Climate Change Adaptation Indicators to Assess Wastewater Management and Reuse Options in the Mekong Delta, Vietnam

Climate change adaptation indicators have played a critical role in the increased understanding of potential climate change impacts. In this research, 6 climate change adaptation indicators were identified for Can Tho City in the Mekong Delta of Vietnam: (1) Rice production from wastewater during winter-spring crop; (2) % of irrigation water demand satisfied by treated wastewater; (3) % of nutrient demand satisfied by treated wastewater; (4) % remaining flow downstream of Can Tho in the Hau River; (5) environmental benefits; and (6) total investment cost for wastewater treatment. These indices were selected to assess various options/strategies for wastewater management and reuse in Can Tho City as a means to improve the City’s resilience to climate change. From an environmental perspective, this study shows the benefits for Can Tho City to set up a strategy to treat and reuse wastewater from catfish farming as the priority among four assessed scenarios with different climate change impact factors. It is concluded that adaptation can be assessed by the indicators because they can define whether adaptation policies and measures are implemented and whether vulnerability is reduced through effective actions.     

Revealing microbial community structures in large- and small-scale activated sludge systems by barcoded pyrosequencing of 16S rRNA gene

The diversity of bacterial groups in activated sludge from large- and small-scale wastewater treatment plants was explored by barcoded pyrosequencing of 16S rRNA gene. Activated sludge samples (three small and 17 large scale) were collected from 12 wastewater treatment plants to clarify precise taxonomy and relative abundances. DNA was extracted, and amplified by 4 base barcoded 27f/519r primer set. The 454 Titanium (Roche) pyrosequences were obtained and analyses performed by Quantitative Insight Into Microbial Ecology (QIIME) with around 100,000 reads. Sequence statistics were computed, while constructing a phylogenetic tree and heatmap. Computed results explained total microbial diversity at phylum and class level and resolution was further extended to Operational Taxonomic Unit (OTU) based taxonomic assignment for investigating community distribution based on individual sample. Composition of sequence reads were compared and microbial community structures for large- and small-scale treatment plants were identified as major phyla (Proteobacteria and Bacteroidetes) and classes (Betaproteobacteria and Bacteroidetes). Also, family level breakdowns were explained and differences in family Nitrospiraceae and phylum Actinobacteria found at their species level were also illustrated. Thus, the pyrosequencing method provides high resolution insight into microbial community structures in activated sludge that might have been unnoticed with conventional approaches.     

Redesigning wastewater infrastructure to improve resource efficiency

Resource efficiency of wastewater management is a question of optimizing at the same time the management of resources in wastewater (e.g. water), the resources spent on treatment and transport (e.g. energy), the natural resources to protect (e.g. the receiving waters), and the anthropogenic resources (e.g. capital). For instance, wastewater can be treated to any given quality, but only at the expense of energy and investment costs. Today, many up-coming problems are solved incrementally, leading to resource consuming solutions optimized for water pollution control in well off countries, whereas large parts of the world have at the best very simple wastewater treatment. From a global point of view, a system change is necessary in order to solve the immense problems arising from global population growth, urban development and climate change. Source separation is a promising concept for resource efficient wastewater management, but a more concerted effort is necessary from the international community in order to develop competitive technologies and overcome the inflexibility of the present end-of-pipe technology. Much more research and development are necessary, not only in the area of engineering, but also with respect to the socio-economic dimensions, especially in the area of regulation, suitable governance and management models, and concerning the involvement of industrial partners.     

浙江小型农村饮用水工程管理模式的可拓评价

农村饮用水工程运行管理是现阶段农村供水工程研究的一个热点,而对小型饮用水工程运行管理模式研究较少.经调研,目前浙江省小型饮用水工程主要有3种运行管理模式:村集体管理、用水户协会管理、承包管理.建立有效的运行管理评价模式对小型饮用水工程研究具有重要意义.提出了一种基于可拓评价的小型农村饮用水工程管理模式合格度分析方法,运...     

