An integrated environmental plan for the reuse of treated wastewater effluents from WWTP in urban areas

The reuse of treated wastewater effluents from wastewater treatment plants (WWTP) is a recent practice in the environmental restoration of marginal areas in combination with tree and shrub planting. In urban areas, an integrated approach to the application of this practice implies (a) reuse of treated domestic wastewater for irrigation of hardy plant species and (b) design of environmentally friendly outdoor landscape including the planting of species acceptable for irrigation with such kind of wastewater.     

Recovery of polluted lakes. a swedish research program on the effects of advanced waste water treatment and sewage diversion

In order to elucidate the effects of the effluents from advanced wastewater treatment plants for phosphorus removal, the National Swedish Environment Protection Board during 1972 started a program for analysing the conditions in a number of different recipient lakes. This study of recovery of polluted lakes also includes some recipient lakes from which sewage effluent will be completely diverted. This paper presents the program, some new methods used and the treatment plants and recipient lakes involved. The project. including 18 lakes and 15 sewage treatment plants, is running in cooperation with 13 Provincial Governments and 16 Municipalities. The efficiency of the sewage treatment plants, is continuously monitored by a new method called Minitest, and the nutrient loadings from these plants as well as from other sources are calculated.As the water quality of many recipient lakes showed great variations during the vegetation period (see Fig. 2), a need for a frequent sampling exists in these lakes.In order to simplify the sampling procedure sampling on the shore (after pumping water from the sampling point) has been introduced. Data obtained after analysing samples taken from a boat and samples from the same area taken on the shore after pumping through a 600 m plastic tube showed good agreement (see Table 2).The lake water samples are preserved by freezing, Analyses after rapid thawing showed that this method can be used also when determining from cell material easily leaking ions such as PO₄, NO₃ etc. (see Tables 3 and 4).The sewage treatment plants, the recipient lakes and some background data are presented in Tables 5 and 6. The water quality of the lakes is illustrated with the correlation between chlorophyll A and suspended solids (Fig. 3). The correlation coefficient = + 0–88. The first sign of lake recovery has been observed after an 85 per cent reduction of the waste phosphorus load. Post-precipitation (A1-sulphate) decreased the yearly load from 2000 kg P to 300 kg, which gave a 50 per cent reduction of the P content of the recipient water. Also the chlorophyll values decreased (Table 7).The role of nitrogen and phosphorus as algal growth limiting nutrients has been studied by using an algal assay procedure. N limited the growth of Selenastrum capricornutum in of the samples. In filtered lake water P was the growth limiting nutrient at total-P values below 0–05 mg 1⁻¹. Above 0·1 mg P 1⁻¹ N played the principal role. Between these values the growth was primarily limited by P or N or chelating agents (Fig. 4).     

问题优先级判别：生态保护修复中的核心 生态智慧之一

随着生态文明建设的推进,生态智慧在中国日趋重 要,特别是在生态保护修复领域。然而现状生态保护修复实践 存在一个难点：无数问题交叉在一起,如何在资源有限的情况 下,判别生态问题优先级并依次推进保护修复是一个需要智慧 的决策过程。针对这个瓶颈,立足国内外文献综述探究生态问 题优先级判别的不同思路与方法。研究发现：1)生态问题分 析的主要方法包括生境质量评价、生态系统服务和生态安全格 局;2)国外生态保护修复问题优先级判别存在3个不同的时段 与思路“生态重要性判定-投资收益判别-多目标优化决策”; 3)国内整体还是处于第一个生态重要性判定的阶段,对生境的 强化不足,偶有学者提及多目标决策优化。立足研究,对生态 保护修复过程中问题优先级判别提出了4点建议,以促使相关 决策更具生态智慧。     

Removal of estrogenicity in Swedish municipal sewage treatment plants

The human estrogen receptor alpha-test, hosted in a yeast strain, was used to quantify estrogenicity in three-week composite samples of untreated and treated effluents from 20 Swedish municipal sewage treatment plants. The treatment plants were selected to represent different treatment processes regarding chemical precipitation and microbial procedures. The discharge from Swedish domestic sewage treatment plants contained estrogenic compounds corresponding to <0.1-15 ng estradiol equivalents/L. Low levels of estrogenic activity were also found in a river receiving municipal effluents, 3.5-35 km downstream the outlet from a sewage treatment works. The range of estrogenicity in untreated, raw sewage effluents was found to be 1-30 ng estradiol equivalents/L. Generally, wastewater treatment reduced the estrogenicity and extended biological treatment was most effective in its removal. Activated sludge treatment tended to be more effective than trickling filters, whereas chemical precipitation using iron or aluminium salts without biological treatment showed little effectivity. The study showed that treatment methods in current use are able to eliminate or largely reduce estrogenicity in domestic wastewater.     

