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This study was performed to increase the treatment efficiency and to reduce operation and maintenance costs of the existing nightsoil treatment plant. The existing nightsoil plant was not established by the nitrogen removal process, and was operated ineffectively with deterioration of treatment efficiency rate, and according to the demand of many operators, the expenses of operation and maintenance have become excessive. Modified plant has been changed through two steps. The first step, liquid decayed tank using closed oxidation ditch is operated to increase retention time only for nitrification. The second step, modified liquid decayed tank including anoxic tank is operated, it has an excellent nitrogen removal rate. In first step, when HRT was increased from 10 days to 13 days in liquid decayed tank including aeration tank using closed oxidation ditch, TN concentration of effluent appeared below 51 mg/L less than discharge limit, 60 mg/L. In second step, when anoxic tank and oxic tank were installed, HRT has been increased to 13 days and 26 days, respectively. Then average TN concentration of effluent was detected less than 13 mg/L for over one year. The simple process modified the existing two processes resulted in the reduction of costs for operation and maintenance in the personnel, chemical, and filter change sphere. 相似文献
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Automatic control for do and pH in the activated sludge process in a coke wastewater treatment plant
《Water science and technology》1998,37(12):141-148
The objective of this study is to develop an automatic control system for dissolved oxygen (DO) and pH of the activated sludge process in a coke wastewater treatment plant. A discrete type autotuned proportional-integral (PI) controller using an auto-regressive exogenous (ARX) model as a process model was developed to maintain the DO concentration in aerators by controlling the speed of surface aerators. Also a nonlinear pH controller using the titration curve was used to control the pH of influent wastewater. This control system was tested in a pilot scale plant. During this pilot plant experiment, there was small deviation of pH and the electric power consumption of surface aerators was reduced up to 70% with respect to the full operation when the DO set point was 2 mg/1. For real plant operation with this system, the discrete PI controller showed good tracking for set point change. The electricity saving was more than 40% of the electricity consumption when considering surface aerators. As a result of maintaining the DO constantly at the set point by the automatic control system, the fluctuation of effluent quality was decreased and overall improvement of the effluent water quality was achieved. 相似文献
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Operation of a new sewage treatment process with technologies of excess sludge reduction and phosphorus recovery. 总被引:1,自引:0,他引:1
This paper shows the potential application of a new sewage treatment process with technologies of excess sludge reduction and phosphorus recovery. The process incorporated ozonation for excess sludge reduction and crystallisation process for phosphorus recovery to a conventional anaerobic/oxic (A/O) phosphorus removal process. A lab-scale continuous operation experiment was conducted with the ratio of sludge flow rate to ozonation tank of 1.1% of sewage inflow under 30 to 40 mgO3/gSS of ozone consumption and with sludge wasting ratio of 0.34% (one-fifth of a conventional A/O process). Throughout the operational experiment, a 60% reduction of excess sludge production was achieved in the new process. A biomass concentration of 2300 mg/L was maintained, and the accumulation of inactive biomass was not observed. The new process was estimated to give a phosphorus recovery degree of more than 70% as an advantage of excess sludge reduction. The slight increase in effluent COD was observed, but the process performance was maintained at a satisfactory level. These facts demonstrate an effectiveness of the new process for excess sludge reduction as well as for phosphorus recovery. 相似文献
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L W Gill C O'Suilleabhain B D R Misstear P Johnston T Patel N O'Luanaigh 《Water science and technology》2008,57(12):1921-1926
The performance of six separate percolation areas has been intensively monitored to ascertain the attenuation effects of the unsaturated subsoil with respect to on-site wastewater effluent. Septic tank effluent on three sites and secondary treated effluent on the other three sites was discharged into subsoils of varying percolation values. Samples of the percolating effluent were taken using suction lysimeters installed to nominal depths of 0.3, 0.6 and 1.0 m below the invert of the percolation trenches. The results clearly showed that the development of a biomat across the percolation areas receiving secondary treated effluent was muted on these sites compared to the sites receiving septic tank effluent. Significant differences were found between the sites receiving septic tank and secondary treated effluent in terms of the potential nitrogen loading to groundwater. The average nitrogen loading after 1.0 m depth of unsaturated subsoil per capita equated to 5.5, 3.3 and 3.2 gTotal-N/d for the sites receiving secondary treated effluent compared to 4.2, 1.7 and 0.3 gTotal-N/d for the sites receiving septic tank effluent. The noticeably higher nitrogen loading on one of the septic tank sites corresponded to the effluent percolating through highly permeable subsoil that counteracted any significant denitrification. 相似文献
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沉淀池生物污泥回流工艺生物强化作用的研究 总被引:2,自引:0,他引:2
利用生物预处理出水中携带的硝化细菌和异养细菌等微生物,在后续沉淀单元产生生物延伸效应,并通过采取沉淀池生物污泥回流强化措施,使沉淀池在去除浊度的同时,产生类似活性污泥法的作用,强化生物净化作用.在增加生物污泥回流前、后,沉淀池出水CODMn平均分别为4.16mg/L、2.72 mg/L,沉淀池出水相对生物预处理出水CODMn的平均去除率由4.65%提高至31.4%,去除效果显著提高.同时,增加生物污泥回流后,对浊度和氨氮的去除也得到进一步的改善. 相似文献
