Reduced order model monitoring and control of a membrane bioreactor system via delayed measurements

Activated sludge treatment is one of the most widely used processes for wastewater treatment (WWT). These systems are built with sufficient design margin to allow changes in loading and process conditions. This is necessary and prudent to overcome limitations in measurement, monitoring and controlling of WWT process parameters at the desired frequency. Online sensors for mixed liquor suspended solids, chemical oxygen demand (COD), nitrogen, phosphorus, and other parameters available today are limited in application due to high cost and low reliability. Hence, many of the parameters are measured off-line when needed. This paper provides a framework to estimate parameters on-line using limited and delayed measurements. The proposed approach is based on the design of a Bayesian filter such as an extended Kalman filter (EKF), which measures and controls membrane bioreactor system using limited and delayed measurements. The objective is to estimate the states and parameters with limited and delayed measurements. Simulations show the efficacy of the proposed approach.     

Construction and analysis of a metagenomic library from an enhanced biological phosphorus removal biomass.

The enhanced biological phosphorus removal (EBPR) process is regularly used for the treatment of wastewater, but suffers from erratic performance. Successful EBPR relies on the growth of bacteria called polyphosphate-accumulating organisms (PAOs), which store phosphorus intracellularly as polyphosphate, thus removing it from wastewater. Metabolic models have been proposed which describe the measured chemical transformations, however genetic evidence is lacking to confirm these hypotheses. The aim of this research was to generate a metagenomic library from biomass enriched in PAOs as determined by phenotypic data and fluorescence in situ hybridisation (FISH) using probes specific for the only described PAO to date, "Candidatus Accumulibacter phosphatis". DNA extraction methods were optimised and two fosmid libraries were constructed which contained 93 million base pairs of metagenomic data. Initial screening of the library for 16S rRNA genes revealed fosmids originating from a range of nonpure-cultured wastewater bacteria. The metagenomic libraries constructed will provide the ability to link phylogenetic and metabolic data for bacteria involved in nutrient removal from wastewater.     

Simultaneous removal of ammonium-nitrogen and sulphate from wastewaters with an anaerobic attached-growth bioreactor.

Some industrial wastewaters may contain ammonium-nitrogen and/or sulphate, which need to be removed before their discharge into natural water bodies to eliminate their severe pollution. In this paper, simultaneous removal of ammonium-nitrogen and sulphate with an anaerobic attached-growth bioreactor of 3.8 L incubated with sulphate reducing bacteria (SRB) was investigated. Artificial wastewater containing sodium sulphate as electron acceptor, ammonium chlorine as electron donor and glucose as carbon source for bacteria growth was used as the feed for the bioreactor. The loading rates of ammonium-nitrogen, sulphate and COD were 2.08 gN/m3 x d, 2.38 gS/m3 x d, 104.17 gCOD/m3 x d, respectively, with a N/S ratio of 1:1.14. The results demonstrated that removal rates of ammonium-nitrogen, sulphate and COD could reach 43.35%, 58.74% and 91.34%, respectively. Meanwhile, sulphur production was observed in effluent as well as molecular nitrogen in biogas, whose amounts increased with time substantially, suggesting the occurrence of simultaneous removal of ammonium-nitrogen and sulphate. This novel reaction provided the possibility to eliminate ammonium-nitrogen and sulphate simultaneously with accomplishment of COD removal from wastewater, making wastewater treatment more economical and sustainable.     

基于NBS的生活污水污染物去除效果研究

NBS与可持续、和谐-绿色发展、资源合理开发和生态保护优先等理念密切相关。在生活污水处理过程中为实现就地取材、成本低、易管理、无二次污染,基于NBS的本地水生植物的合理选取和自然基质的优化组合尤为重要。论文选择5种水生植物(千屈菜、黄菖蒲、芦苇、香蒲、荷花)和6种基质(砂子、石子、炉灰渣、砂子+土、石子+土、炉灰渣+土)进行生活污水的生态处理试验,采用整合分析法研究基质和水生植物对生活污水中的CODMn、TP、TN去除效果,为生活污水的生态处理系统设计提供参考依据。实验结果表明:5种水生植物对CODMn的平均去除率表现为香蒲(85%)芦苇(77%)黄菖蒲(66%)荷花(63%)千屈菜(59%);对TP的平均去除率表现为香蒲(85%)芦苇(76%)黄菖蒲(71%)荷花(69%)千屈菜(61%);对TN平均去除率表现为香蒲芦苇黄菖蒲千屈菜荷花,去除率分别为83%、77%、69%、58%和53%。炉灰渣对生活污水污染物的去除率最高,对CODMn、TN、TP的去除率分别为71%、69%和74%。论文通过评估实验期内同一进水条件下各种组合对污染物的去除能力,确定影响因素,为进行基于NBS的污染物最佳去除效率的研究提供依据。     

