Application of remote monitoring and automatic control system using neural network for small wastewater treatment plants in Korea.

For this study, an automatic control system has been developed by using a neural network and internet-based remote monitoring system for efficient operation of plants that have a serious variance of influent loading and have difficulties in appropriate maintenance, just like small wastewater treatment plants in Korea. In the control algorithm, ORP was used as the main sensor for control. At the point where the ORP value was judged to reach the "nitrate knee" of denitrification and phosphorus release, ORP indicated the state of lower saturation read by the neural network and then changed the operating condition from the reduction state to the oxidation state. For example, if ORP indicates the state of higher saturation at the point of "nitrogen breakpoint" or "ammonia valley" of nitrification, the neural network reads it and cuts off the oxygen supply and mixing. The dORP data have been used as one of the main input for the neural network. After the operation of lab-scale cyclic aeration process using an automatic control system, it has been found that regardless of loading variance, more than 95% of organic matters and more than 60% of nitrogen and phosphorus have been removed. Assuming that an internet-connected computer and a basic web browser are available, this study has developed a remote monitoring system that can monitor the operating status of small plants or any troubles with them.     

Performance evaluation of the BioCAST technology: a new multi-zone wastewater treatment system

A new wastewater treatment technology, called BioCAST, has been designed and developed for high rate and simultaneous removal of organic carbonaceous compounds as well as nitrogen and phosphorus, along with reduced sludge generation. The treatment system has two interlinked reactors containing four independent zones with different environmental conditions of aerobic, microaerophilic, anoxic and anaerobic for the biological treatment of wastewater, as well as two clarification zones and a filtration unit for solid-liquid separation. The treatment system contains suspended as well as fixed-film microorganisms. The performance evaluation of the BioCAST system was carried out at organic loading rates of 0.95 to 1.86 kg/m(3) d, and nitrogen and phosphorus loading rates of 0.02 to 0.08 kg/m(3) d and 0.014 to 0.02 kg/m(3) d, respectively. The results demonstrated high removal efficiencies of carbon and nitrogen throughout the operation period, reaching 98.9 and 98.3%, respectively. Phosphorus removal efficiency was lower than 50% during the first 160 days of operation but it increased with the increase of nitrogen loading rate above 0.05 kg/m(3) day and concomitant reduction of C/N ratio below 15. Phosphorus removal efficiency reached 94.1%, producing an effluent concentration of 1.4 mg/L after 225 days of operation. The overall biomass yield based on the consumed COD was 3.7%.     

投加短管填料对活性污泥工艺性能的改善

在传统活性污泥工艺中投加聚氯乙烯短管填料,研究投加短管填料对活性污泥工艺性能的影响,将该系统应用于城市污水处理试验研究,并与单一活性污泥系统进行对比研究。结果表明,投加短管填料可以改善活性污泥工艺性能,系统对有机物及氮、磷去除效果显著,可在同一反应器内实现脱氮除磷。与活性污泥系统相比,投加短管填料反应器具有较强的抗冲击负荷能力。     

人工湿地生态系统脱氮除磷机理及研究进展

介绍了人工湿地生态系统去除污水中氮磷的机理,并从工艺优化、湿地植物、基质和微生物四个方面系统地阐述了目前人工湿地系统提高氮磷去除率的研究进展情况;通过优化湿地系统设计、湿地植物的筛选、基质的选择和复合、微生物种群的调控等可以有效提高人工湿地的氮磷去除率,提出了当前人工湿地研究中存在的问题和研究方向.     

A two-sludge system for simultaneous biological C, N and P removal via the nitrite pathway

Nitrogen removal via the nitrite pathway results in significant savings in both aeration costs and COD requirements for denitrification when compared to the conventional biological nitrogen removal process. Implementation of the nitrite pathway for simultaneous C/N/P removal in a single sludge system has a major drawback: the aeration phase disfavours denitrifying phosphorus removal. A possible configuration to overcome this issue is the utilisation of a two-sludge system where autotrophic and heterotrophic populations are physically separated. This paper experimentally demonstrates the feasibility of a nitrite-based two-sludge system with sequencing batch reactors (SBR) for the treatment of urban wastewater: a heterotrophic SBR with denitrifying PAOs for P removal and an aerobic SBR for N removal. Partial nitrification was attained in the autotrophic SBR so that shortcut biological nitrogen removal was achieved by using the anoxic dephosphatation activity of DPAOs. Finally, the effect of operating this system without pH control was studied using different influent pH values (pH = 6.8, 7.5 and 8.2) and, despite some efficiency lost due to the pH fluctuations, the system was able to remove most of the C, N and P present in the wastewater.     

Upgrading of existing aerobic plants with the LUCAS anaerobic system based on full-scale experiences.

