采用淡水发光菌评估污水处理厂进出水毒性的研究

采用淡水发光菌Q67对某地区7座污水处理厂的进出水进行了急性毒性检验,同时结合化学需氧量(CODCr)、五日生化需氧量(BOD5)和悬浮物(SS)对水质进行了综合评估。总进水和二沉池出水对发光菌的抑光率分别为39%～72%和1%～23%,结果表明总进水经处理后毒性显著下降;总进水的有效浓度(EC30)与BOD5、CODCr和SS正相关(P0.05),但二沉池出水不相关(P0.05)。毒性指标和化学指标并非在任何水体中都相关,但发光菌试验仍是化学分析的有效补充。     

Tertiary filtration in small wastewater treatment plants.

Tertiary filtration can be proposed in small wastewater treatment plants with impact on protected water bodies. Rotating disk filters may be adopted, in respect to conventional sand filters, when low availability of space and low investment costs are the prevailing conditions. The overall objective of this research was to evaluate the filtration efficiency of rotating disk filters; to compare effectiveness with traditional sand filters; to analyse thoroughly the importance of particle size distribution in wastewater tertiary filtration. In the experimental activity, conventional wastewater quality parameters were investigated and particle size distribution (PSD) was characterized to discuss the filter effectiveness. The effect of design and operation parameters of tertiary filters were discussed related to particle removal curves derived from particles counts. Analysis of particle size distribution can be very useful to help comprehension of filtration processes, design of filtration treatments and to decide the best measures to improve filter performance.     

Computational intelligence-based optimisation of wastewater treatment plants.

Methods of computational intelligence (CI), especially fuzzy control and neuronal networks, are used for controlling and optimising of wastewater treatment plants. Areas of application are the control of sludge water dosage, of phosphate elimination by optimal precipitant dosage as well as an optimal aeration in the nitrification zone. In two municipal wastewater treatment plants with 60,000 and 12,600 person equivalents the controllers have been installed and optimised and they have been in operation for several years. Results of operation of the plants are presented in comparison to previously used classical control. Performance increased significantly and the outflow values could be kept securely below the government requirements without increase of the energy consumption. Peak loads in the inflow were eliminated in the plant and did not increase outflow concentrations. Results of operation for more than three years clearly show that the CI controller is a cost-efficient method for a sustainable rise of performance in municipal wastewater treatment plants.     

Steroid estrogens in primary and tertiary wastewater treatment plants.

The concentrations of two natural estrogens (estrone (E1) and Estradiol (E2)) and one synthetic progestin (Ethinylestradiol (EE2)) were measured for different unit operations in an advanced sewage treatment plant and in a large coastal enhanced primary sewage treatment plant. The average influent concentration to both plants was similar: 55 and 53 ng/L for E1 and 22 and 12 ng/L for E2 for the advanced and enhanced primary STPs, respectively. The activated sludge process at the advanced STP removed up to 85% and 96% of E1 and E2, respectively. The enhanced primary sewage treatment plant was mostly ineffective at removing the steroids with only 14% of E1 and 5% of E2 being removed during the treatment process. EE2 was not been detected during the study period in the influent or effluent of either STP. The difference in the observed removal between the two plants is primarily linked to plant performance but the extent to which removal of steroid estrogens is due to bacterial metabolism (i.e. the advanced STP) rather than adsorption to the bacterial biomass remains unclear. The poor removal observed for the coastal enhanced primary STP may have implications for the receiving environment in terms of a greater potential for abnormal reproductive systems in marine animals, particularly if discharges are into large bays or harbours where flushing is limited.     

Semi-intensive treatment plants for wastewater reuse in irrigation.