生物慢滤池用于污水深度处理的实验研究

利用生物慢滤池对人工模拟污水和西安市某污水处理厂的二级出水进行了深度净化处理实验,通过分析进出水中氮、磷含量和高锰酸盐指数及上层水和出水中的叶绿素a含量等指标,考察了生物慢滤池的净化效果。结果表明:生物慢滤池对人工模拟污水的处理效果较好,总氮、氨氮、总磷和高锰酸盐指数的去除率分别为66.4%、40.2%、66.4%和73.3%;深度净化污水厂二级出水,总氮、氨氮、总磷和高锰酸盐指数的去除率分别为35.1%、21.0%、30.2%和12.6%,去除率略低于人工模拟实验;生物慢滤池对叶绿素a有很好的截留效果,去除率分别为93.4%和66.4%;生物慢滤池处理后的再生水水质达到《城市污水再生利用景观环境用水水质》要求,可回用于城市景观水体,作为城市景观水体的补充水源,避免水体富营养化的发生。     

Estimations of municipal point source pollution in the context of river basin management.

Integrated presentation of total emissions on catchment scale is prerequisite for many tasks in integrated management of point and diffuse sources of pollution. This paper will focus on emissions of nutrients from municipal point sources. Based on calculations of discharges of N, P from households into wastewater and on the detailed evaluation of data from 76 municipal wastewater treatments plants, this paper presents ranges of specific loads of inhabitants and population equivalents in the raw wastewater. In addition data of these treatment plants have been evaluated in respect of the treatment efficiency for nitrogen and phosphorus (average reduction rates) dependent on the design characteristic (with or without nitrification, denitrification or enhanced phosphorus removal). The results of the investigation show that the specific N and P loads from households in Austria lie within the range 1.6-2.0 g P/(inhabitant.d) and 11- 13 g N/(inhabitant.d). The specific contribution of industries to municipal wastewater varies between 0.3 and 2.0 gP/(pe.d) and 0 and 13 g N/(pe.d) with average values of 1.3 g P/(pe.d) and 6.5 g N/(population equivalent (pe)/d). As average values for municipal wastewater (contributions from household and industry) this leads to specific influent loads of 1.5 g P/(pe.d) and 8.8 g N/(pe.d). Average treatment efficiencies of treatment plants are for instance 50% nitrogen removal in treatment plants with nitrification and 80% in treatment plants with nitrification/denitrification. For phosphorus a removal of about 85% can be expected where the treatment plant was designed for enhanced phosphorus removal. Finally a method for load estimations based on standard values as mentioned above was tested for the estimation of emission from municipal point sources of selected regions.     

活性炭吸附技术与树脂吸附技术处理DIBP废水的对比

采用活性炭吸附技术和树脂吸附技术进行增塑剂DIBP生产废水处理对比试验。结果表明:NDA-66树脂对邻苯二甲酸的吸附效果最好,去除率达93.9%,其次为椰壳活性炭,对增塑剂DIBP生产废水中COD和邻苯二甲酸的去除率分别为57.3%和83%,煤质和果壳活性炭的废水处理效果较差,对COD和邻苯二甲酸的去除率均在20%左右,且活性炭吸附不具有选择性,无法对邻苯二甲酸进行回收,不能产生相应的经济效益。而采用NDA-66树脂吸附处理增塑剂DIBP生产废水,其污染物削减量是活性炭吸附的4~5倍,回收邻苯二甲酸可产生110.8万元/a的经济效益,同时树脂脱附再生容易,可重复利用2年左右,因而具有更大的推广应用价值。     

