高悬浮物矿井水处理系统工艺改进研究

为了提高矿井水处理系统的处理能力,改善出水水质,降低运行费用,实现矿井水的资源化回用,对某矿高悬浮物矿井水处理工艺系统进行了改进研究。改进后的处理工艺采用"絮凝污泥回流强化助凝反应+高密度预沉淀+混凝反应+高效沉淀",部分出水采用石英砂滤罐进一步降低浊度后供给工人洗澡用水。首先通过对浊度为802 NTU的原水进行的混凝试验研究确定了2号PAC与PAM为最佳混凝剂和助凝剂,最佳投加量分别为140 mg/L、0.1 mg/L,出水浊度可降为2.3 NTU;在此基础上,为了进一步降低药剂投加量以降低水厂的运行费用,采用絮凝污泥回流强化助凝反应并完成高密度预沉淀后再进行混凝沉淀处理。结果表明:当絮凝污泥回流比为原水量的12%时,混凝反应时最佳投药量PAC、PAM分别为80 mg/L、0.1 mg/L,PAC投药量降低了43%,出水浊度可降为2.1 NTU。     

电镀废水处理站DTCR辅助氢氧化物沉淀工艺改造

某废水处理站改造前采用传统氢氧化物沉淀工艺处理高浓度含铬、氰镉电镀废水,运行不稳定,出水不能达标排放。工艺改造后增加了高分子重金属捕集沉淀剂DTCR辅助去除重金属,在含铬废水DTCR投加量为50 mg/L、含氰镉废水DTCR投加量为10 mg/L条件下,出水总铬、镉分别稳定在0.5 mg/L、0.2 mg/L以下,远低于《电镀污染物排放标准》(GB 21900—2008)限值。     

天津纪庄子再生水厂泥渣回流强化混凝沉淀工艺技术研究

通过对天津纪庄子再生水厂原水(城市二级出水)进行泥渣回流强化混凝试验研究,证明回流泥渣量在100～300mg/L时效果较好;当泥渣回流后,PAC投药量明显减少,只需5mg/L,基本能达到不加泥渣时投药量15mg/L的效果,节省了67%的投药量。通过正交试验确定混凝沉淀工艺的最佳混凝条件:快速搅拌45s,搅拌速率150r/min;慢速搅拌20min,搅拌速率50r/min。并且污泥浓度为10000～20000mg/L时的污泥回流才能得到比较好的处理效果。     

微砂增效结团絮凝技术处理低浊高藻水的中试研究

针对西安市汤峪水库夏季水质特点和处理要求,提出并采用微砂增效结团絮凝工艺对该原水处理进行中试研究.微砂增效结团絮凝技术是将微砂增效与结团絮凝有机组合的新型水处理工艺.试验结果表明,利用微砂增效结团絮凝技术处理汤峪水库低浊高藻水是切实可行的,系统具有运行稳定性高、出水水质好等特点,且处理效率明显高于采用回流污泥的增效澄清技术.微砂增效结团絮凝工艺能够有效降低出水浊度和CODMn;当微砂投量0.5 g/L时的过程控制参数为PAC投量15mg/L,PAM投量0.4 mg/L,机械搅拌转速8 r/min,上升流速达35 m/h时,藻类去除率可达80％,CODMn去除率达40％,浊度可控制在1.5 NTU以下.     

清潭污水处理厂一级A提标改造工程脱氮除磷特性分析

结合清潭污水处理厂一级A提标改造工程实例,通过全流程生产性测试和主要功能单元的模拟试验,对回流污泥内源反硝化强化环沟型改良A2/O工艺的脱氮除磷特性进行了分析。结果表明,回流污泥内源反硝化池HRT为3.2h时,内源反硝化NO-3—N去除量为9.6mg/L,污泥内源反硝化速率为0.68mgNO-3—N/(gVSS·h);在进水COD/TN为3.3的条件下,工艺脱氮能力高达35mg/L,回流污泥内源反硝化池、缺氧池和生物同化作用对工艺脱氮的贡献率分别为27.4%、44%和28.6%。通过将初沉池改造为回流污泥内源反硝化池,工艺脱氮能力提高37.8%;在进水PO3-4浓度均值为3.22mg/L时,好氧池出水PO3-4可达0.3mg/L以下,厌氧池厌氧释磷作用显著,PO3-4释放量高达8.3mg/L,污泥厌氧释磷速率为9.68mgPO3-4/(gVSS·h)。     

