Occurrence of levofloxacin, clarithromycin and azithromycin in wastewater treatment plant in Japan.

Residual pharmaceutical products in sewage and other water environments have recently become a serious social problem in advanced countries. Among these pharmaceutical products, antibiotics have attracted special attention due to their serious impact on the ecosystem and connections to the emergence of drug-resistant bacteria. Our research intended to develop a new method to analyse the three antibiotics estimated to be released out of the body in large amounts in Japan; levofloxacin (LVFX), clarithromycin (CAM) and azithromycin (AZM), and survey the state of pollution in the sewerage. The concentrations of the water-phase antibiotics LVFX, CAM and AZM were measured in each process of activated sludge process in six wastewater treatment plants. Liquid chromatography tandem mass spectrometry (LC/MS/MS) was used to analyse solutions of the antibiotics after pretreatment with a solid phase extraction. The limits of quantification and the average recoveries for these antibiotics in the influent were 1.2 to 29 ng/L and 46 to 93%, respectively. In the influent, LVFX, CAM and AZM were detected at concentrations of 552, 647 and 260 ng/L, respectively, while their removal efficiencies were 42, 43 and 49%, respectively. Although the CAM and AZM concentrations decreased as the treatment progressed, it was shown that the LVFX concentration increased in activated sludge reactors in some cases. Despite differences in octanol-water partition coefficients among LVFX, CAM and AZM, their removal efficiency showed no major difference. This indicates that this removal phenomenon cannot be explained by simple adsorption by the activated sludge.     

Mosquito development and biological control in a macrophyte-based wastewater treatment plant.

A one-year study of the proliferation of mosquito in a Pistia stratiotes-based waste stabilization ponds in Cameroon revealed that Mansonia and Culex were the main breeding genera with about 55% and 42% of the total imagoes respectively. Though the ponds represent a favorable breeding ground for mosquitoes, only 0.02% of captured imagoes was Anopheles gambiae, suggesting that this wastewater treatment plant does not significantly contribute to the development of the malaria vector in the area. Gambusia sp. introduced to control mosquito population in the ponds acclimatized relatively well in most of the ponds (B3-B7) and their feeding rate without any diet ranged from 15.0 to 50.2 larvae/day for a single fish.     

Model-based evaluation of nitrogen removal in a tannery wastewater treatment plant.

Computer modelling has been used in the last 15 years as a powerful tool for understanding the behaviour of activated sludge wastewater treatment systems. However, computer models are mainly applied for domestic wastewater treatment plants (WWTPs). Application of these types of models to industrial wastewater treatment plants requires a different model structure and an accurate estimation of the kinetics and stoichiometry of the model parameters, which may be different from the ones used for domestic wastewater. Most of these parameters are strongly dependent on the wastewater composition. In this study a modified version of the activated sludge model No. 1 (ASM 1) was used to describe a tannery WWTP. Several biological tests and complementary physical-chemical analyses were performed to characterise the wastewater and sludge composition in the context of activated sludge modelling. The proposed model was calibrated under steady-state conditions and validated under dynamic flow conditions. The model was successfully used to obtain insight into the existing plant performance, possible extension and options for process optimisation. The model illustrated the potential capacity of the plant to achieve full denitrification and to handle a higher hydraulic load. Moreover, the use of a mathematical model as an effective tool in decision making was demonstrated.     

Stability analysis of a wastewater treatment plant with saturated control.

This paper presents a saturated proportional controller that achieves depollution of wastewater in a continuous anaerobic digester. This goal is reached by defining a region of the state-space where the depollution is achieved and forcing attractivity and invariance of this region. The control variable is the dilution rate and the controlled variable is a linear combination (S(lambda)) of the substrates concentrations, that could be the chemical oxygen demand or the biological oxygen demand, depending on the value of A. No measurement of the substrates concentrations in the input flow is required: the only necessary measurement is S(lambda).     

Modeling of a large-scale wastewater treatment plant for efficient operation.

Environmental legislations in the Western world impose stringent effluent quality standards for ultimate protection of the environment. This is also observed in Turkey. The current paper presents efforts made to simulate an existing 0.77 million m3/day conventional activated sludge plant located at Ankara, AWTP. The ASM1 model was used for simulation in this study. The model contains numerous stoichiometric and kinetic parameters, some of which need to be determined on case by case bases. The easily degradable COD (S(S)) was determined by two methods, physical-chemical and respirometric methods, namely. The latter method was deemed unreliable and rejected in the further study. Dynamic simulation with SSSP program predicted effluent COD and MLSS values successfully while overestimating OUR. A complete fit could only be obtained by introducing a dimensionless correction factor (etaO2 = 0.58) to the oxygen term in ASM1.     