污水灌溉与污水土地处理系统在公厕污水处理中的应用

位于昆明市下游的滇池,因受市区排放的生活污水、工业废水以及当地污水的影响,水污染问题十分突出,急需治理。污水灌溉与污水处理相结合的土地系统是一种可供选择的技术措施。本文阐述了将该系统用于公厕污水处理的工程构造型式与运行管理方式,建立了示范应用工程,开展了污染物去除效果研究和效益分析。结果表明,采用污水灌溉与污水土地处理系统处理公厕污水,处理后回用于厕所冲洗,可获得良好的污水处理效果,并可节约宝贵的淡水资源。该技术在实际应用中具有经济可行性。     

Optimizing sequencing batch reactor (SBR) reactor operation for treatment of dairy wastewater with aerobic granular sludge

The biological wastewater treatment using aerobic granular sludge is a new and very promising method, which is predominantly used in SBR reactors which have higher volumetric conversion rates than methods with flocculent sludge. With suitable reactor operation, flocculent biomass will accumulate into globular aggregates, due to the creation of increased substrate gradients and high shearing power degrees. In the research project described in this paper dairy wastewater with a high particle load was treated with aerobic granular sludge in an SBR reactor. A dynamic mathematical model was developed describing COD and nitrogen removal as well as typical biofilm processes such as diffusion or substrate limitation in greater detail. The calibrated model was excellently able to reproduce the measuring data despite of strongly varying wastewater composition. In this paper scenario calculations with a calibrated biokinetic model were executed to evaluate the effect of different operation strategies for the granular SBR. Modeling results showed that the granules with an average diameter of 2.5 mm had an aerobic layer in between 65-95 microm. Density of the granules was 40 kgVSS/m3. Results revealed amongst others optimal operation conditions for nitrogen removal with oxygen concentrations below 5 gO2/m3. Lower oxygen concentrations led to thinner aerobic but thicker anoxic granular layers with higher nitrate removal efficiencies. Total SBR-cycle times should be in between 360-480 minutes. Reduction of the cycle time from 480 to 360 minutes with a 50% higher throughput resulted in an increase of peak nitrogen effluent concentrations by 40%. Considering biochemical processes the volumetric loading rate for dairy wastewater should be higher than 4.5 kgCOD/(m3*d). Higher COD input load with a COD-based volumetric loading rate of 9.0 kgCOD/(m3*d) nearly led to complete nitrogen removal. Under different operational conditions average nitrification rates up to 5 gNH/(m3*h) and denitrification rates up to 3.7 gNO/(m3*h) were achieved.     

Evaluation of constructed wetlands by wastewater purification ability and greenhouse gas emissions.

Domestic wastewater is a significant source of nitrogen and phosphorus, which cause lake eutrophication. Among the wastewater treatment technologies, constructed wetlands are a promising low-cost means of treating point and diffuse sources of domestic wastewater in rural areas. However, the sustainable operation of constructed wetland treatment systems depends upon a high rate conversion of organic and nitrogenous loading into their metabolic gaseous end products, such as N2O and CH4. In this study, we examined and compared the performance of three typical types of constructed wetlands: Free Water Surface (FWS), Subsurface Flow (SF) and Vertical Flow (VF) wetlands. Pollutant removal efficiency and N2O and CH4 emissions were assessed as measures of performance. We found that the pollutant removal rates and gas emissions measured in the wetlands exhibited clear seasonal changes, and these changes were closely associated with plant growth. VF wetlands exhibited stable removal of organic pollutants and NH3-N throughout the experiment regardless of season and showed great potential for CH4 adsorption. SF wetlands showed preferable T-N removal performance and a lower risk of greenhouse gas emissions than FWS wetlands. Soil oxidation reduction potential (ORP) analysis revealed that water flow structure and plant growth influenced constructed wetland oxygen transfer, and these variations resulted in seasonal changes of ORP distribution inside wetlands that were accompanied by fluctuations in pollutant removal and greenhouse gas emissions.     

Fate of effluent organic matter (EfOM) and natural organic matter (NOM) through riverbank filtration.