Performance of membrane bioreactors used for the treatment of wastewater from the chemical and textile industries.

Within the scope of the study, nine waste waters from the chemical and textile industries were treated in bench-scale (laboratory scale) and small-scale (pilot scale) membrane bioreactors. Depending on wastewater characteristics, the resulting performance varied significantly. It was observed that MBR effectiveness was determined primarily by the degree of biodegradability of the wastewater. In the course of several months of operation, no significant changes associated with the complete retention of the biomass by the membranes were observed. In some cases, it was possible to improve effluent quality by using smaller molecular separation sizes. The flux performance of the membrane modules was dependent on wastewater composition. Occasionally, non-degradable macromolecular substances concentrated in the bioreactor, resulting in strongly reduced filterability and flow performance of the membrane modules, consequently also reducing the economic viability of the process. The results demonstrate that wastewater-specific pilot tests are absolutely necessary, in particular if the technology is to be used for new applications.     

Technology for sustainability: the role of onsite, small and community scale technology.

An overview of available onsite, small and community scale wastewater treatment technology shows that it is diverse compared to current technology for centralised collection and treatment of wastewater. An analysis of the onsite, small and community scale technology for achieving sustainability shows that it more conducive to achieving sustainability than the centralised technology. It is likely, however, that its application is in remote and rural areas, where the technology should be improved and integrated with other technology sectors (energy, food production) for improved sustainability. Opportunities exist in new urban developments to achieve similar outcomes, but concerted efforts are required to demonstrate or showcase sustainability benefits in real situations. A huge potential also exists for the use of onsite, small and community scale technology in developing countries for achieving the same sustainability outcomes. It is likely to succeed if the technology is modified to be of lower cost but based on the same science, and that research, development and demonstrations in developed countries are shown to be successful.     

Status analysis and strategic framework for sanitation management in Asia and Africa.

Following rapid population increase and industrial development, the ever increasing environmental pollution and the associated sanitation-related problem are no longer regional or local but have become an issue requiring global-dimensional concern and the provision of problem-solving alternatives. Especially, since most problems result from inappropriate sewerage and the lack of sewage treatment system are in a serious state occurring in economically underdeveloped regions, and as such, their significance is enormous. The United Nations Environment Programme (UNEP) has been making efforts to establish the technology selection methodology applicable in developing countries, through the accurate status, investigation and analysis of the wastewater management state in Asian and African regions, and the sanitation management guideline utilisable by political leaders or decision-makers. As part of this effort, the Korea Institute of Water Environment (KIWE), together with the UNEP, selected China and Vietnam (in Asia) and Kenya and Ethiopia (in Africa) as subject countries to investigate and perform on-site sanitation management investigations and analysis in this research. Results obtained from the on-site investigation were analysed, and in order to be helpful in establishing a strategy for sanitation management in underdeveloped countries, the strategic framework (SF) has been made based on characterised results.     

The role of membrane technology in sustainable decentralized wastewater systems.

Decentralized wastewater treatment has the potential to provide sanitation that meets criteria for sustainable urban water management in a manner that is less resource intensive and more cost effective than centralized approaches. It can facilitate water reuse and nutrient recovery and can potentially reduce the ecological risks of wastewater system failure and the community health risk in a wastewater reuse scheme. This paper examines the potential role of membrane technology in sustainable decentralized sanitation. It is argued that the combination of membrane technology within decentralized systems can satisfy many of the criteria for sustainable urban water management. In particular, the role of membranes as a dependable barrier in the wastewater treatment process can increase system reliability as well as lowering the latent risks due to wastewater reuse. The modular nature of membranes will allow plant size to range from single dwellings, through clusters to suburb size. It is concluded that realization of the potential for membrane-based technologies in decentralized wastewater treatment will require some progress both technically and institutionally. The areas where advances are necessary are outlined.     