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An ethanol-methane coupled system was proposed to resolve wastewater pollution in cassava ethanol production. The wastewater originated from ethanol distillation is treated with two-stage anaerobic digestion and then recycled for medium preparation for the next batch ethanol fermentation, thus eliminating wastewater discharge and saving fresh water. The constituents of the two-stage anaerobic digestion effluent were complex which influenced the ethanol fermentation performance. This paper aimed to study the effect of two constituents in the effluent, i.e. sulfide and ammonia, on cassava-based ethanol fermentation performance. It was found that sulfide reduced the consumption rate of total sugar by significantly inhibiting the growth of Saccharomyces cerevisiae, but the total consumption amount of total sugar at the end of fermentation was not influenced. S. cerevisiae produced more glycerol and less ethanol at the end of fermentation containing higher concentration of sodium sulfide. Ethanol fermentation performance could be hardly influenced by the sulfide in the two-stage effluent because of the very low concentration. More glycerol was produced while final ethanol concentration was reduced when the level of ammonia in the two-stage effluent was higher. 相似文献
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An easy-to-implement controller based on gas phase measurements for anaerobic digestion processes was developed. The controller is based on the indirect control of COD in the effluent by means of controlling the hydrogen concentration in the biogas. The fast response of hydrogen under destabilizations, such as those caused by overloads, guarantees an early actuation on the system before it destabilizes. The controller is designed such that it brings the anaerobic digestion process to maximum capacity by pushing it to maximum methane production as long as hydrogen remains low. Experiments have been conducted to test the controller under organic over- and underload situations and promising performance was achieved. Further experiments must be carried out to validate the controller under a wider spectrum of situations to enable its robust industrial application. 相似文献
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厌氧—接触氧化渠—垂直潜流型人工湿地处理农村生活污水研究 总被引:2,自引:0,他引:2
选择厌氧—接触氧化渠—垂直潜流型人工湿地工艺处理农村生活污水,分析比较了各工艺段DO水平,接触氧化渠充氧效果明显.通过对COD、NH3—N和TP浓度及去除率的研究发现,厌氧池去除率较稳定,对各污染物去除率最高可达72%、49.54%和66.36%,接触氧化渠和人工湿地对各污染物也有较高去除率,但并不稳定.系统运行稳定后,出水水质整体可达到《城镇污水处理厂污染物排放标准》(GB 18918-2002)二级标准,部分时段可达一级B标准. 相似文献
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微孔曝气器充氧性能变化对污水处理厂能耗的影响 总被引:3,自引:0,他引:3
以北京小红门污水处理厂的新、旧刚玉盘式微孔曝气器为例,进行曝气充氧性能的试验研究,并分析了更换曝气器对污水处理厂能耗的影响。结果表明:经过长期使用的曝气器充氧性能下降较大,氧总转移系数、氧的利用效率和动力效率分别下降了57%、58%和59%。旧微孔曝气器氧的利用效率为8.9%~14.1%,略高于中大气泡曝气器的性能参数,但由于微孔曝气器具有较大的阻力损失,使旧微孔曝气器的动力效率为1.5~2.1kgO2/(kW.h),低于中大气泡曝气器的性能参数。更换小红门全厂1/4的微孔曝气器后,鼓风机单耗降低21%,全厂能耗降低12%。因此,当微孔曝气器的充氧性能下降较大时,更换新的曝气器具有较高的节能和经济效益。 相似文献
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A A Andrade P M Glória J V H d'Angelo D O Perissotto R A Lima 《Water science and technology》2007,55(6):199-204
The main objective of this work is to study the technical viability of using the effluent generated in paper machines (white water) in the wash presses of the bleaching stage, reducing fresh water consumption. As a case study, the industrial process of Ripasa S.A. Celulose e Papel was evaluated. White water rate is about 700 m3/h and it is not possible to reuse all this volume in the bleaching stage without causing operational problems (fouling in tubes and clogging in the screens). A mass balance of the bleaching unit was developed in an electronic spreadsheet in order to evaluate the possibility of reducing fresh water consumption, using only a fraction of the available white water in the wash presses. To achieve this objective some physical-chemistry properties of the white water stream and of other streams of the process were determined. The maximum concentration of some non-process elements (Si, Ca, Mn and Fe), which could accumulate in the process, were determined in order to establish some parameters to allow process integration of the streams involved, considering operational constraints. The results obtained have shown that it is possible to reduce approximately by 13% the consumption of fresh water and this methodology has been satisfactory. 相似文献
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Based on a comprehensive cost analysis for the expansion of the Finnentrop WWTP, integration of lamella separators in the biological treatment stage was given priority as optimal solution to increase the solids concentration. The overall expansion project included the reconstruction of the former primary clarifier into a primary settling tank with short retention times and the use of the remaining volume for pre-denitrification. Four lamella separators were positioned in the existing carousel-type activated sludge tank. With the lamella assemblies ensuring it was possible to continue operation of the existing secondary settling tanks. To control an adequate solids concentration in the activated sludge tank and to avoid any overloading of the secondary settling tank, a newly developed bypass strategy was applied. With a controlled mixing of direct effluent from the lamella separators and the contents of the activated sludge tank, the solids concentration of the influent to the secondary settling tank could be maintained at a value of 2.2 kg/m(3). The lamella separator concept did not account for any significant changes in the sludge characteristics, and the overall elimination of nutrients and organic carbon was found to be excellent upon optimisation of the operational lamella strategy. 相似文献
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采用标准κ-ε模型和VOF模型及欧拉模型对泄洪洞及掺气设施水力特性进行了三维数值模拟计算。主要计算了自由水面、掺气设施水力特性和空腔特性及坎后沿程渠底板中心线的掺气浓度。计算结果表明,VOF模型和欧拉模型可以在一定程度上模拟掺气设施水力特性和空腔形态等水力参数。总体而言,在对泄洪洞掺气设施的数值模拟方面,欧拉模型在一定程度上比VOF模型有更好的模拟精度。利用数值模拟可提高水利设计效率和节省费用,并为模型试验提供前期预测和指导,同时其结果可以作为模型试验补充和完善的依据,本文所采用的数值模拟方法及研究结果可供类似工程的研究参考。 相似文献