山水林田湖草生态保护修复治理工程预算定额标准建设探析

20世纪90年代以来,我国经济持续高速增长,伴随而来的是对矿产、森林、土地、水资源等自然资源过度的开发利用,导致我国部分地区生态系统严重退化。为从根本解决生态退化问题,国家自2016年以来,在全国范围内选择25个试点省份,先后组织开展了一系列山水林田湖草生态保护修复系统治理工程,拟由原来的单项工程整治转变为以山水林田湖草等多种自然资源要素构成的自然生态恢复治理为导向的保护修复。然而,由于目前国家没有制定统一的山水林田湖草生态保护修复治理工程预算定额标准,导致在工程调查、勘查、设计、施工、监理、验收、绩效评价等多个环节出现无统一依据可循、工程预算编制不科学、项目推进迟缓、工程无法验收、绩效无法合理评价等一系列问题的出现。作者从参与该项工程的具体实践入手,对制定山水林田湖草生态保护修复治理工程预算定额标准进行深入分析,提出了尽快研制山水林田湖草生态保护修复治理工程预算定额标准的建议,以促进该工程尽快推进实施。     

A conceptual ecosystem model of microbial communities in enhanced biological phosphorus removal plants

The microbial populations in 25 full-scale activated sludge wastewater treatment plants with enhanced biological phosphorus removal (EBPR plants) have been intensively studied over several years. Most of the important bacterial groups involved in nitrification, denitrification, biological P removal, fermentation, and hydrolysis have been identified and quantified using quantitative culture-independent molecular methods. Surprisingly, a limited number of core species was present in all plants, constituting on average approx. 80% of the entire communities in the plants, showing that the microbial populations in EBPR plants are rather similar and not very diverse, as sometimes suggested. By focusing on these organisms it is possible to make a comprehensive ecosystem model, where many important aspects in relation to microbial ecosystems and wastewater treatment can be investigated. We have reviewed the current knowledge about these microorganisms with focus on key ecophysiological factors and combined this into a conceptual ecosystem model for EBPR plants. It includes the major pathways of carbon flow with specific organic substances, the dominant populations involved in the transformations, interspecies interactions, and the key factors controlling their presence and activity. We believe that the EBPR process is a perfect model system for studies of microbial ecology in water engineering systems and that this conceptual model can be used for proposing and testing theories based on microbial ecosystem theories, for the development of new and improved quantitative ecosystem models and is beneficial for future design and management of wastewater treatment systems.     

数学模拟在污水处理厂节能减排中的应用和发展

在国内外节能减排的大背景下,污水处理厂面临着巨大的提标改造和节能减排压力。基于活性污泥数学模型的数学模拟技术在国内外许多污水处理厂的模拟仿真、运行诊断与工艺优化、升级评估、节能减排等方面得到广泛的应用,文章主要介绍了数学模拟技术在污水处理厂节能减排方面的发展和应用情况,并提出今后国内的主要研究方向。     

自然保护地生态系统修复研究进展与 修复策略

为应对全球气候变化、生物多样性丧失、生态系统 服务降低以及入侵物种增加等问题与挑战,有关保护地生态系 统修复的研究与实践亟待开展。通过文献整理、案例筛选与实 地调研相结合的方法,认识到保护地生态系统修复具有保护生 态系统完整性、促进净增益最优化以及协调生态保护与社区发 展等重要意义。在此基础上,阐述自然保护地生态系统修复 的原则、愿景、目标和指标;结合国内外典型案例说明自然 恢复、辅助再生、生态重建和保护保育4种修复模式的应用情 景。同时,根据文献分析总结中国生态系统的退化分布及其原 因,结合实地调研结果提出保护地生态系统修复的问题与关注 重点,并有针对性地提出6项具体的修复策略与3项建议。以 期在中国国土空间生态保护修复背景下,为自然保护地生态系 统修复活动的开展提供理论支持与案例参考。     