Reviewer's response: the beginning of an important dialogue

This article examines the historical evolution of participatory water management in coastal Bangladesh. Three major shifts are identified: first, from indigenous local systems managed by landlords to centralized government agencies in the 1960s; second, from top-down engineering solutions to small-scale projects and people’s participation in the 1970s and 1980s; and third, towards depoliticized community-based water management since the 1990s. While donor requirements for community participation in water projects have resulted in the creation of ‘depoliticized’ water management organizations, there are now increasing demands for involvement of politically elected local government institutions in water management by local communities.     

Evaluation of electrochemically generated ozone for the disinfection of water and wastewater.

Effective wastewater treatment is critical to public health and well-being. This is especially true in developing countries, where disinfection of wastewater is frequently inadequate. People who live in these areas may benefit from wastewater disinfection using ozone. This study evaluated the ability of a new electrochemical process of ozone generation, which produced ozone continuously at high pressure and concentration by the electrolysis of water, to disinfect tap water and secondarily treated wastewater. Inactivation of Klebsiella terrigena, Escherichia coli, MS2 bacteriophage and poliovirus 1 was evaluated first in reverse osmosis (RO) treated water. Inactivation of K. terrigena (6-log), E. coli (6-log), MS2 (6-log) and poliovirus 1 (>3-log) was observed after 1 min of ozonation in a 1 L batch reactor. Experiments were then performed to assess the microbiological impact of disinfection using ozone on secondarily treated municipal wastewater. The effect of ozonation on wastewater was determined for total and faecal coliforms, bacteriophages and heterotrophic plate count (HPC) bacteria. Electrochemical ozone generators provided an effective, rapid and low-cost method of wastewater disinfection. Based on the results of this research, electrochemically generated ozone would be well suited to remote, small-scale, disinfection operations and may provide a feasible means of wastewater disinfection in developing countries.     

The application of economic-engineering optimisation for water management in Ensenada, Baja California, Mexico.

Mathematical optimisation is used to integrate and economically evaluate wastewater reuse, desalination and other water management options for water supply in Ensenada, Baja California Mexico with future levels of population and water demand. The optimisation model (CALVIN) is used to explore and integrate water management alternatives such as water markets, reuse and seawater desalination, within physical capacity constraints and the region's water availability, minimising the sum of economic costs of water scarcity and operating costs within a region. The modelling approach integrates economic inputs from agricultural and urban water demand models with infrastructure and hydrological information, to identify an economically optimal water allocation between water users in Ensenada. Estimates of agricultural and urban economic water demands for year 2020 were used. The optimisation results indicate that wastewater reclamation and reuse for the city of Ensenada is the most economically promising alternative option to meet future water needs and make water imports less attractive. Seawater desalination and other options are not economically viable alone, but may have some utility if combined with other options for the Ensenada region.     

Cost Analysis of Water Quality Assessment Using Multi-Criteria Decision-Making Approach

In modern competitive markets, cost and quality parameters are the two main factors. So, it is essential to study their relationship, especially in leading industries such as urban public service companies. Consequently, manufacturers always try to reduce production costs and improve product quality and services to consumer expectations. Also, the concerns of the new century in the field of fresh water and the reduction of its resources related to global warming have increased the costs of quality and supply of freshwater. Therefore, in this research, in order to estimate the quality costs in the field of water resources and wastewater management and identify the option that creates the most cost, in the first step, the “Prevention, Assessment, and Failure (PAF)” model was used to select cost-imposing options in organizational quality analysis. After determining the main options, appropriate criteria and sub-criteria were selected under the main study area (water and wastewater resources management). In the next step, a “Multiple-Criteria Decision-Making (MCDM) “ method based on the “Fuzzy Analytical Hierarchy Process (FAHP)” and “Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS)” method was used to identify the option that creates the most cost. The results show that The highest cost of quality in the water and wastewater industry and its management are related to “Assessment Costs” and account for 36.55% of total costs. Also, The lowest cost of quality in the water and wastewater industry is related to “Preventive Costs” and accounts for only 12.18% of the total cost. In addition, the expert’s opinion shows that the effect of increasing credit with 34.01% has the greatest weight, and this criterion is the most essential in water and wastewater resources management.

