物化＋生化法处理工业废水的试验研究初探

摘要苯胺基乙腈化工废水是一种高浓度难降解的有机废水，通过静置结晶法对原水进行预处理，然后采用兼氧-SBR工艺对稀释废水进行生化处理，并达到预期效果。     

生化后置催化铁内电解工艺处理化工废水的研究

某些化工废水经常规生化工艺处理后，出水的COD和色度值仍较高，直接采用混凝处理效果不理想，且对混凝剂的消耗量大。为此，考察了催化铁内电解作为生化后处理工艺的可行性及其作用。试验结果表明，将催化铁内电解置于生化工艺之后，其出水再经絮凝沉淀处理可以取得较好的脱色效果，对COD等污染物也有一定的去除作用，说明催化铁内电解法不但可以作为难降解化工废水的生化预处理工艺，还可作为生化后处理工艺。     

分质预处理强化制药废水处理效果的研究

采用活性污泥法/水解酸化/MBR工艺处理制药废水,分析了铁炭微电解强化预处理水量权重小、有机污染物含量高、生物毒性强的工段废水后,组合工艺对混合废水的处理效果。结果表明:制药废水具有较强的生物毒性,可通过好氧处理方法进行削减,两级好氧工艺可有效去除具有生物毒性废水中的氨氮;铁炭微电解可大幅降低有机污染物浓度并削减生物毒性,提高后续生物处理工艺对COD、NH4+-N的去除效果,试验原水的COD、NH4+-N、总氮分别为(6 000～8 000)、(50～100)、(100～200)mg/L,经铁炭微电解强化预处理工段废水后,组合工艺出水COD、NH4+-N、总氮分别降至500、5、60 mg/L以下,达到排入污水处理厂的要求。     

水力空化与生物法联用降解苯酚的试验研究

本试验将水力空化作为生物法处理含苯酚废水溶液的预处理工艺,研究了苯酚废水中COD的去除率,并与单独用生物法处理苯酚废水溶液后的COD去除率作对比,确定水力空化作为难降解废水预处理工艺的可行性。     

铁炭Fenton/SBR法处理硝基苯制药废水

为探寻硝基苯废水的适宜处理工艺，开展了铁炭Fentort／SBR工艺处理硝基苯制药废水的试验研究。结果表明，铁炭内电解结合Fenton氧化的预处理工艺可有效去除废水中的硝基苯类物质，并提高了废水的可生化性。当原水的pH值为2～3、H2O2投加量为500～600mg／L时，调节预处理出水pH值至7～8并经沉淀处理后，对COD和硝基苯类物质的总去除率分别可达47％和92％。后续混合废水经SBR工艺处理后出水水质能满足国家污水排放标准。     

维生素制药废水混凝-离心法预处理工程实践

对维生素制药废水进行混凝-离心法预处理,可以有效地分离出废水中的蛋白质,烘干后的蛋白质可用作饲料。预处理后的废水COD含量从约20 000 mg/L降至约8 000 mg/L,减轻了后续生化处理的负担。介绍了该预处理工艺和离心机的试验、运行情况,并对工艺运行效果进行了分析讨论。     

炼油废水的物化预处理工艺研究

对炼油废水的物化预处理工艺进行了研究，比较了分别投加5种不同混凝剂的混凝沉淀效果。结果表明：SHY-Ⅲ型混凝剂与PAM配合投加时对浊度和COD的去除效果最好；投加电解质CaCl2后破乳效果显著；混凝剂和CaCl2的投加量对混凝效果均有影响。对混凝沉淀出水采用气浮或超滤工艺进行处理可进一步去除废水中的乳化油，但对溶解性COD的去除作用微弱。经过物化预处理后，废水中大量有毒、难降解的有机物被去除，可生化性大大提高。     

化学强化预处理环氧丙烷废水的试验研究

以环氧丙烷废水为研究对象初步研究了H2O2预氧化作为化学强化预处理的最佳试验条件以及预氧化+生物接触氧化工艺处理的效果。结果表明,用H2O2预处理环氧丙烷废水取得了良好效果。经预处理后,COD总去除率可达到92%,提高了废水的可生化性。     

微电解/光触媒/催化/UASB/接触氧化处理化工废水

采用酸化反应/气浮/铁碳微电解/水解/氨氮吹脱/光触媒反应/催化氧化预处理工艺处理高浓度化工废水后,利用UASB/曝气池/水解酸化/接触氧化工艺处理综合废水,预处理规模为120 m~3/d,总处理量为250 m~3/d。运行实践表明,预处理工艺可明显降低高浓度废水的COD、NH_3-N和苯酚,整个工艺处理出水水质达到接管要求。     

微电解-混凝-SBR法处理焦化废水

采用微电解-混凝-SBR串联工艺处理焦化废水的试验结果表明，微电解-混凝(作为SBR工艺的预处理)能提高该废水的可生化性，同时使COD、酚、氰等污染物也得到了部分去除；预处理的适宜参数为：进水COD=1700～2400mg／L、pH=3．0～3．2、微电解柱的水力停留时间(HRT)=55～65min、Fe／C=1：1．5；经微电解-混凝-SBR串联工艺处理后，出水中酚、氰、COD、氨氮的浓度分别小于0．5、0.5、100、15mg／L，总去除率均在90％以上，达到了国家一级排放标准(GB13456-92)。     