Understanding the fate of effluent organic matter (EfOM) and natural organic matter (NOM) through riverbank filtration is essential to assess the impact of wastewater effluent on the post treatment requirements of riverbank filtrates. Furthermore, their fate during drinking water treatment can significantly determine the process design. The objective of this study was to characterise bulk organic matter which consists of EfOM and NOM during riverbank filtration using a suite of innovative analytical tools. Wastewater effluent-derived surface water and surface water were used as source waters in experiments with soil columns. Results showed the preferential removal of non-humic substances (i.e. biopolymers) from wastewater effluent-derived surface water. The bulk organic matter characteristics of wastewater effluent-derived surface water and surface water were similar after 5 m soil passage in laboratory column experiment. Humic-like organic matter in surface water and wastewater effluent-derived surface water persisted through the soil passage. More than 50% of total dissolved organic carbon (DOC) removal with significant reduction of dissolved oxygen (DO) was observed in the top 50 cm of the soil columns for both surface water and wastewater effluent-derived surface water. This was due to biodegradation by soil biomass which was determined by adenosine triphosphate (ATP) concentrations and heterotrophic plate counts. High concentrations of ATP in the first few centimeters of infiltration surface reflect the highest microbial activity which correlates with the extent of DOC reduction. Good correlation of DOC removal with DO and biomass development was observed in the soil columns.     

Quality assessment of an aquifer recharged with wastewater for its potential use as drinking source: "El Mezquital Valley" case.

Mexico City, with a population of 18 million, has been sending its wastewater for more than 100 years to the Tula Valley where it is used to irrigate 90,000 ha. Due to the large wastewater volume (60 m3/s) sent through unlined channels, combined with the use of very high irrigation rates, artificial recharge of the local aquifer has been occurring. This recharge is estimated in more than 25 m3/s. As a consequence, the water table has raised and several springs have appeared in the last decades with flows between 100 to 600 L/s. These springs and several wells are the water sources in the region. An evaluation of the Tula Valley aquifer quality was performed to analyze the use of such water as source of drinking water for Mexico City. The work is divided into 5 individual projects: (a) drinking water quality in the Tula Valley; (b) water availability in the Tula Valley; (c) wastewater treatment due to its use for irrigation, (d) use of membrane processes to treat groundwater; and (d) biota developed in the new surface water reservoirs. Results show that it is feasible to use this reclaimed water as drinking source.     

Treatment of dirty water from dairy farms using a soil-based batch recirculation system.

"Dirty water", a wastewater produced on dairy farms, is typically disposed of by application to land with no prior treatment. Pollution can occur if the dirty water reaches a watercourse following an inadequate period of retention in the soil. This paper describes experiments using a novel, soil-based batch recirculation system for pre-treating dirty water prior to land application. Three polythene-lined, vegetated soil-based treatment planes (23 m long, 1 m wide, 0.25 m deep) were constructed. Each treatment plane was supplied with approximately 1 m3 of dirty water which was recirculated until a clear treatment pattern had emerged. Five batches were treated over a six-month period. The soil-based treatment system could typically be expected to achieve a 90% removal of key pollutants in approximately two weeks for BODs and NH4-N, and three weeks for MRP and total solids. An exponential trendline gave a good fit to the treatment curves for BOD5, NH4-N and MRP after the first day or two of batch treatment. The data for total solids removal were more variable. Treatment rates were sustained throughout the five runs for BOD5 and NH4-N, indicating no apparent effect of seasonal weather on the treatment process. The apparent progressive slowing of the MRP removal rate throughout the treatment of the five batches may have implications for the sustainable use of this technology for phosphorus control.     

Optimal Water Quality Management Considering Spatial and Temporal Variations in a Tidal River

There is an increasing need to establish wastewater treatment facilities for improving water quality of heavily polluted rivers in rapidly urbanizing areas. Optimization models are widely used to determine the pollutant removal levels at different pollution sources, with the aim of minimizing the wastewater treatment cost and satisfying certain water quality criteria. Water quality is usually evaluated in a prescribed space or time point. Thus it cannot reflect the overall status of a tidal river that has significant spatio-temporal variations. In this paper, new spatio-temporal water quality criteria, which consider the water quality violation against specified water quality standards during the whole simulation period of time for the entire river simulated, are proposed and then applied to optimization of a wastewater treatment system in Shenzhen, China. The results indicate that the optimization based on the proposed criteria facilitates an improved performance of wastewater treatment systems in terms of water quality along the whole river during a long time period, instead of just in a prescribed space or time point. Furthermore, use of the new criteria derives a better Pareto front of cost and water quality in terms of convergence and coverage compared with the conventional criteria and thus they are recommended as the water quality criteria to measure spatial and temporal variation in a tidal river for wastewater treatment system planning.     