高浓度机械加工废水处理工程

采用混凝气浮—Fenton氧化—SBR—活性炭吸附工艺处理某公司机械加工废水,在进水CODCr、石油类和SS分别为50000～300000mg/L、1000～1500mg/L、1300～2000mg/L情况下,处理后的出水CODCr、石油类和SS分别可达150～300mg/L、5～8mg/L、35～60mg/L,极大降低了废水中的污染物质。     

物化-生化法处理汽车生产废水

针对汽车生产废水的特点,对含磷废水和高浓度有机废水分别采用石灰法和混凝沉淀-气浮法进行分质预处理.预处理出水与其它废水混合后形成的综合废水的设计处理能力为50 m3/h,COD 300～600 mg/L,PO3-(以P计)3～5 mg/L,经混凝沉淀-生化-过滤工艺处理后,COD≤100mg/L,PO43-(以P计)≤0.5 mg/L,可达标排放.     

CSBR-混凝沉淀组合工艺处理印染废水

印染废水色度大,有机物含量高,可生化性差,且水量和水质变化大,水质成分复杂,针对上述特点,采用了CSBR-混凝沉淀组合工艺处理印染废水,运行结果表明,在进水CODCr为1 200mg/L、BOD5为350 mg/L、SS为200 mg/L、色度为400倍、pH为11.5时,出水水质达到《纺织印染行业水污染物排放标准》(GB 42872-92)二级标准.该处理系统耐冲击负荷能力强,运行稳定,剩余污泥量少,基建和运行费用较低.     

污水处理厂升级改造中总磷控制工艺的研究

采用改良A2/O+化学除磷工艺进行污水处理厂改造,研究各运行参数对系统去除有机物和总磷(TP)的影响。结果表明,当HRT=8 h,污泥回流比为50%,硝化液回流比200%,填料的容积比为25%,投加PAC药剂为30 mg/L时,出水TP<0.5 mg/L,达到《城镇污水处理厂污染物排放标准》(GB 18918—2002)一级A排放标准。     

金沙江原水中铁锰去除研究

金沙江干流水质较好,但溪洛渡水电站河段铁、锰含量超标。在深入研究除铁、除锰工艺的基础上,提出加氯、高锰酸钾预氧化+曝气沉砂+絮凝沉淀+石英砂V形滤池过滤去除铁、锰的工艺,并将其应用于金沙江溪洛渡水电站施工期生活水厂中。结果表明:洪水期预氧化剂氯气投加量为0.5 mg/L、高锰酸钾投加量为0.5 mg/L的条件下,沉淀池出水铁含量为0.29 mg/L、锰含量为0.16 mg/L,滤后水铁含量为0.04 mg/L、锰含量为0.01 mg/L,出厂水水质综合合格率为100%。     

MBR工艺处理城镇污水处理厂污泥水中试研究

将平板膜组件与传统脱氮除磷工艺相结合,构建了膜生物反应器强化生物脱氮除磷中试系统,并用于处理城镇污水处理厂的污泥系统废水。结果表明,出水CODCr、BOD5、NH3—N、TN和TP的平均浓度分别为70.8 mg/L、8.7 mg/L、15.1 mg/L、29.7 mg/L和0.38 mg/L,达到或接近了《城镇污水处理厂污染物排放标准》(GB 18918—2002)的一级标准。     

Recalcitrant COD degradation by an integrated system of ozonation and membrane bioreactor.

In order to treat wastewater to a low residual COD-concentration such as 125 mg/L, classical biological treatment is not sufficient for many types of industry. This research focused on the integrated treatment of the wastewater of the paper industry, with a membrane bioreactor (MBR) and an oxidation step. The optimal configuration was examined. Screening tests with different types of oxidation showed that ozonation after biological treatment could reduce the COD with 40% with an ozone dose of 0.4-0.8g O3/g COD. BOD/COD ratio could be increased up to 0.19. Neither combination of ozone with UV and/or hydrogen peroxide nor the process H2O2/UV or (photo-)Fenton reagents gave any improvement in COD reduction or BOD increase, unless the doses were very high. Based on these results, an integrated system MBR-ozonation was designed, with recirculation of MBR effluent over ozonation. This test showed that reduction of COD up to 125 mg/L immediately behind the MBR required a lot of ozone. A technically feasible solution was to discharge the water after an extra ozonation step, which resulted in a high total ozone dosage. The alternative, the consecutive treatment activated sludge-ozonation-activated sludge, did not give a better COD-removal with the same ozone dose as the integrated concept. The economic evaluation proves that the integrated chemical and biological treatment is expensive for the paper industry if a low discharge limit of COD has to be complied with.     