A mathematical model of a shallow and eutrophic lake (the Keszthely Basin, Lake Balaton) and simulation of restorative manipulations

Concern about the overall management of lakes has been growing, and a lake ecological model provides the guidelines necessary for such management. In this study, an ecological model describing the ecosystem of the Keszthely Basin, Lake Balaton, Hungary, one of the typical shallow and eutrophic lakes, was proposed. This model includes three types of zooplankton and two types of fish as well as two types of algae and nutrients. Parameters concerning the algae and fish were estimated based on observations in the basin between 1991 and 1995. The other parameters and the structure of the model were determined by our previous study. The parameters of the model were calibrated with the Monte Carlo technique, and its predictability was confirmed. The effects on the basin's ecosystem of three restorative manipulations, namely a biomanipulation, reduction of loading phosphorus, and dredging the sediment, were assessed by simulation studies using the proposed model. The simulation results indicated that a biomanipulation that removed 90% of the bream should suppress the growth of algae temporarily through bottom-up regulation; however, this effect seemed to not be perpetuated in this basin. The reduction of loading phosphorus seemed to be the most effective means to suppress algal growth, while dredging of sediment seemed to be the most desirable restoration method from the standpoint of the overall management of the lake, because it was expected to accelerate the growth of fish population as well as to suppress algal growth. Furthermore, the algal growth suppression mechanism of the dredging was discussed on the basis of the model calculations.     

Occurrence and removal of N-nitrosamines in wastewater treatment plants

The presence of nitrosamines in wastewater might pose a risk to water resources even in countries where chlorination or chloramination are hardly used for water disinfection. We studied the variation of concentrations and removal efficiencies of eight N-nitrosamines among 21 full-scale sewage treatment plants (STPs) in Switzerland and temporal variations at one of these plants. N-nitrosodimethylamine (NDMA) was the predominant compound in STP primary effluents with median concentrations in the range of 5-20 ng/L, but peak concentrations up to 1 μg/L. N-nitrosomorpholine (NMOR) was abundant in all plants at concentrations of 5-30 ng/L, other nitrosamines occurred at a lower number of plants at similar levels. From concentrations in urine samples and domestic wastewater we estimated that human excretion accounted for levels of <5 ng/L of NDMA and <1 ng/L of the other nitrosamines in municipal wastewater, additional domestic sources for <5 ng/L of NMOR. Levels above this domestic background are probably caused by industrial or commercial discharges, which results in highly variable concentrations in sewage. Aqueous removal efficiencies in activated sludge treatment were in general above 40% for NMOR and above 60% for the other nitrosamines, but could be lower if concentrations were below 8-15 ng/L in primary effluent. We hypothesize that substrate competition in the cometabolic degradation explains the occurrence of such threshold concentrations. An additional sand filtration step resulted in a further removal of nitrosamines from secondary effluents even at low concentrations. Concentrations released to surface waters were largely below 10 ng/L, suggesting a low impact on Swiss water resources and drinking water generation considering the generally high environmental dilution and possible degradation. However, local impacts in case a larger fraction of wastewater is present cannot be ruled out.     

A mercury-free accelerated method for determining the chemical oxygen demand of large numbers of water samples by autoclaving them under pressure with acid-dichromate

In order to fulfill the objective of a water control program based on frequent sampling in several wastewater treatment plants, rivers and lakes a simplified method for measuring COD was developed. The procedure, in this article called the RR-method, includes: small sample and reagent volume; rapid addition of a mixture of all reagents to the sample; exclusion of mercury; autoclaving at 120°C for 1 h in flasks with fitted glass stoppers. To avoid dilution before analysis the method has been adapted for wastewater (I: 10–300 mg O₂ l⁻¹) and fresh water (II: 10–100 mg O₂ l⁻¹).Parallel analyses on different types of water samples according to Standard Methods showed that the yield by the RR-method was about 10% lower (Table 2). With water from the wastewater treatment plant at Uppsala (COD around 20 mg O₂ l⁻¹), the two methods gave an identical result. The somewhat lower yield was mostly due to decreased dichromate concentration and oxidation temperature. The lower oxidation potential made correction for chloride interference unnecessary below 1 g Cl⁻ l⁻¹ (Table 1).The RR-method also showed a good correlation to the values for KMnO₄-consumption. Parallel analyses of 318 samples from 14 wastewater receiving lakes gave the correlation coefficient r = +0.90 (Fig. 1).     