Performance intensification of Prague wastewater treatment plant.

Prague wastewater treatment plant was intensified during 1994--1997 by construction of new regeneration tank and four new secondary settling tanks. Nevertheless, more stringent effluent limits and operational problems gave rise to necessity for further intensification and optimisation of plant performance. This paper describes principal operational problems of the plant and shows solutions and achieved results that have lead to plant performance stabilisation. The following items are discussed: low nitrification capacity, nitrification bioaugmentation, activated sludge bulking, insufficient sludge disposal capacity, chemical precipitation of raw wastewater, simultaneous precipitation, sludge chlorination, installation of denitrification zones, sludge rising in secondary settling tanks due to denitrification, dosage of cationic polymeric organic flocculant to secondary settling tanks, thermophilic operation of digestors, surplus activated sludge pre-thickening, mathematical modelling.     

Membrane separation of indigenous noroviruses from sewage sludge and treated wastewater.

In this study, feasibility of membrane separation for the removal of indigenous noroviruses (NVs) is evaluated. The indigenous NV gene was never detected from ultrafiltration (UF) permeates of sewage sludge and treated wastewater. Indigenous NV gene was also not detected from permeates of sewage sludge and treated wastewater by microfiltration (MF) with a pore size of 0.1 microm (MF0.1). Even though the pore size of MF (0.1 microm) was much larger than the diameter of virus particle (approximately 30-40nm), more than 4-log10 reduction value (LRV) at maximum was achieved by membrane separation with MF0.1. NV genes were often detected from permeates of sewage sludge and treated wastewater by MF with a pore size of 0.45 microm (MF0.45), although the maximum log10 reduction values were more than 3.59 for sewage sludge and more than 2.90 for treated wastewater. It is important to verify factors determining the removal efficiency of viruses with MF membranes.     

Improvement of wastewater treatment performance of the Fukashiba treatment plant.

The Fukashiba Treatment Plant Kashima Rinkai Specified Sewage Works has received wastewater from the petrochemical complex (90%) and public sewage of Kamisu and Hasaki town (10%). For this reason, the plant is facing many difficulties in producing good quality effluent. In order to solve these difficulties, we are reviewing the treatment performance and making efforts for its improvement with nitrification inhibition, control of bio-persistent substances and the PRTR approach.     

Disinfection of sludge using lime stabilisation and pasteurisation in a small wastewater treatment plant.

Removal efficiency of faecal coliforms and helminth eggs was evaluated in a small wastewater treatment plant (WWTP) serving a population of 1,000. This system was formed by the association in series of a UASB reactor and four submerged aerated biofilters. The density of faecal coliforms and the count of helminth eggs were estimated in the liquid and solid phases of the system. Two different methods of disinfecting sludge were investigated: (a) chemical treatment with lime and (b) a physical treatment by pasteurisation. As expected, the association UASB + BF was very efficient at removal of helminth eggs from the final tertiary effluent, but coliforms were still present at high densities. Lime treatment and pasteurisation of sludge were very effective methods of disinfection and produced a sludge safe for final disposal.     

MBR pilot plant for textile wastewater treatment and reuse.

An experimental study was carried out in order to evaluate the possibility of upgrading the conventional activated sludge WWTP of Seano (Prato, Italy) which treats municipal and textile wastewaters, by using membrane bioreactor (MBR) technology. The MBR pilot plant, set up within Seano WWTP, was fed with mixed municipal-industrial wastewaters during the first experimental period and with pure industrial wastewaters during the second. Performances and operation of the MBR were evaluated in terms of permeate characteristics and variability (COD, colour, surfactants, total N and P) and other operational parameters (sludge growth and observed yield). According to the experimental results the MBR permeate quality was always superior to the Seano WWTP one and it was suitable for industrial reuse in the textile district of the Prato area. Respirometric tests provided a modified IWA ASM1 model which fits very well the experimental data and can be used for the design and the monitoring of a full-scale MBR pilot plant.     

