Study of prediction for groundwater contamination in wastewater land treatment system

This paper uses a prediction model of groundwater pollution based on the experiments in the laboratory and in field .The model, which was tested and calibrated by the field observated data ,satisfactorily simulated the field conditions in land treatment system of wastewater . Particularly , the model can provide the reliable pollution prediction of heavy metals , organisms and nitrogen . The model was used to predict the groundwater pollution caused by the land treatment system in the region of North China . The calibration of the model showed that correlation coefficients between the tested and predictive data of Cr6+. As3+, organism and NH4+ could reach 0.990, which proved that the model possessed the realistic instructive significance for design and use of wastewater land treatment systems .     

Simulation and control strategy for the variational influent of WWTP

With the development of activated sludge model, the simulation software for the design and operation of wastewater treatment plant （WWTP） was produced and has been widely used. The dynamic change of the quality and flow of influent are major factors causing the unstable operation of wastewater treatment process. As a basic model, ASMI model was used for the simulation of activated sludge process, and double exponential model was selected for the simulation of secondary sedimentation tank. The influences of influent change to the aeration tank and secondary sedimentation tank were investigated, and the relationship among influent change, the quality of effluent and the level of sludge blanket in secondary sedimentation tank was established. On the basis of the simulation results, the operation of the WWTP could be adjusted under the dynamic change of the influent. Furthermore, the controlling strategy combined the feed-forward on the influent flow and the feedback on the level of sludge blanket in the secondary sedimentation tank was studied.     

Settling basin design in a constructed wetland using TSS removal efficiency and hydraulic retention time

Using total suspended solid （TSS） removal efficiency and hydraulic retention time （HRT） as design parameters a design guideline of a settling basin in a constructed wetland （CW） was suggested; as well as management of sediment and particle in the settling basin. The CW was desiEned to treat the piggery wastewater effluent from a wastewater treatment plant during dry days and stonnwater runoff from the surrounding paved area during wet days. The first settling basin （FSB） in the CVV was theoretically designed with a total storage volume （TSV） of 453 ms and HRT of 5.5 hr. The amount of sediment and particles settled at the FSB was high due to the sedimentation and interception of plants in the CVV. Dredging of sediments was performed when the retention rate at the FSB decreased to approximately 80%. Findings showed that the mean flow rate was 21.8 m3/hr less than the designed flow rate of 82.8 m3/hr indicating that the FSB was oversize and operated with longer HRT （20.7 hr） compared to the design HRT. An empirical model to estimate the length of the settling basin in the CW was developed as a function of HRT and desired TSS removal efficiency. Using the minimum tolerable TSS removal efficiency of 30%, the length of the FSB was estimated to be 31.2 m with 11.8 hr HRT.     

Micro-electrolysis technology for industrial wastewater treatment

Experiments were conducted to study the role of micro-electrolysis in removing chromaticity and COD and improving the biodegradability of wastewater from pharmaceutical.dye-printing and papermaking plants.Results showed that the use of micro-electrolysis technology could remove more than 90% of chromaticity and more than 50% of COD and greatly improved the biodegradability of pharmaceutical wastewater.Lower initial pH could be advantageous to the removal of chromaticity. A retention time of 30 minutes was recommended for the process design of micro-electrolysis.For the use of micro-electrolysis in treatment of dye-printing wastewater,the removal rates of both chromaticity and COD were increased from neutral condition to acid condition for disperse blue wastewater;more than 90% of chromaticity and more than 50% of COD could be removed in neutral condition for vital red wastewater.     

Flocculation performance of a novel synthesized flocculant with low ecological risk

Combined flocculants with low ecological risk are urgently required in water supply and wastewater treatment in China. A novel flocculant was thus developed under the condition of low ecological risk( noted as CAS).The experiments to examine wastewater treatment performance of the new product showed that there was favourable performance in the flocculation process in contrast to commercial flocculants in treating kaolin suspensions, municipal effluent and domestic wastewater. Flocculation performance included the turbidity removal rate, sediment character and a decrease in COD(chemical oxygen demand). The sediment time of flocculation is short and the removal rate of turbidity treated by CAS is high compared with PAC(polyaluminum-chloride), PAM (polyacrylamide) and the combined addition of PAC and PAM. The optimal concentration required to affect flocculation processes is dependent on kaolin concentration and the character of the wastewater within the range examined. It also showed that CAS is effective to treat wastewater with high turbidity.     