It has been demonstrated that the combination of anaerobic-aerobic treatment is the best technological and economical solution for the treatment of high loaded wastewater. Where in the past aerobic treatment systems were still very acceptable due to the very good treatment efficiency, simplicity and robustness of the technology, this has, in most cases, been changed due to very stringent sludge disposal legislation. The anaerobic pretreatment takes care of approximately 80-90% of the overall treatment efficiency at high loading rates and low sludge production and low energy costs. The aerobic posttreatment takes care of the absolute high removal efficiency and nitrogen and phosphorus removal. Because of the low organic loading rate of the aerobic posttreatment also in this stage the sludge production is low. The combination of anaerobic-aerobic treatment results in a compact system capable of reaching high treatment efficiency at low sludge production and lower energy consumption. Waterleau Global Water Technology has developed LUCAS anaerobic-aerobic system that combines an Upflow Anaerobic Sludge Blanket (UASB) reactor with an aerobic, constant-level cyclic activated sludge system, which is very suitable for the treatment of high loaded wastewaters in general and brewery waste water in particular. It has been proven from several full scale upgrading projects that the UASB system is best suitable for implementation in the aerobic plants that have to be extended in capacity.     

Wastewater treatment with submerged fixed bed biofilm reactor systems--design rules, operating experiences and ongoing developments.

Wastewater treatment systems using bio-films that grow attached to a support media are an alternative to the widely used suspended growth activated sludge process. Different fixed growth biofilm reactors are commercially used for the treatment of municipal as well as industrial wastewater. In this paper a fairly new fixed growth biofilm system, the submerged fixed bed biofilm reactor (SFBBR), is discussed. SFBBRs are based on aerated submerged fixed open structured plastic media for the support of the biofilm. They are generally operated without sludge recirculation in order to avoid clogging of the support media and problems with the control of the biofilm. Reactor and process design considerations for these reactors are reviewed. Measures to ensure the development and maintenance of an active biofilm are examined. SFBBRs have been applied successfully to small wastewater treatment plants where complete nitrification but no high degree of denitrification is necessary. For the pre-treatment of industrial wastewater the use of SFBBRs is advantageous, especially in cases of wastewater with high organic loading or high content of compounds with low biodegradability. Performance data from exemplary commercial plants are given. Ongoing research and development efforts aim at achieving a high simultaneous total nitrogen (TN) removal of aerated SFBBRs and at improving the efficiency of TN removal in anoxic SFBBRs.     

Enhanced P, N and C removal from domestic wastewater using constructed wetland employing construction solid waste (CSW) as main substrate

Construction solid waste (CSW), an inescapable by-product of the construction and demolition process, was used as main substrate in a four-stage vertical subsurface flow constructed wetland system to improve phosphorus P removal from domestic wastewater. A 'tidal flow' operation was also employed in the treatment system. Under a hydraulic loading rate (HLR) of 0.76 m3/m2 d for 1st and 3rd stage and HLR of 0.04 m3/m2 d for 2nd and 4th stage of the constructed wetland system respectively and tidal flow operation strategy, average removal efficiencies of 99.4% for P, 95.4% for ammoniacal-nitrogen, 56.5% for total nitrogen and 84.5% for total chemical oxygen demand were achieved during the operation period. The CSW-based constructed wetland system presents excellent P removal performance. The adoption of tidal flow strategy creates the aerobic/anoxic condition intermittently in the treatment system. This can achieve better oxygen transfer and hence lead to more complete nitrification and organic matter removal and enhanced denitrification. Overall, the CSW-based tidal flow constructed wetland system holds great promise for enabling high rate removal of P, ammoniacal-nitrogen and organic matter from domestic wastewater, and transforms CSW from a waste into a useful material.     

Anaerobic co-digestion of sludge with other organic wastes and phosphorus reclamation in wastewater treatment plants for biological nutrients removal.

This paper deals with the performances obtained in full scale anaerobic digesters co-digesting waste activated sludge from biological nutrients removal wastewater treatment plants, together with different types of organic wastes (solid and liquid). Results showed that the biogas production can be increased from 4000 to some 18,000 m3 per month when treating some 3-5 tons per day of organic municipal solid waste together with waste activated sludge. On the other hand, the specific biogas production was improved, passing from 0.3 to 0.5 m3 per kgVS fed the reactor, when treating liquid effluents from cheese factories. The addition of the co-substrates gave minimal increases in the organic loading rate while the hydraulic retention time remained constant. Further, the potentiality of the struvite crystallisation process for treating anaerobic supernatant rich in nitrogen and phosphorus was studied: 80% removal of phosphorus was observed in all the tested conditions. In conclusion, a possible layout is proposed for designing or upgrading wastewater treatment plants for biological nutrients removal process.     