西部小城镇污水厂、垃圾站的经济指标分析

在参考现有国内污水厂(站)经济指标及国内外经济指标费用模型的基础上,通过调查分析大量已建的西部城市污水处理厂的规模及投资情况,建立了适用于西部小城镇污水厂(站)的总的和分工艺的处理量一投资费用模型,并通过对运行成本构成的分析,构建了西部小城镇污水厂(站)的运行费用模型;同时,研究了全国采用卫生填埋工艺的城镇垃圾处理场的规模和投资情况,得出了西部小城镇垃圾处理设施的处理量一投资、单方库容投资费用模型及运行成本模型.     

Design of a novel constructed treatment wetland system with consideration of ambient landscape

A ‘fan-shape’ constructed wetland (CW) system is designed to treat domestic wastewater as well as to provide an aesthetically pleasing and environmentally sensitive landscape with ornamental plants for recreation. The system consists of two-stage subsurface horizontal flow CW cells with dewatered alum sludge cakes as the main substrate to ensure the treatment efficiency. The system is located in a new countryside village in Northwest China. The paper presents the design considerations of the CW together with the surrounding landscape to create an integrated CW (ICW). The study attempts to show how the wastewater infrastructure of CW can be an attractive feature in a community; bringing utility and beauty together, and serving needs for education, recreation and habitat conservation, through integrating engineering and landscape design.     

Evaluation of the effects of greywater reuse on domestic wastewater quality and quantity

This simulation study, based on experimental and literature data, evaluates the influence of onsite greywater reuse on domestic wastewater quality and quantity. For this, three scenarios were studied: no reuse; reuse for toilet flushing; reuse for toilet flushing and garden irrigation. Light greywater reuse reduced the daily household wastewater flows by 25–40%. These reductions mainly occurred during the morning and evening peak wastewater generation. Although daily loads of all pollutants decreased, their concentrations in the discharged wastewater increased owing to exclusion of potable water from the wastewater and replacing it by treated light greywater. The proportional concentration increase of most pollutants was lower than the decrease in wastewater discharge, due to degradation during treatment. The highest concentration increase occurred during the morning peak, coinciding with the highest flow reduction. This study is a first step towards quantification of the effects of onsite greywater reuse on sewers and wastewater treatment plants.     

福建地区自然保护区内的生态修复探索与 实践——以福建闽清黄楮林自然保护区石潭溪 片区生态修复项目为例

随着中国社会经济的发展，人们越来越重视生态文 明建设。自然保护区可持续发展建设是生态文明建设中最重要 的一部分，它不仅维持着人与自然的平衡，更是在生态平衡和 社会经济的可持续发展中发挥着至关重要的作用。闽清黄楮林 自然保护区石潭溪片区生态修复工程项目通过分析片区内出现 的生产及生活废弃地污染、山林地裸露、水土流失等系列生态 问题，融入山水林田湖草“生命共同体”系统理念，以“生态 保护、生态修复、水系修复和人居环境治理”为主要布局思 路，并以“四层保障体系”为框架进行合理的生态修复，以期 将石潭溪片区建设成为“生态优良、物种丰富、景观多样、功 能齐全”的生态保护修复示范性片区，为后期我国自然保护区 的生态景观改造提供相关的设计思路与实践参考。     

Trends of phosphorus, nitrogen and chlorophyll a concentrations in Finnish rivers and lakes in 1975–2000

During recent decades the amounts of nutrients discharged to Finnish surface waters have markedly decreased. This has been achieved by considerable investments in water protection, which were made mainly to improve municipal and industrial wastewater purification. We investigated whether these water protection measures have decreased phosphorus and nitrogen concentrations in Finnish rivers and lakes. In addition, possible trends in chlorophyll a concentrations in lakes were studied. The data consisted of a total of over 68 000 monitoring results of 22 rivers and 173 lakes (or sub-basins of lakes) with different types of catchment areas. The study period covered the years 1975–2000 and the non-parametric Kendall Tau b and Seasonal Kendall tests were applied for detecting trends. Decreasing nutrient concentration trends were typical in many lakes and rivers earlier polluted by municipal and industrial wastewaters. Increasing nutrient concentration trends were common in smaller rivers and lakes receiving diffuse loading from agriculture. The results show that the investments directed towards wastewater purification have effectively improved the quality of Finnish inland waters. However, no clear effects of decreasing non-point loading were found. Thus, more effective measures should be directed towards decreasing non-point source loading.     