Comparison between ozonation and the OSA process: analysis of excess sludge reduction and biomass activity in two different pilot plants

The excess biomass produced during biological treatment of municipal wastewater represents a major issue worldwide, as its disposal implies environmental, economic and social impacts. Therefore, there has been a growing interest in developing technologies to reduce sludge production. The main proposed strategies can be categorized according to the place inside the wastewater treatment plant (WWTP) where the reduction takes place. In particular, sludge minimization can be achieved in the wastewater line as well as in the sludge line. This paper presents the results of two pilot scale systems, to evaluate their feasibility for sludge reduction and to understand their effect on biomass activity: (1) a pilot plant with an ozone contactor in the return activated sludge (RAS) stream for the exposition of sludge to a low ozone dosage; and (2) an oxic-settling-anaerobic (OSA) process with high retention time in the anaerobic sludge holding tank have been studied. The results showed that both technologies enabled significant excess sludge reduction but produced a slight decrease of biomass respiratory activity.     

Occurrence of benzothiazoles in municipal wastewater and their fate in biological treatment.

A number of 2-substituted benzothiazoles that are known to be used as fungicides, corrosion inhibitors and vulcanization accelerators in industry have been analyzed in municipal wastewater and the effluents of activated sludge and membrane bioreactor (MBR) treatment over a three month period. All six analytes were regularly detected in the municipal wastewater by liquid chromatography-mass spectrometry and amount to a total concentration of 3.4 microg/L. Of these compounds benzothiazole-2-sulfonic acid (1,700 ng/L), benzothiazole (850 ng/L) and 2-hydroxybenzothiazole (500 ng/L) were most prominent. The source of the benzothiazole emission is yet unknown. Activated sludge treatment did not reduce total benzothiazole concentration significantly. Removals of the individual compounds ranged from 90% for 2-mercaptobenzothiazole and 70% for hydroxybenzothiazole to 40% for benzothiazole. The concentration of benzothiazole-2-sulfonic acid increased by 20%, whereas 2-methylthiobenzothiazole increased by 160% during activated sludge treatment, likely due to the methylation of mercaptobenzothiazole. Total benzothiazole removal in two parallely operated MBRs was significantly better (43%) than in the conventional activated sludge treatment. Namely benzothiazole and benzothiazole-2-sulfonic acid were more effectively removed. This first systematic study on the occurrence of benzothiazoles in municipal wastewater has shown that this is a relevant class of trace contaminants in municipal wastewater which is only incompletely removed in biological wastewater treatment. Emission from sewage treatment is dominated by the most polar benzothiazole-2-sulfonic acid. MBR treatment may reduce but cannot avoid this emission.     

Production of porous carbonaceous adsorbent from physical activation of sewage sludge: application to wastewater treatment.

With an objective of production of carbonaceous sorbent for industrial effluent treatment, physical activation by steam of biological sludge collected from the municipal wastewater treatment plant of Nantes (France) was studied and optimised using experimental design. Thus, this activation process consists of a carbonisation under N2 atmosphere at 600 degrees C for 1 h, followed by a thermal oxidation using steam (760 degrees C, 0.5 h, 2.5 L/Umin). The global mass yield of the process is equal to 38%. The thermal treatment allows a specific surface area of up to 225 m2/g to be reached, the porous structure being composed of both micropores and mesopores. The content of acidic surface groups is 0.71 mEq/g whereas that of basic surface groups is 0.55 mEq/g. The adsorption properties of the sorbent made from sludge are estimated with regard to various pollutants representative of industrial pollution of wastewaters and compared with those of commercial activated carbon. Whereas the adsorption capacities of organic micropollutants are quite low because of proportionality to the microporosity, the important mesoporosity of the sorbent leads to interesting properties for macromolecules removal from aqueous solutions, such as dyes (q(m) = 175-200 mg/g). Furthermore, the surface functional groups and Ca2+ ions within the materials allow high copper ion adsorption capacities of 140 mg/g to be obtained. Finally, a techno-economic approach shows that the sludge activation process seems to be economically competitive with regard to incineration.     

Nitrogen removal from the saline sludge liquor by electrochemical denitrification.