     

Evaluating the application of a decision support system in identifying adequate wastewater treatment for small communities. A case study: the Fluvia River Basin.

The identification of adequate wastewater treatment for small communities is a complex problem since it demands a combination of data from different sources, such as aspects of the community and landscape, the receiving environment and the available wastewater treatment technologies. The Catalan Water Agency (Agència Catalana de l'Aigua) considered using an EDSS (Environmental Decision Support System) as a tool to help water managers select the most adequate treatment for the urban wastewater of nearly 3,500 small communities in Catalonia (Spain). From that moment, EDSS was applied to all the river basins in Catalonia. In this paper the authors present the results obtained for the 76 small communities located in one of these river basins: the Fluvia River Basin. The characteristics of the community used in the reasoning process of the EDSS, the list of selected wastewater treatment alternatives, the technical environmental justification for the selected treatments and the reasons for discarding, favouring or disadvantaging them are presented. Finally, some results for the Fluvia River Basin are compared with those obtained in other Catalan river basins with different characteristics in order to evaluate which are the significant features in identifying adequate wastewater treatments.     

Biological wastewater treatment by a bioreactor with repeated coupling of aerobes and anaerobes aiming at on-site reduction of excess sludge.

Activated sludge has been widely used in wastewater treatment throughout the world. However, the biggest disadvantage of this method is the by-production of excess sludge in a large amount, resulting in difficulties in operation and high costs for wastewater treatment. Technological innovations for wastewater treatment capable of reducing excess sludge have thus become research topics of interest in recent years. In our present research, we developed a new biological wastewater treatment process by repeated coupling of aerobes and anaerobes (rCAA) to reduce the excess sludge during the treatment of wastewater. During 460-day continuous running, COD (300-700 mg/L) and TOC (100-350 mg/L) were effectively removed, of which the removal rate was above 80 and 90%, respectively. SS in the effluent was 13 mg/L on average in the rCAA bioreactor without a settling tank. The on-site reduction of the excess sludge in the rCAA might be contributed by several mechanisms. The degradation of the grown aerobes after moving into the anaerobic regions was considered to be one of the most important factors. Besides, the repeatedly coupling of aerobes and anaerobes could also result in a complex microbial community with more metazoans and decoupling of the microbial anabolism and catabolism.     

Spatial and temporal variations in algal blooms in the coastal waters of the western South China Sea

Algal blooms occur frequently in the coastal waters of the western South China Sea (SCS). This paper reports spatial and temporal variations of algal bloom events in these waters from 1993 to 2007. Twenty-five algal bloom events occurred in summer in the coastal waters of South and Central Vietnam where they were associated with wind-induced, coastal, nutrient upwelling and river discharges; a further eight events occurred in the coastal waters of North Vietnam. A greater number of algal bloom events were observed in 1999 and 2002, and were accompanied by several previously unobserved species for the study period. These events may be related to the El Niño events of 1998 and 2002. Furthermore, the bloom-causative species Trichodesmium erythraeum (Cyanophyta) entirely dominated the phytoplankton community of algal blooms during 1993–1999 whereas the species Phaeocystis globosa (Haptophyta) dominated blooms after 2002. This study establishes a basis for further long-term research of algal bloom event variations, and provides a compiled scientific reference that may be used for later prediction of Harmful algal blooms (HABs).     

小型农田水利工程可持续运行管理探析

小型农田水利工程作为农业发展的基本保障设施,与农民、农业有着密不可分的关系,同时其也是水利体系的重要组成部分。就目前形势分析,实现小型农田水利工程的可持续运行是推动我国小型水利事业发展的关键。因此,从管理的角度,对小型农田水利设施可持续运行问题进行了探究,对当今小型农田水利工程管理存在的问题及其原因进行了分析,提出了实现小型农田水利工程可持续运行管理的策略。     

Sludge thickening performance of mesh filtration process.