Approaches to municipal wastewater irrigation and environmental protection

To reuse the water and nutrient resources from ecological point of view the goals, criteria and constraint conditions of the scientifically municipal wastewater irrigation are discussed as well as the practice in major municipal wastewater irrigation areas in China is introduced, of which particularly the effects of municipal water irrigation mixing with oil refinery wastewater on the agricultural ecosystem are studied and described. It has been revealed that benzo(a)pyrene in various parts of paddy crop is attributed to air pollution, water-soil pollution and biosynthesis of plant. Of exogenous contributions of benzo(a)pyrene in paddy shoot system under natural condition, the dominant factor is the air pollution, whereas the water-soil factor is considered to be secondary. Therefore, it is mostly urgent to control the air pollution source of benzo(a)pyrene, to which the edible parts of various green plants are exposed directly.     

Removal of antibiotics in a parallel-plate thin-film-photocatalytic reactor: Process modeling and evolution of transformation by-products and toxicity

Photocatalytic degradation of sulfamethoxazole(SMX) antibiotic has been studied under recycling batch and homogeneous flow conditions in a thin-film coated immobilized system namely parallel-plate(PPL) reactor. Experimentally designed, statistically evaluated with a factorial design(FD) approach with intent to provide a mathematical model takes into account the parameters influencing process performance. Initial antibiotic concentration, UV energy level, irradiated surface area, water matrix(ultrapure and secondary treated wastewater) and time, were defined as model parameters. A full of 2~5 experimental design was consisted of 32 random experiments. PPL reactor test experiments were carried out in order to set boundary levels for hydraulic, volumetric and defined defined process parameters. TTIP based thin-film with polyethylene glycol + TiO_2 additives were fabricated according to pre-described methodology. Antibiotic degradation was monitored by High Performance Liquid Chromatography analysis while the degradation products were specified by LC–TOF-MS analysis. Acute toxicity of untreated and treated SMX solutions was tested by standard Daphnia magna method. Based on the obtained mathematical model, the response of the immobilized PC system is described with a polynomial equation. The statistically significant positive effects are initial SMX concentration,process time and the combined effect of both, while combined effect of water matrix and irradiated surface area displays an adverse effect on the rate of antibiotic degradation by photocatalytic oxidation. Process efficiency and the validity of the acquired mathematical model was also verified for levofloxacin and cefaclor antibiotics. Immobilized PC degradation in PPL reactor configuration was found capable of providing reduced effluent toxicity by simultaneous degradation of SMX parent compound and TBPs.     

Pilot-scale experiments on multilevel contact oxidation treatment of poultry farm wastewater using saran lock carriers under different operation model

A pilot-scale multilevel contact oxidation reactors system, coupled with saran lock carriers,was applied for the treatment of poultry farm wastewater. The removal efficiencies of CODcr, ammonia, and the total nitrogen as well as the elimination performance of CODcr and total nitrogen along the three-level contact oxidation tanks under six designed operational models were investigated. Based on the performance of the nitrogen removal of the saran lock carriers and the distribution of anoxic–aerobic interspace under the suitable operation model, the mechanism of nitrogen removal of the system was also explored. The results revealed that the intermittent aeration under parallel model is the most suitable operation model, while the removal efficiencies of CODcr, ammonia, and the total nitrogen were 86.86%, 84.04%, and 80.96%, respectively. The effluent concentration of CODcr,ammonia, and the total nitrogen were 55.6 mg/L, 8.3 mg/L, and 12.0 mg/L, which satisfy both the discharge standard of pollutants for livestock and poultry breeding industry(GB18596–2001) and the first grade of the integrated wastewater discharge standard(GB 8978–1996). Moreover, the mechanism for the nitrogen removal should be attributed to the plenty of anoxic–aerobic interspaces of the biofilm and the three-dimensional spiral structure of the saran lock carriers, where the oxygen-deficient distribution was suitable for the happening of the simultaneous nitrification and denitrification process. Therefore, the multilevel contact oxidation tanks system is an effective pathway for the treatment of the poultry farm wastewater on the strength of a suitable operation model and novel carriers.     

An innovative integrated oxidation ditch with vertical circle (IODVC) for wastewater treatment

The oxidation ditch process is economic and efficient for wastewater treatment, but its application is limited in case where land is costly due to its large land area required. An innovative integrated oxidation ditch with vertical circle(IODVC) system was developed to treat domestic and industrial wastewater aiming to save land area. The new system consists of a single-channel divided into two ditches(the top one and the bottom one by a plate), a brush,and an innovative integral clarifier. Different from the horizontal circle of the conventional oxidation ditch, the flow of IODVC system recycles from the top zone to the bottom zone in the vertical circle as the brush is running, and then the IODVC saved land area required by about 50% compared with a conventional oxidation ditch with an intrachannel clarifier. The innovative integral clarifier is effective for separation of liquid and solids, and is preferably positioned at the opposite end of the brush in the ditch. It does not affect the hydrodynamic characteristics of the mixed liquor in the ditch, and the sludge can automatically return to the down ditch without any pump. In this study, experiments of domestic and dye wastewater treatment were carried out in bench scale and in full scale, respectively. Results clearly showed that the IODVC efficiently removed pollutants in the wastewaters, i.e., the average of COD removals for domestic and dye wastewater treatment were 95 % and 90%, respectively, and that the IODVC process may provide a cost effective way for full scale dye wastewater treatment.     