Development of sequencing batch reactor with step feed and recycle.

SBR process shows high nitrogen and phosphorus removal in countries where separated sewers are used. On the other hand, removal efficiency is low in countries where combined sewers are used though the same SBR is applied. This is because the organic concentration (as BOD), which is used as carbon source for denitrification, of combined sewers is much lower than that of separated sewers. Almost all sewers in Korea are combined, and their BOD is low by about 1/2 over the level needed for denitrification. In this study, a SBR process that can optimise organic usage by step feed and recycle is thus developed to increase the removal efficiency of nitrogen and phosphorus, and the results show that the removal rates of BOD, T-N and T-P are 95.4, 81.4 and 86.1%, respectively, though influent BOD is low.     

Post-treatment of a slaughterhouse wastewater: stability of the microbial community of a sequencing batch reactor operated under oxygen limited conditions.

Slaughterhouse wastewater is a complex effluent with an important content of organic nitrogen. After an anaerobic treatment where most of the organic matter is removed, the nitrogen, remains as ammonium and post-treatment of the effluent is necessary. Sequencing batch reactor (SBR) technology has been developed to completely remove nitrogen in one single reactor combining aerobic and anoxic stages. Under oxygen limited conditions only nitrite is produced with concomitant energy saving. The stability and diversity of the microbial community from a nitrifying denitrifying SBR operated under oxygen limited conditions were studied using molecular and respirometric methods. The AOB (ammonia oxidizing bacteria) community was relatively stable Nitrosomonas being the dominant genera although Nitrosospira and Nitrosococcus were detected in low proportions. Nitrite oxidizing bacteria were out competed during the operation under oxygen-limited conditions. After an increase of the DO in the reactor Nitrobacter spp were detected suggesting that they remained in the system. Changes in the AOB and denitrifying communities were observed after the DO increase. Sedimentation problems were detected during operation, this could be related to the predominance of Thauera spp detected by FISH and T-RFLP.     

同步短程硝化反硝化研究

分析了现有短程硝化反硝化工艺处理高浓度氨氮废水所存在的问题,试验利用序批式反应器(SBR)的内部水力特性对其进行改造,以畜禽养殖废水为研究对象,从宏观上创造同步硝化反硝化(SND)条件,并实现了同一反应器内短程硝化反硝化的同步进行,改造后系统pH值下降速度减缓,反硝化效率提高,最终出水的亚硝酸盐和硝酸盐浓度分别降低了39%和38%。     

南方山地丘陵区规模畜禽养殖对水环境影响及评价

选择南方山地丘陵区典型规模畜禽养殖集中地为研究区域,通过对该研究区域周边地表水及地下水的调查采样,分析主要污染物时空变异及污染物形态之间的变化,并对周边水环境进行初步评价。结果表明:规模化畜禽养殖区域的浅层地下水和地表水已经受到严重污染;养殖场的环保处理设施与养殖规模不配套造成大量污染物进入地表水环境;生物氧化塘的护堤和塘底未经防渗处理,造成下游地下水污染;养殖场排放的污水经厌氧和好氧生物处理后富含有机质、氨氮、可溶态有机磷,利于作物吸收和生长,应尽量循环使用。指出由于养殖污水变化较大,为避免二次环境污染,必须处理达标后结合配方施肥技术按需回用农田。     

恒液位SBR工艺处理城市污水的研究

采用恒液位SBR工艺对城市污水处理进行实验研究。研究影响恒液位SBR工艺脱氮除磷效果的缺氧-好氧循环、沉淀时间、进水流量等因素。结果表明:在最佳工况下处理城市污水时,COD、TN、TP和NH3-N去除率分别为88.21%~91.04%、68.04%~70.45%、95.26%~96.11%和89.76%~91.17%,说明采用恒液位SBR工艺处理城市污水是可行的。     

The role of plant uptake on the removal of organic matter and nutrients in subsurface flow constructed wetlands: a simulation study.

Plants in constructed wetlands have several functions related to the treatment processes. It is generally agreed that nutrient uptake is a minor factor in constructed wetlands treating wastewater compared to the loadings applied. For low loaded systems plant uptake can contribute a significant amount to nutrient removal. The contribution of plant uptake is simulated for different qualities of water to be treated using the multi-component reactive transport module CW2D. CW2D is able to describe the biochemical elimination and transformation processes for organic matter, nitrogen and phosphorus in subsurface flow constructed wetlands. The model for plant uptake implemented describes nutrient uptake coupled to water uptake. Literature values are used to calculate potential water and nutrient uptake rates. For a constructed wetland treating municipal wastewater a potential nutrient uptake of about 1.9% of the influent nitrogen and phosphorus load can be expected. For lower loaded systems the potential uptake is significantly higher, e.g. 46% of the nitrogen load for treatment of greywater. The potential uptake rates could only be simulated for high loaded systems i.e. constructed wetlands treating wastewater. For low loaded systems the nutrient concentrations in the liquid phase were too low to simulate the potential uptake rates using the implemented model for plant uptake.     

