Environmental assessment and cost estimation of drinking water and wastewater systems for transition areas in Sweden

In the Stockholm region there are around 90,000 households with single systems. These households cause larger phosphorus flows to the Baltic Sea than the 1.8 million people connected to four advanced large-scale treatment plants in the same region. According to city plans, some of these areas with on-site systems in transition to permanent living shall be connected to central systems. The problem is however that this sewer system will take decades to complete. It is also not ensured whether or not all peripheral areas with on-site systems could be connected to the central systems. To help support environmental decisions for the selection of wastewater systems for these areas, an Excel-based model has been developed where the cost for the systems can be assessed and evaluated in relation to their environmental impact. The model deals with two types of environmental issues: substance flow analysis and energy analysis. The cost part considers investigations, investments, design, operation, maintenance and supervision, and calculates total annual cost for the water and wastewater system per person.     

Treatments of oil-refinery and steel-mill wastewaters by mesocosm constructed wetland systems.

In this study, two types of industrial wastewater, oil-refining and steel-milling, were selected for investigating their feasibility of treatment by mesocosm constructed wetland systems. The secondly treated effluents from the wastewater treatment plants were directly discharged into the systems controlled at different flow rates. Three wetland mesocosms were installed in the two industries: mesocosms A and B were in the oil refinery, and mesocosm C was in the steel mill. The substratum media used in wetland systems were sand (mesocosm A) and gravel (mesocosms B and C), while the vegetation types selected were reeds (mesocosms A and B) and mixed species of reeds and cattails (mesocosm C). The flow regimes were controlled as free water surface (FWS) and subsurface flow (SSF) for the sand- and gravel-beds, respectively. According to the experimental results, we found that the system treating oil-refining wastewater performed better than that treating steel-milling wastewater learned by comparing the removal efficiencies of COD, total N and total P. In addition, it was found that for oil-refining wastewater treatments, the SSF wetland system (mesocosm B) performed better than FWS (mesocosm A) wetland system when comparing both of their removal of pollutants and growth of vegetation. Besides, the effluents from these two industrial wetland treatment systems might be reclaimed and reused for boiler water, cooling, cleaning and miscellaneous purposes in industries. Further treatments are required if the constructed wetland effluents are thought about being reused for processing in industries.     

Integrated soft sensor model for flow control.

Tighter discharge permits often require wastewater treatment plants to maximize utilization of available facilities in order to cost-effectively reach these goals. Important aspects are minimizing internal disturbances and using available information in a smart way to improve plant performance. In this study, flow control throughout a large highly automated wastewater treatment plant (WWTP) was implemented in order to reduce internal disturbances and to provide a firm foundation for more advanced process control. A modular flow control system was constructed based on existing instrumentation and soft sensor flow models. Modules were constructed for every unit process in water treatment and integrated into a plant-wide model. The flow control system is used to automatically control recirculation flows and bypass flows at the plant. The system was also successful in making accurate flow estimations at points in the plant where it is not possible to have conventional flow meter instrumentation. The system provides fault detection for physical flow measuring devices. The module construction allows easy adaptation for new unit processes added to the treatment plant.     

Utilising integrated urban water management to assess the viability of decentralised water solutions

Cities worldwide are challenged by a number of urban water issues associated with climate change, population growth and the associated water scarcity, wastewater flows and stormwater run-off. To address these problems decentralised solutions are increasingly being considered by water authorities, and integrated urban water management (IUWM) has emerged as a potential solution to most of these urban water challenges, and as the key to providing solutions incorporating decentralised concepts at a city wide scale. To incorporate decentralised options, there is a need to understand their performance and their impact on a city's total water cycle under alternative water and land management options. This includes changes to flow, nutrient and sediment regimes, energy use, greenhouse gas emissions, and the impacts on rivers, aquifers and estuaries. Application of the IUWM approach to large cities demands revisiting the fundamental role of water system design in sustainable city development. This paper uses the extended urban metabolism model (EUMM) to expand a logical definition for the aims of IUWM, and discusses the role of decentralised systems in IUWM and how IUWM principles can be incorporated into urban water planning.     

Environmental Assessment of a Wastewater System under Water demand management policies

Water demand management policies (WDMPs) are considered necessary for sustainable water supplies to affect urban water infrastructures from various aspects, which has less attention in previous studies. Hence, this study is focused on proposing a comprehensive novel approach to provide helpful insight for researchers and policy-makers towards the environmental effects of applying WDMPs on wastewater systems. The life cycle assessment (LCA) method assesses the environmental burdens of utilizing WDMPs in the operation stage of a real wastewater system in Baharestan city, Iran. A detailed inventory is considered, including maintenance of sewer pipelines, replacement of manhole covers, civil works, road rehabilitation, energy consumption, chemical usage, transportation, and air emissions of the WWCN and WWTP using SimaPro software. Results show that a significant part of the environmental impacts accounts for energy consumption, which has strong effects on most midpoint categories and has a great change in different scenarios. For example, energy’s impact on the global warming category is reduced from around 18.4 to 8.5 million kg CO₂ eq. from scenario 0 to scenario 4 with an average of 165.4 to 94 L/capita/day of wastewater production, respectively. Besides, the results demonstrate that the environmental effects driven by the WWTP are eightfold the corresponding WWCN’s impacts. Overall, the outcomes from the present study reveals that implementing WDMPs can lead to diminishing environmental impacts. For instance, reducing wastewater production up to 68% can decrease 18% of the WDMPs’ environmental impacts of the wastewater system in the operation stage.