Kinetic study on photocatalytic degradation of Acid Orange 52 in a baffled reactor using TiO2 nanoparticles

In this study, a baffled photocatalytic reactor was used for the treatment of colored wastewater containing the azo dye of Acid Orange 52(AO52). A study on the active species of the photocatalytic process using TiO_2 nanoparticles indicated that hydroxyl radical and superoxide have the greatest contribution to the dye degradation process respectively.Given that a level of biological oxygen demand/chemical oxygen demand(BOD5/COD) equal to 0.4 was achieved after about 5 hr from the beginning of the experiment, the reactor seems to be capable of purifying the wastewater containing AO52 dye after this time in order to discharge into a biological treatment system to continue the treatment process.The results of the liquid chromatography-mass spectrometry(LC-MS) test showed that during the first 4 hr of the experiment, with the breakdown of the azo bond, the contaminant was decomposed into the benzene annular compounds with less toxicity indicating a reduction in the toxicity of wastewater after removing the dye agent. The study on the kinetics of these reactions followed the pseudo-first-order kinetic model in all conditions and corresponded well to Langmuir–Hinshelwood model. According to the kinetic model for the simultaneous occurrence of possible pathways, the kinetic constant of production and degradation of intermediate products in optimal conditions was estimated to be between 0.0029 and 0.0391 min~(-1).     

长江中下游某Unitank污水处理厂去除雌激素的效果分析

以长江中下游地区某实际运行的Unitank污水处理厂为研究对象,跟踪监测了其进、出水类固醇雌激素(SE)的浓度水平,考察了雌激素去除效果随时间的变化规律,并分析了不同处理工段对雌激素去除的贡献。结果表明:污水厂进水中雌酮(E1)、17β-雌二醇(E2)、17α-乙炔基雌二醇(EE2)的浓度分别为32.4～89.0,19.4～78.0和12.3～45.0 ng/L,且夏季浓度高于冬季;Unitank工艺对E1、E2、EE2的去除率分别为21.3%～77.0%,23.4%～73.5%和25.2%～68.1%。SE去除主要依靠好氧生物降解实现,物理沉降(沉砂或沉淀)对SE的去除贡献较小。温度是影响SE去除的重要因素之一,较高的温度有利于SE的去除。     

Cadmium in sewage sludge in a Swedish region: sources and reduction opportunities

To create a more sustainable future, one of the Swedish government's aims is to close the eco-cycles between urban consumption areas and arable land. Increasing the use of sewage sludge from municipal wastewater treatment plants (MWTPs) is one method of achieving this goal. However, the use of sewage sludge is often prohibited due to its high concentrations of cadmium. As a consequence, large amounts of sewage sludge are deposited each year in landfills. This disposal has become more expensive for local authorities due to a new deposit tax introduced in the year 2000. Based on a survey of cadmium sources to MWTPs in a Swedish region this paper focuses on opportunities local authorities in Sweden have to influence the occurrence of cadmium in the sewage sludge. The results from the study show that cadmium in sewage sludge originates from diffuse sources, which are hard for local authorities to influence by direct means. This is most obvious for sources of cadmium in wastewater from households, which causes about one-third of the inflow of cadmium to MWTPs. Thus, the local authorities' possibilities are, in general, still restricted to downstream actions (such as disconnecting identified industrial sources and reconstructing the sewage system to further separate collection of wastewater and storm water). Local authorities could also implement changes in the process at the MWTP or an extended treatment of the sewage sludge generated. Nonetheless, these possible measures do not provide a sustainable solution to the cadmium issue since the origins of the sources remain. Hence, long-term strategies - outside of the scope of local authorities - need to focus on a general decrease of cadmium in society. However, increased knowledge about the distribution among different sources of cadmium to MWTPs may encourage local authorities to establish priorities for measures that will improve the quality of the sewage sludge.     