Conditioning of wastewater sludge using freezing and thawing: role of curing

Freeze/thaw (F/T) treatment is an efficient pre-treatment process for biological sludges. When bulk sludge was frozen, tiny unfrozen regimes in the ice matrix were continuously dehydrated by surrounding ice fronts, termed as the “curing stage”. This work demonstrated that the F/T treatment could not only enhance sludge dewaterability, but also solubilize organic matters from sludge matrix. Most enhancement of sludge dewaterability was achieved during bulk freezing stage, with the waste activated sludge more readily dewatered than the mixed sludges after treatment. Conversely, the freezing stage released only limited quantities of organic matters to liquid. Conversely, the curing contributed mostly on chemical oxygen demand (COD) solubilization and NH₃-N release. The crystallization of intra-aggregate moisture was claimed to damage cell membranes so to release intracellular substances to surroundings. The F/T treatment with sufficient curing is advised to effectively condition biological sludge as the feedstock of the following anaerobic digestion process.     

Constructed wetland mesocosms for the treatment of diluted sugarcane molasses stillage from ethanol production using Pontederia sagittata

Sugarcane molasses stillage contains a very high concentration of organic matter and toxic/recalcitrant compounds. Its improper disposal has become a global problem and there is very scanty information about its treatment using phytotechnologies. This work aimed at evaluating the performance of subsurface flow constructed wetlands (SSF CWs) mesocosms planted with Pontederia sagittata and operating at two hydraulic retention times (HRTs), compared to an unplanted SSF CWs, for the treatment of diluted stillage subjected to no pre-treatment apart from an adjustment to pH 6.0. CWs were fed with very high surface COD loading rates (i.e. 47.26 and 94.83gCOD/m(2)d). The planted CWs were able to remove COD in the range of 80.24-80.62%, BOD(5) in the range of 82.20-87.31%, TKN in the range of 73.42-76.07%, nitrates from 56-58.74% and sulfates from 68.58-69.45%, depending on the HRT. Phosphate and potassium were not removed. It was concluded that this type of CWs is a feasible option for the treatment of diluted stillage.     

Treatment of olive oil mill wastewater by combined process electro-Fenton reaction and anaerobic digestion

In this work, we investigated an integrated technology for the treatment of the recalcitrant contaminants of olive mill wastewaters (OMW), allowing water recovery and reuse for agricultural purposes. The method involves an electrochemical pre-treatment step of the wastewater using the electro-Fenton reaction followed by an anaerobic bio-treatment. The electro-Fenton process removed 65.8% of the total polyphenolic compounds and subsequently decreased the OMW toxicity from 100% to 66.9%, which resulted in improving the performance of the anaerobic digestion. A continuous lab-scale methanogenic reactor was operated at a loading rate of 10 g chemical oxygen demand (COD)l(-1) d(-1) without any apparent toxicity. Furthermore, in the combined process, a high overall reduction in COD, suspended solids, polyphenols and lipid content was achieved by the two successive stages. This result opens promising perspectives since its conception as a fast and cheap pre-treatment prior to conventional anaerobic post-treatment. The use of electro-coagulation as post-treatment technology completely detoxified the anaerobic effluent and removed its toxic compounds.     

Removal of organic pollutants from industrial wastewater by electrogenerated Fenton's reagent

This study was performed to investigate the treatment of an industrial wastewater mainly containing naphthalene- and anthraquinone-sulphonic acids, by electrogenerated Fenton's reagent. The hydrogen peroxide was produced in situ by electrochemical reduction of oxygen on graphite-felt cathodes and the Fe2+ ions were also regenerated by cathodic reduction of Fe3+. The influence of cathode potential, Fe2+ concentration and electrode surface pre-treatment on chemical oxygen demand (COD) removal and colour fading were studied. Results indicated that the higher COD removal was obtained in the presence of 3 mM of ferrous ions working at a constant potential of -1 V vs. SCE. Moreover, it was shown that both chemical and electrochemical pre-treatments of the cathode surface resulted in a decrease of COD depletion.     

Behavior of inorganic elements during sludge ozonation and their effects on sludge solubilization

The behavior of inorganic elements (including phosphorus, nitrogen, and metals) during sludge ozonation was investigated using batch tests and the effects of metals on sludge solubilization were elucidated. A decrease of ∼50% in the ratio of sludge solubilization was found to relate to a high iron content 80-120 mgFe/gSS than that of 4.7-7.4 mgFe/gSS. During sludge ozonation, the pH decreased from 7 to 5, which resulted in the dissolution of chemically precipitated metals and phosphorus. Based on experimental results and thermodynamic calculation, phosphate precipitated by iron and aluminum was more difficult to release while that by calcium released with decrease in pH. The release of barium, manganese, and chrome did not exceed 10% and was much lower than COD solubilization; however, that of nickel, copper, and zinc was similar to COD solubilization. The ratio of nitrogen solubilization was 1.2 times higher than that of COD solubilization (R² = 0.85). Of the total nitrogen solubilized, 80% was organic nitrogen. Because of their high accumulation potential and negative effect on sludge solubilization, high levels of iron and aluminum in both sewage and sludge should be considered carefully for the application of the advanced sewage treatment process with sludge ozonation and phosphorus crystallization.     