Sludge liquor from the sludge dewatering process has a high ammonia content. In the present study, a lab-scale electrochemical (EC) system with a pair of Ti electrode plates was used for treating the sludge centrate liquor of digested wastewater sludge with a NH4(+) - N content of around 500 mg/L. The sludge liquor had a high salinity due to seawater being used for toilet flushing in Hong Kong. The results show that the EC process is highly effective for denitrification of the saline sludge liquor. Complete nitrogen removal could be achieved within 1 hr or so. The rate of EC denitrification increased with the current intensity applied. The best current efficiency for nitrogen removal was obtained for a gap distance between the electrodes at 8 mm. Electro-chlorination was considered to be the major mechanism of EC denitrification. The formation of chlorination by-products (CBPs) appeared to be minimal with the total trihalomethanes (THM) detected at a level of 300 microg/L or lower. The power consumption for EC denitrification was around 23 kWh/kg N. Additional electro-flocculation with a pair of iron needle electrodes could enhance the flocculation and subsequent sedimentation of colloidal organics in the sludge liquor, increasing the organic removal from less than 30% to more than 70%. Therefore, the EC process including both electro-denitrification and electro-flocculation can be developed as the most cost-effective method for treatment of the saline sludge liquor.     

Aerobic biological treatment of thermophilically digested sludge

Aerobic biological treatment of digested sludge was studied in a continuously operated laboratory set-up. An aerated reactor was filled with thermophilically digested sludge from the Moscow wastewater treatment plant and inoculated with special activated sludge. It was then operated at the chemostat mode at different flow rates. Processes of nitrification and denitrification, as well as dephosphatation, occurred simultaneously during biological aerobic treatment of thermophilically digested sludge. Under optimal conditions, organic matter degradation was 9.6%, the concentrations of ammonium nitrogen and phosphate decreased by 89 and 83%, respectively, while COD decreased by 12%. Dewaterability of digested sludge improved significantly. The processes were found to depend on hydraulic retention time, oxygen regime, and temperature. The optimal conditions were as follows: hydraulic retention time 3-4 days, temperature 30-35 degrees C, dissolved oxygen levels 0.2-0.5 mg/L at continuous aeration or 0.7-1 mg/L at intermittent aeration. Based on these findings, we propose a new combined technology of wastewater sludge treatment. The technology combines two stages: anaerobic digestion followed by aerobic biological treatment of digested sludge. The proposed technology makes it possible to degrade the sludge with conversion of approximately 45% volatile suspended solids to biogas, to improve nitrogen and phosphorus removal in reject water from sludge treatment units, and to achieve removal of malodorous substances after 8-9 days of anaerobic-aerobic sludge treatment.     

多级高浓度活性污泥法脱氮除磷中试研究

多级高浓度活性污泥法在不征地、不增加处理构筑物的情况下,以提高活性污泥浓度为指导思想,对现有城市污水处理厂进行升级改造,达到脱氮除磷的目的。中试研究表明,在试验条件下,出水CODCr为33～43mg/L,去除率92%左右;NH3-N为3～5mg/L,去除率90%左右;TP为1～1.7mg/L,去除率72%左右。系统保证了良好的脱氮除磷效果。     

Advanced treatment by anaerobic process followed by aerobic membrane bioreactor for effluent reuse in paper mill industry.

The operation of an activated sludge process at a paper mill (AIPM) in Hedera, Israel, was often characterized by disturbances. As part of a research and development project, a study on new biological treatment was initiated. The study included the operation of three pilot units: a. anaerobic treatment by upflow anaerobic sludge blanket (UASB); b. aerobic treatment by two pilot units including activated sludge and membrane bioreactor (MBR), which have been operated in parallel for comparison reasons. The pilot plant working on anaerobic treatment performed COD reduction from 2,365 to 755 mg/L, expressed as average values. Based on the pilot study, a full scale anaerobic treatment system has been erected. During a period of 100 days, after achieving steady state, the MBR system provided steady operation performance, while the activated sludge produced effluent characterized by oscillatory qualities. The following results, based on average values, indicate much lower suspended solids concentrations in the MBR effluent, 2.5 mg/L, as compared to 25 mg/L in the activated sludge. The ability to develop and maintain a concentration of over 11,000 mg/L of mixed liquor volatile suspended solids in the MBR enabled an intensive bioprocess at relatively high cell residence time. This study demonstrates that the anaerobic process, followed by aerobic MBR can provide effluent of high quality which can be considered for economic reuse in the paper mill industry.