Substrate utilization characteristics of the predominant filamentous and floc-forming bacteria isolated from a chemical fiber factory wastewater treatment plant

To supply theoretical verification of the function of a selector to control aerobic activated sludge bulking in the wastewater treatment plant for a chemical fiber factory in Taiwan, the filamentous and floc-forming bacteria in the aeration tank in the full-scale plant were examined microscopically and isolated. The kinetic characteristics of filamentous and floc-forming bacteria were also investigated.The predominant filamentous organism was Sphaerotilus natans. In addition to this organism, 21 strains of non-filamentous bacteria were isolated using the plate count method. These included Aeromonas jandaei DNA group 9, Acinetobacter johnsonii/genospecies 7, Bacillus pasteurii and Bacillus sp. (using the Biolog identification system). Nine strains showed the ability to form flocs when cultivated in glucose mineral salts medium.With glucose and acetate as sole substrates, the 4 floc-forming bacteria tested showed different substrate utilization characteristics. The 4 strains could be divided into 3 groups. The first group was the substrate degrading bacteria, the second group was the acid degrading bacteria and the other strains were those that had the highest substrate degradation rates at low substrate concentrations (below 800 mg/l). None of the floc-formers could utilize ethylene glycol, which is the major wastewater component. The kinetic characteristics of filamentous bacterium S. natans (Km = 4.0 mg glucose/l, Vm = 0.43 μl O₂/l) and the flocforming bacterium Aeromonas jandaei DNA group 9 (Km = 34.8 mg glucose/l, Vm = 0.59 μl O₂/l) provided information for selector design.     

日本污水处理厂设计运行及多因素影响分析

日本的污水处理起步较早,经过多年发展已经建设完善,并在其精细管理下编撰为《下水道統計》.对日本污水处理和污泥处置情况进行全面统计和深入分析,期望对我国污水处理厂的建设和运行具有借鉴意义.污水处理环节分析包括水质水量、处理要求、工艺和处理规模分布、深度处理方法、运行和设计参数、出水回用等;污泥处理环节分析包括污泥产量、处...     

Seasonal variation of fecal indicator bacteria in storm events within the US stormwater database

Bacteria are one of the major causes of surface water impairments in the USA. Over the past several years, best management practices, including detention basins, manufactured devices, grass swales, filters and bioretention cells have been used to remove bacteria and other pollutants from stormwater runoff. However, there are data gaps in the comprehensive studies of bacteria concentrations in stormwater runoff. In this paper, the event mean concentration (EMC) of fecal indicator bacteria (Enterococcus, Escherichia coli, fecal Streptococcus group bacteria, and fecal coliform) across the USA was retrieved from the international stormwater best management practices database to analyze the seasonal variations of inflow and outflow event mean concentrations and removal efficiencies. The Kruskal-Wallis test was employed to determine the seasonal variations of bacteria indicator concentrations and removals, and the two-sample Kolmogorov-Smirnov test was used for comparing different seasonal outcomes. The results indicate that all the inflow EMC of FIB in stormwater runoff is above the water quality criteria. The seasonal differences of fecal Streptococcus group bacteria and fecal coliform are significant. Summer has the potential to increase the bacteria EMC and illustrate the seasonal differences.     

Selection of an ultraviolet disinfection system for a municipal wastewater treatment plant.

As part of an expansion to an average flow of 45.9 million gallons per day (174 mld), the Ypsilanti Community Utilities Authority wastewater treatment plant in the State of Michigan, USA, elected to install ultraviolet disinfection as a replacement for the existing chlorination process. This paper presents a unique methodology used in selecting the best system based on not only the life cycle costs, and O & M considerations but also the participation of the stakeholders. The Team members consisted of representatives of all departments at the Authority, and these Team members made the decision. The Team evaluated all criteria in the office, which was followed by verification at selected sites with similar types of equipment. The selected equipment then was pilot tested for validation of the dose-kill relationship under normal operation and also under reduced irradiation conditions. A low-pressure, high intensity system was selected, based on life-cycle cost, reliability, safety, and ease of operation. This paper describes the unique methodologies used in making that decision. The full-scale system is scheduled for start-up in Spring 2003.     

Removal efficiency of 66 pharmaceuticals during wastewater treatment process in Japan.

Both biological treatment processes including conventional activated sludge (CAS) and biological nutrient removal (BNR) processes, and physico-chemical treatment processes including ozonation process and Title 22 process consisting of coagulation, sedimentation and filtration followed by UV or chlorination disinfection after the above biological processes, were compared from the viewpoint of removal efficiency. 66 pharmaceuticals including antibiotics, analgesics, psychoneurotic agents were measured with SPE-LC/MS/MS. 26 compounds out of 66 were detected in the influent ranging ng/L to microg/L order. Particularly, disopyramide, sulpiride, and dipyridamole that have been rarely detected before in the WWTP, occurred at concentration levels of more than 100 ng/L. The total concentration of the individual pharmaceuticals in the influent was efficiently removed by 80% during the biological treatment. But removal efficiencies of carbamazepine and crotamiton were less than 30%. The total concentration of the individual pharmaceuticals in the effluent from CAS process was 1.5 times higher than that from BNR process. Further, the total concentration of the individual pharmaceuticals in the discharge from WWTPs applying ozonation following activated sludge process was reduced to less than 20%. Physico-chemical treatment train called Title 22 treatment after CAS could not efficiently remove the pharmaceuticals. However, ozonation process followed by biological activated carbon process could efficiently reduce all the residual pharmaceuticals below their quantification limits.     