Small-scale wastewater treatment facilities play an important role in improving the aquatic environment in many countries. Although sludge treatment is essential for overall wastewater treatment, it is difficult for small-scale facilities to use mechanical equipment or other facilities. As the first step of the sludge treatment, it is important to develop a convenient sludge thickening process for small-scale facilities. In this work, we examined the sludge thickening performance of a mesh filtration system: the mesh opening sizes of 100-500 microm, and the sludge (3,000-9,000 mg-SS/L) was obtained from a domestic wastewater treatment facility. The filtration was carried out only under the hydraulic pressure between the water level and the effluent port connected to the mesh filter module. The sludge reduction rates were in the range of 85-95% for 6-7 h; the initial filtration rate was very high, but the rate decreased with a decrease in hydraulic pressure due to the reduction of the water level in the vessel. In addition, the effluents (passed through the mesh) contained very low SS and could be directly discharged into the environment.     

What drives communities' decisions and behaviours in the reuse of wastewater.

This paper outlines a five year investigation which aimed to develop a measurement to predict community intended behaviour in relation to the reuse of wastewater. It has been apparent that communities support the concept of water reuse as a means of responsible water resources management. However, reactions from people when it comes to actually using the recycled water are frequently quite different, particularly when it involves close personal contact or ingestion of the water. Little has been known of how people make their decisions to accept or reject schemes. Therefore, a research program was designed to systematically identify, measure and test the major factors that govern people's decision-making. A social experiment was designed whereby a large group of random community members participated in tasting and swallowing what they believed to be recycled water from different sources and products grown with recycled waters. This provided an immediate experience for the development of measures of psychological and other factors in decisions to taste and/or swallow. This then formed the basis for whole of city surveys which tested and refined an hypothesised model of intended behaviour, and three case studies over time which sought to replicate the model.     

Reducing reservoir impacts and improving outcomes for dam‐forced resettlement: experiences in central Vietnam

The present study focuses on the growing problem of the impacts of human displacement resulting from hydropower dam construction, within the context of the integrated lake basin management of dam reservoirs. Dam‐forced displacement and resettlement can pose severe challenges to the environmental, economic and social sustainability of a reservoir basin. A case study in Quang Nam Province, central Vietnam, suggests that many resettled communities experience impoverishment due to the lack of adequate replacement land, declines in supplemental food sources and reduced access to natural resources. In response to such situations, resettled residents may (i) destroy lake catchment forests for the purpose of converting them to farmland or engage in illegal logging; (ii) increase agrichemical inputs on reduced land, thereby polluting run‐off and groundwater; and (iii) place increased pressure on fish stocks and wildlife. Examples are provided from central Vietnam to illustrate the need for applying management approaches that allows the affected people to become beneficiaries of dam projects and for including civil society organisations in resettlement planning. The hydropower authority can fund benefit‐sharing mechanisms, including village‐level electrification and payment for environmental services schemes, in which resettled populations are paid for forest maintenance and protection to prevent erosion and deforestation, and reservoir access can be provided for fishing, aquaculture and agriculture. Civil society organizations can advocate for residents’ interests and for reallocation of protected forest land for community forestry. These approaches can be supported by an inclusive reservoir management board working to achieve environmental sustainability, economic growth and social equity.     

Urban and agricultural competition for water,and water reuse

Competition for water can be resolved by construction of more facilities for storing water in wet years for use in dry years, by weather modification, watershed management, urban and agricultural water conservation, reuse of sewage effluent and other wastewater, desalination of saline water, water banking and transfer of water rights or other changes in water use. Reuse of wastewater requires treatment so that the water meets the quality requirements for the intended reuse. Groundwater recharge and recovery can play an important role in the treatment and storage of wastewater for reuse—agricultural, urban, and industrial, as well as potable. Often, water shortages are only shortages of cheap and abundant water, and competition problems can be resolved by good planning and management if the public is willing to pay the price and to accept changes in water use.