二氧化氯对污水厂出水的消毒及综合影响研究

介绍了以二氧化氯作为大型城市污水处理厂出水消毒剂的生产性应用情况,系统地研究了二氧化氯在取得良好消毒效果的同时,对出水中BOD5、COD、NH_3-N、SS、TP的影响.评估了二氧化氯作为污水处理厂出水消毒剂的优势,以及对出水水质的改善效果,从而为其在大型城市污水厂的推广奠定了基础.     

Estimation of greenhouse gas emissions from municipal wastewater treatment systems in India

Greenhouse gas (GHG) emissions generated from municipal wastewater treatment plants in India is estimated in this study. The emissions from the wastewater treatment process as well as from the electricity used during the treatment process are estimated by using the methodology of Intergovernmental Panel on Climate Change. The present treatment plants of capacity 15 997 million litres per day (MLD) contributes towards GHG emissions of 7.3 Mt of CO₂‐eq/year. The future GHG emissions would depend upon the treatment technology used for treating 34 109 MLD of untreated wastewater. The highest GHG emissions would occur if all new wastewater treatment plants are based on upflow anaerobic sludge blanket technology, 19.66 Mt CO₂‐eq/year and lowest if sequential batch reactor technology is adopted, 2.93 MtCO₂‐eq/year.     

Demonstration of nitrogen removal via nitrite in a sequencing batch reactor treating domestic wastewater

Nitrogen removal via nitrite, as opposed to the traditional nitrate, may be beneficial for carbon-limited biological wastewater treatment plants. However, reliable termination of nitrification at nitrite (nitritation) has proved difficult in the treatment of domestic wastewater. In this study, nitritation was attained in a sequencing batch reactor (SBR) with pre-denitrification treating domestic wastewater (total Kjeldahl nitrogen (TKN) concentration of about 43 mg NL(-1)) by aerobic duration control. The aerobic duration control strategy terminates aeration upon completion of ammonium oxidation with accumulated nitrite still remaining. The SBR was purposefully operated such that the influence of other known selection factors for nitritation was absent. The process proved effective in achieving a steady state whereby over 80% nitritation was sustained. Investigation of the cause of nitritation by a calibrated ammonium and nitrite oxidation model showed aerobic duration control as the key factor leading to nitritation.     

Characterization of endotoxic indicative organic matter (2-keto-3deoxyoctulosonic acid) in raw and biologically treated domestic wastewater

The aim of this research is to characterize the organic matter showing endotoxicity in domestic wastewater. It is assumed that endotoxicity is caused by lipo-polysaccharide (LPS), particularly large and hydrophobic molecules. In this study, a batch experiment (decay test for 12 h) was conducted to confirm whether LPS is the cause of endotoxicity or not. 2-keto-3deoxyoctulosonic acid (KDO) was used as an indicator of presence of LPS.A size and structural characterization of several samples from raw and domestic wastewater was also carried out in order know which fractions are causing endotoxicity. Endotoxin and KDO patterns were found to be similar, peaking at the same time. Thus, organic matter showing endotoxicity, such as LPS was released in the decay test. Moreover, the organic matter released from bacteria during decay test was partly biodegradable. Results from size characterization (Molecular Weight Distribution) showed that the majority of endotoxin (up to 82%), in domestic sewage and secondary effluents,is composed of molecules larger than 100 kDa and less than 0.1 μm. Similarly, structural characterization (hydrophobic and hydrophilic) showed that the majority of endotoxin, ranging from 59% to 83% of the total endotoxicity, is hydrophobic fractions. Therefore, removing large and hydrophobic molecules from wastewater can be an effective way to achieve a significant decrease in its endotoxicity.