     

污水处理厂生命周期评价及不同工艺污水处理系统的环境影响比较分析

对某A2／O工艺城市污水处理厂施工建造和运营维护阶段所造成的环境影响进行生命周期评价,并以绿色税收为参考指标概算各环境影响指标造成的经济负担,同时对采用不同污水处理方式的污水处理厂的生命周期评价结果进行比较。结果表明：A2／O工艺城市污水处理厂生命周期内造成的环境影响主要来自运营维护阶段的能量消耗,对水体富营养化的影响较大;相对于某湿地污水处理系统,A2／O工艺城市污水处理厂对非生物资源消耗较大,但在大气酸化、光化学氧化以及全球变暖等方面的影响较小;相对于五阶段Bardenpho工艺,A2／O工艺对水体富营养化具有较大影响,但在非生物资源消耗、全球变暖、光化学氧化、大气酸化等方面影响较小。     

Study on risk management of heavy metals for reuse of biosolids.

The behaviour of heavy metals was investigated at 22 wastewater treatment plants (WWTPs). In addition, the survey of heavy metal balance was conducted in detail at one WWTP. For the measurement, 22 types of heavy metals were selected from the chemical materials of pollutant release and transfer register (PRTR). There were some heavy metals, which were detected not in wastewater but in dewatered sludge. By means of the detailed survey at one WWTP, 60 to 80% of some heavy metals, such as B, Mn, Co, Ni and Mo, were discharged with treated water. According to the results of PRTR, Zn, B and Mn accounted for a large part of the discharge into the water course. To estimate the behaviour of heavy metals in the environment, leaching tests were applied to the products made of biosolids. During a series of leaching tests for building materials, it was observed that the concentration of heavy metals was very small, but the ratio of increase keeps a constant value. Therefore, it was considered that the acid extractable contents of heavy metal would be important.     

Modelling Impacts of Land Cover Change on Critical Water Resources in the Motueka River Catchment, New Zealand

After the SWAT (Soil and Water Assessment Tool) model was calibrated and validated to historic flow records for the current land use conditions, two additional land cover scenarios (a prehistoric land cover and a potential maximum plantation pine cover) were used to evaluate the impacts of land cover change on total water yields, groundwater flow, and quick flow in the Motueka River catchment, New Zealand. Low-flow characteristics and their potential impacts on availability for water abstraction and for support of in-stream habitat values were focused on. The results showed that the annual total water yields, quick flow and baseflow decreased moderately in the two scenarios when compared with the current actual land use. The annual water balance for the pine potential land cover scenario did not differ substantially from the prehistoric scenario for the catchment as whole. However, there were more notable differences among individual tributary catchments, which could be attributed to the relative area of land cover altered and location of those catchments. Simulated low flows for the prehistoric and potential pine land cover scenarios were both significantly lower than the low flows for the current land use. In summary, under the current land use conditions, both annual water yield and low flow are higher than was the case before human intervention in the area or in a maximum commercial reforestation scenario.     

EVALUATING TRADEOFFS BETWEEN ENVIRONMENTAL FLOW PROTECTIONS AND AGRICULTURAL WATER SECURITY

River basin managers responsible for water allocation decisions are increasingly required to evaluate tradeoffs between environmental flow protections and human water security. However, the basin‐scale effects of environmental flow regulations on water users are not well understood, in part because analyses are complicated by the spatial and temporal variation in water availability, human demands, and ecosystem needs. Here, we examine alternative regional environmental flow policies and their effects on a distributed network of water users in a small (182 km²) river basin in coastal California. We use a hydrologic model to simulate water diversion operations under three policy scenarios and quantify potential impacts to bypass flows for adult migrating salmon and agricultural water storage. The results indicate that there are inherent tradeoffs between environmental flows and agricultural water security, with the most restrictive environmental policy associated with the greatest impacts to water users. Surprisingly, the moderate environmental flow policy had larger impacts to bypass flows than the unregulated management scenario, suggesting that ecological benefits of the moderate policy are small relative to the adverse effects on agricultural water users. Conflicts between environmental and human water needs were greatest in upper catchments (<2.5 km²), where flow protections caused the greatest reduction in water storage. Although natural supplies were adequate for meeting water needs in most years regardless of policy restrictions, potential for conflict between environmental flow protections and water security was evident in dry years. Therefore, strategies are particularly needed for drought‐year water management to ensure adequate environmental flows while reducing human water allocations in an equitable manner. Copyright © 2013 John Wiley & Sons, Ltd.     