Ecophysiology and niche differentiation of Nitrospira-like bacteria, the key nitrite oxidizers in wastewater treatment plants.

Nitrite-oxidizing bacteria of the genus Nitrospira are key nitrifiers in wastewater treatment plants. Pure cultures of these organisms are unavailable, but cultivation-independent molecular methods make it possible to detect Nitrospira-like bacteria in environmental samples and to investigate their ecophysiology. Comprehensive screening of natural and engineered habitats and of public databases for 16S rRNA sequences of Nitrospira-like bacteria revealed a surprisingly high biodiversity in the genus Nitrospira, which comprises at least four phylogenetic sublineages. All Nitrospira-like bacteria detected in wastewater treatment plants belonged to the sublineages I and II. Subsequently, the population dynamics of different Nitrospira-like bacteria were monitored, by quantitative fluorescence in situ hybridization with rRNA-targeted probes, confocal laser scanning microscopy and digital image analysis, during incubation of nitrifying activated sludge in media containing different nitrite concentrations. These experiments showed that Nitrospira-like bacteria, which were affiliated with the phylogenetic sublineages I or II of the genus Nitrospira, responded differently to nitrite concentration shifts. Previously unknown properties of Nitrospira-like bacteria were discovered in the course of an environmental genomics project. Implications of the obtained results for fundamental understanding of the microbial ecology of nitrite oxidizers as well as for future improvement of nutrient removal in wastewater treatment plants are discussed.     

日本东京城市排水资源的有效利用

城市排水资源是都市宝贵的财富。东京城市排水不仅给城市建设、居民生活提供了可靠的资源和方便 ,而且美化了人们的生活环境。介绍了日本东京城市排水、污泥、能源及排水设施有效利用的技术和方法 ,为我国城市走可持续性发展提供了借鉴经验     

Use of modelling for optimization and upgrade of a tropical wastewater treatment plant in a developing country.

This paper presents results of a novel application of coupling the Activated Sludge Model No. 3 (ASM3) and the Anaerobic Digestion Model No.1 (ADM1) to assess a tropical wastewater treatment plant in a developing country (Surat, India). In general, the coupled model was very capable of predicting current plant operation. The model proved to be a useful tool in investigating various scenarios for optimising treatment performance under present conditions and examination of upgrade options to meet stricter and upcoming effluent discharge criteria regarding N removal. It appears that use of plant-wide modelling of wastewater treatment plants is a promising approach towards addressing often complex interactions within the plant itself. It can also create an enabling environment for the implementations of the novel side processes for treatment of nutrient-rich, side-streams (reject water) from sludge treatment.     

Comparison of the behaviour of selected micropollutants in a membrane bioreactor and a conventional wastewater treatment plant.

Micropollutants as pharmaceutical active compounds (PhACs), residuals of personal care products or endocrine disrupting chemicals are of increasing interest in water pollution control. In this context the removal efficiencies of sewage treatment plants (STPs) are of importance, as their effluents are important point sources for the release of those substances into the aquatic environment. Activated sludge based wastewater treatment is the worldwide prevalently used treatment technique. In conventional plants the separation of treated wastewater and sludge occurs via sedimentation. A new development is the application of membrane technology for this separation step. The studies focus on the influence of the solids retention time (SRT) on the removal efficiency, as the SRT is the most important parameter in the design of STPs. A conventional activated sludge plant (CASP) and a membrane bioreactor (MBR) were operated at different SRTs. The substances selected are the antiepileptic carbamazepine, the analgesics diclofenac and ibuprofen, the lipid regulator bezafibrate, the polycyclic musks tonalide and galaxolide and the contraceptive 17alpha-ethinylestradiole. No significant differences in the removal efficiency were detected. Due to the absence of suspended solids in the MBR effluent, substances with high adsorption potential could be retained to slightly higher amounts.     

301医院污水处理二期工程工艺过程监测与自动控制

简要介绍了301医院污水处理站二期工程自动控制系统的设计与实施方案,对采用典型“调节—好氧—沉淀—消毒”工艺的医院污水处理设备、过程监测对象的特点及采取的自动控制逻辑进行了分析,并就运行中出现的一些问题及对策进行了讨论。