Estimation and modeling of direct rapid sand filtration for total fecal coliform removal from secondary clarifier effluents

The filtration of fecal coliform from a secondary clarifier effluent was investigated using direct rapid sand filters as tertiary wastewater treatment on a pilot scale. The effect of the flocculation dose, flow loading rate, and grain size on fecal coliform removal was determined. Direct rapid sand filters can remove 0.6-1.5 log-units of fecal coliform, depending on the loading rate and grain size distribution. Meanwhile, the flocculation dose has little effect on coliform removal, and increasing the loading rate and/or grain size decreases the bacteria removal efficiency. A model was then developed for the removal process. Bacteria elimination and inactivation both in the water phase and the sand bed can be described by first-order kinetics. Removal was successfully simulated at different loading rates and grain size distributions and compared with the data obtained using pilot-scale filters.     

景观-生物膜系统在水环境修复中的应用分析

景观-生物膜系统是一种新型废水、污水处理系统,对于水环境的修复具有重要作用。本文对美人蕉、鸢尾及海寿3种植物在景观-生物膜系统中的应用效果进行了对比分析,结果表明:在相同水质情况下,美人蕉的生长状况优于其他两种植物;美人蕉的生物量随运行时间呈"适应生长、快速生长、缓慢生长"三阶段变化特征,而鸢尾和海寿则呈"快速增加、缓慢增加"两阶段变化特征;三种植物对于TN、TP去除均有较好效果,并随时间呈幂函数降低;美人蕉、鸢尾及海寿对于TN的去除率分别为59.4%、50.0%和47.8%,对于TP的去除率分别为54.3%、45.7%和37.1%;植物吸收并不是影响元素去除的唯一因素,美人蕉相较于鸢尾及海寿,具有去除效率高、见效快等优势。     

Urban Water Management in Developing Arid Countries

Urbanization, industrialization and rapid population growth in developing countries of the Arabian Peninsula are putting increasing pressure on local water authorities and water planners to satisfy the growing urban water and sanitation demands. In the Arabian Peninsula, water resources are limited, average rainfall is low and the seawater and brackish water desalination in addition to limited groundwater resources are the major water supply sources. The population increased from about 17.688 million in 1970 to 38.52 million in 1995 and is expected to reach 81.25 million in 2025. The urban population is expected to rise from 60% in 1995 to more than 80% in 2025. The domestic water demand is expected to rise from 2863 million cubic metres (MCM) in 1990 to about 4264 MCM in 2000 and 10580 MCM in 2025. In Saudi Arabia, the population increased by 143.6% between 1970 and 1995; and it is expected to reach about 40.426 million in 2025, with about 80% urban population. The domestic water demand in the Kingdom is expected to be about 2350 MCM in 2000 and 6450 MCM in 2025. Specialized agencies have been established for water production and distribution, and for wastewater collection, treatment and reuse. Special legislation has been introduced to manage water demands and to protect the interests of the community and its natural resources. Fifty-seven costly desalination plants have been constructed in the Peninsula on the Gulf and Red Sea coasts, as well as water transmission lines to transport the desalinated water to coastal and inland major cities. The seawater desalination unit cost is about US$0.70/m 3 for a large desalination plant with energy priced at world prices. More than $30 billion has been invested on water and sanitation projects. Present desalination production is about 46% of the total domestic demand, and the rest is pumped from deep and shallow aquifers. In general, fragmented legislation and institutional arrangements and low water charges have indirectly resulted in over-usage of domestic water, production of excessive quantities of wastewater, significant leakage, and enhancement of shallow water-table formation and rise in some cities. Facing the challenges of satisfying the growing urban water demands requires several essential measures such as: (a) introduction of new technologies to reduce water demands, and losses, and to enhance wastewater recycling and water conservation; (b) the updating of legislation to coordinate both responsibilities and actions among different water agencies; (c) the introduction of a strong and transparent regulatory framework to adopt different forms of water supply privatization, to reduce the costs of building, operation and maintenance of water and sanitation facilities, and to improve the level of services and billing, leakage and wastewater collection and treatment; (d) an increase in water tariffs to reflect the actual value of the water, and to enhance the awareness of public as to the value of water; and (e) development of short-term and long-term national water plans based on realistic water demand forecasting.     