Cadmium in sewage sludge in a Swedish region: sources and reduction opportunities

To create a more sustainable future, one of the Swedish government’s aims is to close the eco-cycles between urban consumption areas and arable land. Increasing the use of sewage sludge from municipal wastewater treatment plants (MWTPs) is one method of achieving this goal. However, the use of sewage sludge is often prohibited due to its high concentrations of cadmium. As a consequence, large amounts of sewage sludge are deposited each year in landfills. This disposal has become more expensive for local authorities due to a new deposit tax introduced in the year 2000. Based on a survey of cadmium sources to MWTPs in a Swedish region this paper focuses on opportunities local authorities in Sweden have to influence the occurrence of cadmium in the sewage sludge. The results from the study show that cadmium in sewage sludge originates from diffuse sources, which are hard for local authorities to influence by direct means. This is most obvious for sources of cadmium in wastewater from households, which causes about one-third of the inflow of cadmium to MWTPs. Thus, the local authorities’ possibilities are, in general, still restricted to downstream actions (such as disconnecting identified industrial sources and reconstructing the sewage system to further separate collection of wastewater and storm water). Local authorities could also implement changes in the process at the MWTP or an extended treatment of the sewage sludge generated. Nonetheless, these possible measures do not provide a sustainable solution to the cadmium issue since the origins of the sources remain. Hence, long-term strategies — outside of the scope of local authorities — need to focus on a general decrease of cadmium in society. However, increased knowledge about the distribution among different sources of cadmium to MWTPs may encourage local authorities to establish priorities for measures that will improve the quality of the sewage sludge.     

构建污水处理厂现代生产管理模式（TPM）

结合本企业生产运行管理需求,从现有污水处理厂生产管控中存在的问题;生产运营管理模式设计原则及TPM生产管理组织模式的设计,阐述了构建污水处理厂现代生产管理模式的设想。     

四环素生产废水的生物流化床处理工艺设计

以好氧生物处理的基本原理为基础 ,推导了生物流化床工艺的动力学模型 ,并通过试验确定了该工艺用于处理四环素、洁霉素废水的动力学参数 ,从而为生物流化床处理四环素废水的工艺设计提供了依据。     

印染集中区水网络优化研究

耗水量大、水环境污染严重是印染集中区的一个突出问题.本文建立水网络数学模型,对印染集中区用水排水网络进行系统规划,该模型以集中区总成本最低为目标函数,模拟了以多级组合工艺为特点的污水处理设施数学模型.运用该模型对东北某印染集中区水网络进行设计和优化改进,在保证废水达标排放、成本最低的条件下,构建了企业内及企业间最佳回用网络,确定了污水处理设施工艺最优方案,并明确各级处理工艺中不同品质的处理水回用集中区企业的最优途径,为集中区内污水处理设施提标改造计划提供参考.研究结果表明：该模型在工业集中区或工业园用水规划及废水减量方面具有实用价值和较好的应用前景.     

中水回用对社区景观水体叶绿素a变化的影响

由于中水的营养盐含量较高,以中水为补水水源的社区景观水体存在较大的水华暴发风险.基于中水回用于景观水体的换水控制实验,建立了中水景观水体的富营养化模型,模拟了连续换水时和终止换水后叶绿素a的变化过程,分析了中水水质和换水周期对水体藻类生长的影响.结果表明,提高中水水质可以降低水体的叶绿素a峰值;在连续换水期,随着换水周期的缩短, 水体的叶绿素a峰值降低,并且从开始换水至达到峰值的时间增长;在连续换水期后终止换水,叶绿素a会重新达到峰值,并且原来的换水周期越短,水体的叶绿素a峰值反而越高,达到峰值所需时间越长.模型应用可为中水回用于社区景观水体的水量水质设计与维护提供依据.     

Simulation and analysis of wastewater stabilization Pond system

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细胞自动机模拟活性污泥法污水处理过程

从活性污泥法污水处理过程的微观机理出发,建立了污水处理过程的二维细胞自动机模型,并进行仿真实验.结果表明：建立的细胞自动机模型能够实现污水处理过程的动态可视化,复现出了污水中有机物被吸附、降解及微生物生长、繁殖和衰亡的过程;仿真中还讨论了污泥颗粒粒径、有机物分子半径、温度和污泥浓度等因素对模拟结果的影响,因素灵敏度分析...     

含油废水深度处理后回用于港区除尘系统的设计与运行

介绍了某港区作业区利用处理后的含油废水深度处理后回用于港口煤炭除尘系统工程的设计、运行和管理。该系统设计处理量为400m^3／d。采用了水解酸化预处理 生物接触氧化 生物活性炭的处理工艺流程，处理后的污水主要用于港区煤炭储存场冲洗地面、洒水抑尘等。