Semi-intensive technologies are a middle term between intensive ones (e.g., activated sludge with a retention time of hours) and extensive ones (e.g., stabilization ponds with a retention time of several weeks). The most common semi-intensive configuration used in Israel is made of anaerobic ponds followed by aerated lagoons. These small low-energy units remove about 75-80% of the BOD and are followed by wastewater reservoirs for storage and complementary treatment. The reduction in loading allows a flexible operation of the reservoirs for the removal of other pollutants, while providing storage capacity to cope with the changes in water demand for irrigation during the year. In schemes for wastewater reuse in irrigation, this lay-out has proved to be low-cost, low-energy, flexible, reliable and efficient. Variations of this basic configuration are the use of UASB reactors instead of anaerobic ponds, aerated lagoons in series or low-rate trickling filters instead of aerated lagoons, constructed wetlands or rock-filters for algae removal, etc. Semi-intensive technologies use less energy than intensive ones, and less land than extensive ones. They can remove as much BOD as intensive ones, and as much pathogens and refractory pollutants as extensive ones. They release no or very small amounts of sludge.     

The effect of public or private structures in wastewater treatment on the conditions for the design, construction and operation of wastewater treatment plants.

Organised in public or private structures, wastewater services have to cope with different framework conditions as regards planning, construction, financing and operation. This leads quite often to different modes of management. In recent years there has been a push for privatisation on the water sector in general, the reasons for which are manifold, ranging from access to external know-how and capital to synergistic effects through integration of wastewater treatment into other tasks of similar or equal nature. Discussed are various models of public/private partnership (PPP) in wastewater treatment, encompassing for example the delegation of partial tasks or even the proportional or entire transfer of ownership of treatment facilities to private third parties. Decisive for high performance and efficiency is not the legal or organisational form, but rather the clear and unmistakable definition of tasks which are to be assigned to the different parties, customers and all other partners involved, as well as of clear-cut interfaces. On account of the (of course legitimate) profit-oriented perspective of the private sector, some decision-making processes in relation to project implementation (design and construction) and to operational aspects will differ from those typically found on the public sector. This does apply to decisions on investments, financing and on technical solutions too. On the other hand, core competencies in wastewater treatment should not be outsourced, but remain the public bodies' responsibility, even with 'far-reaching' privatisation models. Such core competencies are all efforts geared to sustainable wastewater treatment as life-supporting provision for the future or as contribution to the protection of health and the environment and to the development of infrastructure. Major areas of wastewater treatment and other related tasks are reviewed. The paper concludes with a list of questions on the issue of outsourcing.     

Performances of three R-AN-D-N wastewater treatment plants in the Czech Republic.

The evolution of Czech standards requires higher efficiency of nutrient removal from municipal wastewaters. At the beginning of the last decade of 20th century, a new activated sludge configuration called R-AN-D-N process has been described, successfully tested and now largely used at several wastewater treatment plants (WWTP) in the Czech republic. The main feature of the R-AN-D-N process is the introduction of a regeneration zone in sludge recycle, which enables to increase sludge age in the system without any substantial increase in WWTP volume. Performances of three Czech large WWTP with R-AN-D-N configuration have been monitored and compared within a period of one and a half years. The results confirmed excellent nutrient removal efficiency for wastewaters with different proportion between sewage and industrial effluents. Two of three monitored WWTP received wastewaters from breweries (Budweiser and Pilsner Urquell). The settleability of activated sludge from all three WWTP was correct, with SVI values usually ranging from 50 to 150 ml/g. Monitoring of sludge composition indicated proliferation of several filamentous bacteria, particularly types 0581, 0092 and M. parvicella. No severe bulking events were observed. Finally, the operational costs expressed in CZK (Czech crown: 1 CZK = [see symbol in text]0.0322) per cubic metre of treated sewage or per capita amounts respectively from 2.24 to 6.52, and from 285 to 342.     

Fault detection for control of wastewater treatment plants.

Interest in real-time model-based control is increasing as more and more facilities are being asked to meet stricter effluent requirements while at the same time minimizing costs. It has been identified that biological process models and automated process control technologies are being used at wastewater treatments plants throughout the world and that great potential for optimising biotreatment may exist with the integration of these two technology areas. According to our experience, wastewater treatment plants are indeed looking for ways to successfully integrate their modelling knowledge into their process control structure; however, there are practical aspects of this integration that must be addressed if the benefits of this integration are to be realised. This paper discusses the practical aspects of monitoring, filtering and analysing real sensor data with an aim to produce a reliable real-time data stream that might be used within a model-based control structure. Several real case study examples are briefly discussed in this paper.     