Anaerobic treatment of fibreboard manufacturing wastewaters in a pilot scale hybrid usbf reactor.

The treatment of fibreboard manufacturing (FBM) wastewaters was carried out in an industrial pilot plant, which consisted of a hybrid upflow sludge bed filter (USBF) anaerobic reactor and a coagulation-flocculation unit as a pre-treatment. COD removal efficiencies of 90-93% were attained in the anaerobic reactor operating at 37degrees C at organic loading rates (OLR) of 6.5-8.5 kg COD/m3 d. Flocculant sludges were used as inoculum, and granulation was observed in the USBF reactor after 120 days of operation. The overall linear upward velocity (result of liquid and gas flow) was the key factor controlling biomass retention and, therefore, a stable operation at high OLR. According to ecotoxicity values (measured by means of bioluminescence assays), the wastewaters were partially detoxified, being EC50 values for the liquid effluent 25 times lower than those corresponding to the influent. Besides, phenolic compounds removal efficiencies of 90% were attained. The hybrid reactor configuration is an interesting alternative to treat these wastewaters since it is less sensitive to biomass clogging or floatation.     

A1-A2-O1-O2工艺处理焦化废水试验研究

采用A1-A2-O1-O2艺进行焦化废水处理试验,利用厌氧酸化作为预处理,反硝化-碳化-硝化作为二级生物处理,以COD作为主要污染物控制出水水质指标,试验结果表明,系统对COD和NH3-N的去除比较稳定,是一种经济而有效的焦化废水处理工艺。     

State detection and control of overloads in the anaerobic wastewater treatment using fuzzy logic.

The two-stage anaerobic wastewater pre-treatment was modelled and controlled. The biological state of the reactors could be predicted using a fuzzy logic system and based upon this, proper control actions were taken automatically in order to avoid an overload. The system was designed to handle very strong fluctuations in the concentration of the substrate and the volumetric loading rate. Hydrogen concentration together with methane concentration, gas production rate. pH and the filling level of the acidification buffer tank were used as input variables for the fuzzy logic system. The manipulated variables were the flow rate from the acidification buffer tank into the methane reactor, the temperature and pH of both reactors, the circulation rate of the fixed bed reactor, back flow from the methane reactor into the acidification, and the control of the feed into the acidification buffer tank. The developed control system was successfully tested on a fully automated lab scale two-stage anaerobic digester. Different types of wastewater from food processing industries were successfully applied. Even a restart of feeding with very high COD concentrations (100 gl(-1) after several days of stand by was handled successfully. Effluent concentrations could be kept low without using TOC, COD or equivalent measurements.     

MEMBRANE BIOREACTORS AND CONSTRUCTED WETLANDS FOR TREATMENT OF RENDERING PLANT WASTEWATER

The performance of a novel industrial membrane bioreactor (MBR) comprising denitrification, nitrification and ultrafiltration for the secondary treatment of primary treated animal rendering wastewater has been compared with an experimental, low-cost and novel vertical-flow constructed wetland planted with Typha latifolia L. (Reedmace or Broad-leaved Cattail). The process wastewater followed pre-treatment by dissolved air flotation (DAF). The mean DAF effluent gave highly variable chemical oxygen demand (COD) and ammonia concentrations of 5816 (standard deviation (SD): 3005.0) and 614 (SD: 268.7) mg/l, respectively. The mean MBR effluent for COD and ammonia was 37 and 86 mg/l, respectively. The mean treatment performance of the constructed wetland for COD, ammonia and suspended solids was 205, 67 and 57 mg/l, respectively.     

Pre-treatment optimisation studies for secondary effluent reclamation with reverse osmosis

Physical-chemical pre-treatment was used for the reverse osmosis unit for reclamation of secondary effluents. The pilot plant was equipped with a variety of tertiary treatment units to prevent fouling and biofouling of the cellulose-acetate reverse osmosis membranes used. The optimisation of pre-treatment involved application of various concentrations of lime to raise the pH to 10.3-12.1, and to stabilise the sludge generated, as well as different dosages of ferric chloride (15, 20, and 25 mg/L) for the coagulation and solid-liquid separation. Sodium hypochlorite (8 mg/L) and UV disinfection are used for microbiological control. The water quality obtained, under the optimum conditions (pH=10.5; FeCl(3): 25 mg/L; anionic flocculant: 0.5 mg/L; sodium hypochlorite: 8 mg/L) was high, showing an average conductivity of 66 microS/cm and low COD values 4 mg O(2)/L. The product water is suitable for injection into a groundwater aquifer to counteract seawater intrusion.