has not been clearly identified. The changes of EfOM characteristics induced by coagulation and ozonation were investigated through size exclusion chromatography, UV/Vis spectrophotometry, fluorescence spectrophotometry and titrimetric analysis to identify the mechanisms in the reduction of ultrafiltration （UF） membrane fouling. The results indicated that reduction of flux decline by coagulation was due to modified characteristics of dissolved organic carbon （DOC） content. Total concentration of DOC was not reduced by ozonation. However, the mass fraction of the molecules with molecular weight larger than 5 kDa, fluorescence intensity, aromaticity, highly condensed chromophores, average molecular weight and soluble microbial byproducts decreased greatly after ozonation. These results indicated that EfOM was partially oxidized by ozonation to low molecular weight, highly charged compounds with abundant electron- withdrawing functional groups, which are favourable for alleviating UF membrane flux decline.

Effects of duckweed(Spriodela polyrrhiza)remediation on the composition of dissolved organic matter in effluent of scale pig farms

The swine effluent studied was collected from scale pig farms,located in Yujiang County of Jiangxi Province,China,and duckweed（Spriodela polyrrhiza） was selected to dispose the effluent.The purpose of this study was to elucidate the effects of duckweed growth on the dissolved organic matter composition in swine effluent.Throughout the experiment period,the concentrations of organic matter were determined regularly,and the excitationemission matrix（3DEEM） spectroscopy was used to characterize the fluorescence component.Compared with no-duckweed treatments（controls）,the specific ultra-violet absorbance at 254 nm（SUVA254） was increased by a final average of 34.4%as the phytoremediation using duckweed,and the removal rate of DOC was increased by a final average of 28.0%.In swine effluent,four fluorescence components were identified,including two protein-like（tryptophan,tyrosine） and two humic-like（fulvic acids,humic acids） components.For all treatments,the concentrations of protein-like components decreased by a final average of 69.0%.As the growth of duckweed,the concentrations of humic-like components were increased by a final average of 123.5%than controls.Significant and positive correlations were observed between SUVA254 and humic-like components.Compared with the controls,the humification index（HIX） increased by a final average of 9.0%for duckweed treatments.Meanwhile,the duckweed growth leaded to a lower biological index（BIX） and a higher proportion of microbial-derived fulvic acids than controls.In conclusion,the duckweed remediation not only enhanced the removal rate of organic matter in swine effluent,but also increased the percent of humic substances.

焦化废水生物出水中可溶解性有机物的分子识别

焦化废水中可溶解性有机物成分复杂、难生化降解。为从分子层次揭示焦化废水生物出水中可溶解性有机化合物的组成,首先使用二氯甲烷作为萃取剂,通过液液萃取将河北迁安宏奥工贸焦化厂的焦化废水生物出水分离成有机相和萃余相;对有机相进行四组分分离,根据四组分极性的不同,对极性较弱的饱和分和芳香分采用气相色谱-质谱联用仪(GC/MS)分析,对极性较强的胶质和沥青质采用傅里叶变换离子回旋共振质谱结合电喷雾电离源(ESI FT-ICR MS)分析;对极性强的萃余相用固相萃取法得到SPE洗脱物,并进行ESI FT-ICR MS分析。结果表明:饱和分中共检测到120种化合物,焦化废水经生物处理后的难溶解有机物主要为一些分子质量较大的正构烷烃和链烷烃;芳香分中检测到34种化合物,主要检测到较高含量的醇类、酯类和酚类化合物,其中酚类主要是苯酚的烷基取代物;胶质、沥青质和SPE洗脱物分别检测到N_(x)、N_(1)O_(x)、N_(2)O_(x)、O_(x)和O_(x)S_(1)5类主要碱性有机物和非碱性有机物,胶质和沥青质中的化合物类型分布相似,且沥青质中的化合物更加丰富,SPE洗脱物的化合物类型分布与胶质和沥青质差别较大。根据碳数分布和DBE值,分别得到了主要化合物分子的结构,为焦化废水深度处理工艺的优化和改进提供了理论依据。

聚硅酸铁去除焦化废水生化尾水有机物的效能研究

采用共聚法制备聚硅酸铁(PSF)混凝剂,与助凝剂聚丙烯酰胺(PAM)搭配构成PSF+PAM混凝体系处理焦化废水生化尾水,并与PAC(聚合氯化铝)+PAM混凝体系进行有机物去除性能的对比分析。结果表明,混凝剂质量浓度为1500~3500 mg/L、PAM质量浓度为10 mg/L、初始pH=7.8的条件下,PSF+PAM混凝体系对有机物去除的性能更优;混凝剂质量浓度为3000 mg/L时,PSF+PAM体系对废水COD、色度、UV_(254)的去除率较PAC+PAM体系分别提高了8.53%、3.68%、11.17%。紫外-可见分光光谱分析结果表明,PSF+PAM体系对尾水中单环芳香族化合物、多环芳烃与含氮杂环化合物的去除效果优于PAC+PAM体系;三维荧光光谱表征结果表明,PSF+PAM体系对尾水中色氨酸等类芳香性蛋白质、类富里酸、类腐殖酸的去除效果优于PAC+PAM体系。PSF+PAM体系对焦化废水生化尾水有机物有较好的去除性能。

紫外光高级氧化法处理二级出水中难降解有机物的研究

紫外光高级氧化法是处理二级出水中难降解有机物的有效方法。在紫外光作用下,以过一硫酸钾(PMS)、过氧化氢(H2O2)和次氯酸钠(NaClO)为氧化剂,研究了氧化剂类型、浓度和紫外光强度对二级出水中2,4-二硝基苯酚(DNP)和亚硝基二甲胺(NDMA)去除效率的影响。结果表明,NaClO的降解效果最好,当NaClO浓度为1 mmol·L^(-1)、处理时间为60 min时,DNP和DNMA的去除率分别为25%和20%,这是由于在紫外光的照射下,NaClO分解产生HOCl·和OCl·自由基的量子产率高于PMS和H_(2)O_(2)所致;当NaClO初始浓度为2.5 mmol·L^(-1)、处理时间为60 min时,二级出水中DNP和DNMA的去除效率分别达到了50%和35%,DNP去除效率高是由于NaClO分解产生的自由基对芳香族化合物降解活性更高所致。当紫外光强度为6×10^(-11)E·s^(-1)时,DNP和DNMA的去除效率较好,再增加光强度,去除效率增加不明显。

煤气化废水二级生化处理出水的有机物特征研究

为了明确煤气化废水二级生化处理出水的水质特征,试验应用超滤对废水进行分子量分级,采用XAD-8树脂进行分离,并进行光谱分析。结果表明,在不同分子量的各组分中,疏水性物质占比大于亲水性物质,其中疏水性中性有机物(HoN)占比最高。三维荧光光谱分析发现,疏水性有机酸(HoA)和HoN腐殖化程度较高,疏水性有机碱(HoB)中芳香族化合物和富里酸类有机物比较多,而亲水性有机物(HI)中富里酸类有机物和溶解性微生物代谢产物较多。