德国污水处理厂水质状况介绍

介绍了2004年德国污水处理厂数量和规模情况,以及污水处理厂的进出水水质状况,出水水质等级划分标准和实际污染物排放的统计结果。为我国降低污染物排放浓度,提高污水处理效率提供参考。     

Dynamic monitoring system for full-scale wastewater treatment plants.

This paper proposes a new process monitoring method using dynamic independent component analysis (ICA), ICA is a recently developed technique to extract the hidden factors that underlie sets of measurements, whereas principal component analysis (PCA) is a dimensionality reduction technique in terms of capturing the variance of the data. Its goal is to find a linear representation of non-Gaussian data so that the components are statistically independent. PCA aims at finding PCs that are uncorrelated and are linear combinations of the observed variables, while ICA is designed to separate the ICs that are independent and constitute the observed variables. The dynamic ICA monitoring method is applying ICA to the augmenting matrix with time-lagged variables. The dynamic monitoring method was applied to detect and monitor disturbances in a full-scale biological wastewater treatment (WWTP), which is characterized by a variety of dynamic and non-Gaussian characteristics. The dynamic ICA method showed more powerful monitoring performance on a WWTP application than the dynamic PCA method since it can extract source signals which are independent of time and cross-correlation of variables.     

Biosensor-based control of nitrification inhibitor in municipal wastewater treatment plants.

The effect of potassium cyanide (KCN) on nitrification processes in municipal wastewater treatment plants was studied by batch nitrification tests, which indicated that nitrification processes tend to be inhibited at a lower KCN concentration than the present discharge standard to sewerage. The experiment of the biosensor using nitrifying bacteria was also conducted for continuous monitoring of nitrification inhibitor in influent wastewater, and demonstrated that the biosensor can detect KCN at as low as EC10 of the abovementioned batch nitrification test. Moreover, to determine the effectiveness of application of the biosensor to avoid the impact of KCN due to an accidental spillage in a sewerage system, KCN was intentionally injected into the experimental models of activated sludge process equipped both with and without the biosensor. The model with the biosensor that could detect KCN could divert the wastewater including KCN to a refuge tank, which resulted in the avoidance of upset of the activated sludge process. On the other hand, the model without the biosensor was upset in the nitrification process due to KCN. Such differences demonstrate the effectiveness of the biosensor applied to countermeasures of an accidental spillage of toxic chemicals to avoid upset of nitrification in municipal wastewater treatment plants.     

A guideline for simulation studies of wastewater treatment plants.

A guideline for simulation studies of wastewater treatment plants is proposed. The aim of the HSG-guideline is to define a reference quality level that helps to make the results of simulation studies comprehensible and comparable and therefore increases the quality and reliability of mathematical modelling in wastewater treatment. The paper gives a summary of the HSG-guideline, written by a group of university members from Germany, Austria and Switzerland.     

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...     

New compact scrubber for odour removal in wastewater treatment plants.

This work presents the performances of a new odour scrubber. The reactor is packed with a new structure which enables co-current operations at high gas velocities. Energy consumption and removal efficiency of sulphur compounds by oxidative alkaline scrubbing were studied. The influence of both superficial gas (U(SG)) and liquid (U(SL)) velocities, ranging from 5.6 to 28 m.s(-1) and 0.016 to 0.055 m.s(-1) respectively, were quantified. Thus, the range of 0.5 to 5 liquid-to-gas mass ratio (L/G) was studied. A comparison has been made with a previous study on static mixers (SM) and with classical random packed towers (PT). It has been shown that superficial liquid and gas velocities have a significant influence on these parameters. Hydrogen sulphide (H2S) abatement reached values up to 99%. As concerns methylmercaptan (CH3SH), the maximal removal efficiency was 87%. As a result, if well scaled-up, our reactor can be a small single stage efficient apparatus for the elimination of low concentrations of sulphur compounds as H2S and CH3SH in high flow rates of polluted gas effluents.     