The potential of nutrient reuse from a source-separated domestic wastewater system in Indonesia--case study: ecological sanitation pilot plant in Surabaya.

Human excreta (faeces and urine) contribute only a small volume in domestic wastewater but are one of the main causes of water pollution. On the other hand, they contain very valuable nutrients to be reused as anthropogenic fertiliser through proper collection, treatment and hygienisation processes. To know the potential of nutrient recovery and reuse in Indonesia, a pilot scale source separation domestic wastewater system has been built in Surabaya and, so far, has shown promising results. Using urine diverting toilets, up to 86% nitrogen, 21% phosphorus and 69% potassium from urine and 12% of nitrogen, 68% of phosphorus and 20% of potassium from the faecal matter can be recovered. The separated urine was stored for 6 months before usage as fertiliser for hygienic reasons, while the separated faecal matter was composted with worms (vermicomposting). In order to investigate the fertilising effect, a preliminary cultivation experiment has been carried out on young rose plants using different fertilisers for 2 months.     

曝气生物滤池降解规律试验研究

采用实际分散型生活污水作为试验原水,对曝气生物滤池的降解规律进行了试验研究。结果表明,与传统的观点不同,曝气生物滤池在处理低浓度有机废水时并不发生严格的有机物与氨氮的分段去除现象,有机废水氨氮与有机质基本在同一区域内去除,滤料在10～40cm段的去除率增长速度最快,在70cm之后去除率的增长开始逐渐变缓。在进口段,由于有机质浓度高,供氧充足,有机质的去除率较高;由于异养菌和氨化菌的作用,氨氮浓度在进口段不但不减少,反有微小升高。     

The performance of a nitrogen-fixing SBR.

A laboratory study has successfully demonstrated that a nitrogen deficient thermomechanical pulping wastewater can be effectively treated in a sequencing batch reactor (SBR) operated under conditions of biological nitrogen fixation (the N-ViroTech process). In comparison to continuous stirred tank reactor activated sludge (CSTR-AS) configurations operated under either nitrogen fixing or nitrogen supplemented conditions, slightly lower removals of dissolved organic material were observed in the SBR. However, this was largely offset by significantly better suspended solids removal in the SBR, which contributes to the overall COD discharge. The settleability and dewaterability of sludge produced by the SBR was significantly better than that obtained from the nitrogen fixing CSTR-AS reactors, and comparable to that of a nitrogen supplemented system. Consistently low total and dissolved nitrogen discharges from the N-ViroTech systems demonstrated the advantage of this system over ones requiring nitrogen supplementation. The feast-famine regime of an SBR-type configuration has significant potential for the application of this technology in the treatment of nitrogen deficient waste streams, particularly those in which conventional single-stage systems may be susceptible to sludge bulking problems.     

循环流环型脱氮除磷工艺处理低浓度城镇污水

结合我国低浓度的城镇污水处理情况,采用循环流环型生物脱氮除磷工艺显示出十分明显的优势.该工艺有效的将活性污泥法和氧化沟工艺结合起来,同时结合了完全混和反应器与循环反应器,优化了反应技术,运行更为稳定,有助于提高系统耐冲击负荷能力,提高处理污水的效率.对比目前较为流形的传统A2/O工艺,可节省能耗达30%以上,同时也能节省工程投资费用,运行管理方便.     

Conditions and technologies of biological wastewater treatment in Hungary

A survey has been carried out involving 55 Hungarian wastewater treatment plants in order to evaluate the wastewater quality, the applied technologies and the resultant problems. Characteristically the treatment temperature is very wide-ranging from less than 10 °C to higher than 26 °C. Influent quality proved to be very variable regarding both the organic matter (typical COD concentration range 600-1,200 mg l(-1)) and the nitrogen content (typical NH(4)-N concentration range 40-80 mg l(-1)). As a consequence, significant differences have been found in the carbon availability for denitrification from site to site. Forty two percent of the influents proved to lack an appropriate carbon source. As a consequence of carbon deficiency as well as technologies designed and/or operated with non-efficient denitrification, rising sludge in the secondary clarifiers typically occurs especially in summer. In case studies, application of intermittent aeration, low DO reactors, biofilters and anammox processes have been evaluated, as different biological nitrogen removal technologies. With low carbon source availability, favoring denitrification over enhanced biological phosphorus removal has led to an improved nitrogen removal.