膜分离技术处理淀粉污水试验研究

针对传统污水处理方法中蛋白质去除率较低而COD负荷增加问题,采用膜处理装置进行试验研究。在膜分离技术的基础上,以调节豆浆废水、淀粉废水等电位点作为预处理,采用中空纤维膜装置进行超过滤,并对温度影响作定性分析。结果表明,膜分离技术可以大大提高这两种废水中COD的去除率,分别为76.3%和82.9%;去除率与膜组件的孔径有密切关系;另外,适当的温度可以提高污水处理的效率,试验得出20℃时效率最佳;淀粉等废水处理后的蛋白质还可以作为肥料被充分利用。     

Constructed wetland as a low cost and sustainable solution for wastewater treatment adapted to rural settlements: the Chorfech wastewater treatment pilot plant

The paper presents the detailed design and some preliminary results obtained from a study regarding a wastewater treatment pilot plant (WWTPP), serving as a multistage constructed wetland (CW) located at the rural settlement of 'Chorfech 24' (Tunisia). The WWTPP implemented at Chorfech 24 is mainly designed as a demonstration of sustainable water management solutions (low-cost wastewater treatment), in order to prove the efficiency of these solutions working under real Tunisian conditions and ultimately allow the further spreading of the demonstrated techniques. The pilot activity also aims to help gain experience with the implemented techniques and to improve them when necessary to be recommended for wide application in rural settlements in Tunisia and similar situations worldwide. The selected WWTPP at Chorfech 24 (rural settlement of 50 houses counting 350 inhabitants) consists of one Imhoff tank for pre-treatment, and three stages in series: as first stage a horizontal subsurface flow CW system, as second stage a subsurface vertical flow CW system, and a third horizontal flow CW. The sludge of the Imhoff tank is treated in a sludge composting bed. The performances of the different components as well as the whole treatment system were presented based on 3 months monitoring. The results shown in this paper are related to carbon, nitrogen and phosphorus removal as well as to reduction of micro-organisms. The mean overall removal rates of the Chorfech WWTPP during the monitored period have been, respectively, equal to 97% for total suspended solids and biochemical oxygen demand (BOD5), 95% for chemical oxygen demand, 71% for total nitrogen and 82% for P-PO4. The removal of E. coli by the whole system is 2.5 log units.     

Treatment of non-biodegradable cutting oil wastewater by ultrasonication-Fenton oxidation process.

To treat cutting oil wastewater produced in metal surface treatment industry, Ultrasonication (US)-Fenton process, which is one of the advanced oxidation processes, was used. The optimum conditions to treat non-biodegradable pollutants using the US-Fenton process were that the application rates of H2O2 and FeSO4 were 10% and 3 g/L, respectively, the value of pH was 3, and the ultrasonication time was 30 min. It identified non-degradable pollutants such as ethylene diamine tetraacetic acid (EDTA) and Triethanolamine (TEA) in the cutting oil wastewater. TLC analysis of two compounds of treated water by the coagulation process was similar to that of raw water. However, TLC analysis of two compounds of US-Fenton process was different from that of raw water, meaning that US-Fenton process decomposed the EDTA and TEA. To study the possibility of application with the US-Fenton process to pilot plant, the pollutants treatment efficiency of three different methods, such as US-Fenton process, activated sludge process and coagulation process, in continuous experiments were compared. The removal rate of pollutants by the US-Fenton process according to the effluent time was higher than any other processes. The removal rates of COD, SS, T-N and T-P by US-Fenton process were 98, 93, 75 and 95%, respectively.