ICEAS工艺在污水处理厂中的运行控制实践

昆明第四污水处理厂采用ICEAS工艺,投产后运行情况良好,但也存在一些问题。针对出现的排泥不畅而导致MLSS控制不良、脱泥量不能满足生产工艺要求、污泥浓缩池不能进行有效浓缩等现象进行了分析。通过对MLSS、剩余污泥排放、DO、水温等工艺参数的调控,对生产工艺过程的摸索调试,以及对生产设备的更新改造,使污水处理厂工艺不但能达到良好的脱氮效果,而且能更好地满足除磷要求。     

生物除臭在污水处理厂中的应用

介绍了污水处理厂臭气测定方法、气味物质浓度设计值及除臭需满足的标准,并重点说明了厌氧池除臭工艺选择及生物除臭系统工程设计,最后根据除臭系统运行情况总结了设计经验。     

Mathematical modelling of small wastewater treatment plants: power and limitations.

Although mathematical modelling of biological wastewater treatment processes has proved to be valuable for large-scale WWTPs (wastewater treatment plants) little experience has been acquired in the mathematical modelling of small wastewater treatment plants. This paper seeks to evaluate the applicability of mathematical modelling on small systems, which are characterized by high fluctuations in organic and hydraulic loads and little possibility for control. In order to achieve this, the paper examines the different steps in a general modelling protocol. One important bottleneck for the general use of mathematical modelling of small systems that emerges is the frequent sampling and many analyses needed for characterization of the flows while its applicability is limited. On the other hand, the determination of the model structure of a small WWTP can be quite valuable. Experiments show that tracer tests should include tests with a highly varying influent flow rate to spot independent small internal flows as these can have a significant impact on the behaviour of peak concentrations throughout the system. In addition, the model structure determination can provide useful information on dead zones, short-circuiting and mixing behaviour in the plant.     

Seasonal profiles of human noroviruses and indicator bacteria in a wastewater treatment plant in Tokyo, Japan.

The seasonal profiles of microorganisms in raw sewage, secondary-treated sewage, and final effluent at a wastewater treatment plant in Tokyo, Japan, were quantitatively determined each month for one year, from July 2003 to June 2004. Human noroviruses, which were determined by real-time PCR, in raw sewage varied from 0.17-260 copies/mL for genotype 1 and from 2.4-1900 copies/mL for genotype 2, showing much higher values in winter, the epidemic season. The concentration of total coliforms, Escherichia coli, or F-specific phages in raw sewage was almost constant throughout the year. Human noroviruses of genotype 2 were removed most effectively (3.69 log10 on average) at the wastewater treatment plant, followed by E. coli (3.37 log10), total coliforms (3.05 loglo), F-specific phages (2.81 log10), and human noroviruses of genotype 1 (2.27 log10). The removal ratio of human noroviruses was almost constant, independent of the initial concentration of the viruses in raw sewage, which led to the increasing concentration of human noroviruses in final effluent in winter. None of the tested bacteria was judged to be a reliable indicator of human noroviruses in final effluent.     

Aeration of large-scale municipal wastewater treatment plants: state of the art.

Aeration is the most energy-intensive operation in wastewater treatment, amounting to 45-75% of plant energy costs. Fine-pore diffusers are today almost ubiquitous in municipal wastewater aeration, due to their advantageous aeration efficiency (mass of oxygen transferred per unit energy required). Nevertheless, older municipal treatment facilities and many industrial treatment plants are still equipped with coarse-bubble or surface aerators. Fine-pore diffusers are subject to two major disadvantages: a) fouling, if not cleaned periodically; b) decrease in oxygen transfer efficiency caused by dissolved surfactants. Coarse-bubble and surface aerators are typically not subject to the traditional problems affecting fine-pore diffusers. Nonetheless, they achieve oxygen transfer at the expense of increased energy intensity. The increased biomass concentration associated with high mean cell retention time (MCRT) operations has a beneficial effect on aeration. Nutrient-removing selectors are able to further increase aeration efficiency, as they sorb and utilize the readily available substrate which otherwise would accumulate at bubble surfaces and dramatically decrease aeration efficiency. We summarise here our 30-year long experience in aeration research, and results obtained with clean- and process-water tests are used to show the beneficial effects of high MCRT operations, the beneficial effect of selectors, and the decline of aeration efficiency due to dissolved surfactants.