黄河泥沙对氮迁移转化的影响及环境效应

黄河具有高泥沙含量的特点,泥沙对营养元素和污染物的迁移转化具有重要的影响。含氮化合物是我国河流的主要污染物之一,是国家重点防控污染物,是影响河流水体健康的重要因素。本文基于实验室模拟实验和野外采样研究成果系统综述了泥沙对河流氮迁移转化的影响及其环境效应。重点分析了(1)黄河水体含氮化合物的时空分布特征及来源;(2)含氮化合物的悬浮泥沙-水界面过程以及悬浮泥沙对氮转化过程的促进作用;(3)悬浮泥沙含量和粒径等对有机氮降解、硝化作用、反硝化作用、耦合硝化反硝化作用以及厌氧氨氧化作用的影响;(4)泥沙对温室气体N_2O产生和排放的影响,以及(5)水沙条件变异对氮迁移转化作用的影响。研究结果可为气候变化和人类活动双重作用下河流氮污染治理以及温室气体的排放控制提供科学依据。     

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.     

Life cycle assessment of an intensive sewage treatment plant in Barcelona (Spain) with focus on energy aspects

Life Cycle Assessment was used to evaluate environmental impacts associated to a full-scale wastewater treatment plant (WWTP) in Barcelona Metropolitan Area, with a treatment capacity of 2 million population equivalent, focussing on energy aspects and resources consumption. The wastewater line includes conventional pre-treatment, primary settler, activated sludge with nitrogen removal, and tertiary treatment; and the sludge line consists of thickening, anaerobic digestion, cogeneration, dewatering and thermal drying. Real site data were preferably included in the inventory. Environmental impacts of the resulting impact categories were determined by the CLM 2 baseline method. According to the results, the combustion of natural gas in the cogeneration engine is responsible for the main impact on Climate Change and Depletion of Abiotic Resources, while the combustion of biogas in the cogeneration unit accounts for a minor part. The results suggest that the environmental performance of the WWTP would be enhanced by increasing biogas production through improved anaerobic digestion of sewage sludge.     

The creation of management systems for funding priorities in wastewater project in rural communities in the Islamic Republic of Iran

For sustainable development an integrated cost-effective approach focused on the goal of health and environmental protection is necessary. In Iran more than 22 million people live in rural communities. A little more than 92% of the rural population in Iran have access to safe drinking water supply, but only less than 0.2% have sanitary wastewater disposal system. Groundwater is the main resource of water supply in rural communities in Iran and contaminated or untreated groundwater can be the major reason for waterborne diseases outbreak and wastewater discharge is the main cause of groundwater contamination. In new strategy in Iran's wastewater company, the importance of wastewater treatment is equal to water treatment in rural communities and the main goal in this section is providing sanitary wastewater disposal system for 8% of rural areas until 2010 and 30% until 2020. One of the most important limitations for establishment of wastewater disposal system is the limitation of governmental funds. For this reason, a national program was performed for ranking of rural communities with the goal of improving the funding effectiveness in wastewater management in rural communities. Many important criteria were considered for determination of priorities, these criteria include: population, population density, water consumption and wastewater generation, wastes disposal systems at present, environmental and health risks, agricultural and industrial wastewater, social conditions specially public participation, investment simplicity and type of living (seasonal or permanent). For collection of information about rural community, according to the criteria, a questionnaire was designed with 40 quantified questions. Questionnaires completed for all rural areas with more than 400 people population (more than 77% of rural population of the country). Completed questionnaires were analyzed with specific software for ranking of villages according to above mentioned criteria. Right now the classification of villages is available in provinces of the country from environmental and health crisis and funding points of view and we know whereabouts have priority for establishment of wastewater installations.     

Is stormwater harvesting beneficial to urban waterway environmental flows?

Urbanization degrades the hydrology and water quality of waterways. Changes to flow regimes include increased frequency of surface runoff, increased peak flows and an increase in total runoff. At the same time, water use in many cities is approaching, and in some cases exceeding, sustainable limits. Stormwater harvesting has the potential to mitigate a number of these detrimental impacts. However, excessive harvesting of stormwater could also be detrimental to stream health. Therefore, a study was undertaken to test whether typical stormwater harvesting scenarios could meet the dual objectives of (i) supplying urban water requirements, and (ii) restoring the flow regime as close as possible to 'natural' (pre-developed). Melbourne and Brisbane, which have different climates, were used along with three land use scenarios (low, medium and high density). Modelling was undertaken for a range of flow and water quality indicators. The results show that using these typical harvesting scenarios helped to bring flow and water quality back towards their pre-developed levels. In some cases, however, harvesting resulted in an over-extraction of flow, demonstrating the need for optimizing the harvesting strategy to meet both supply and environmental flow objectives. The results show that urban stormwater harvesting is a potential strategy for achieving both water conservation and environmental flows.     

Tolerance to hydraulic and organic load fluctuations in constructed wetlands.

This paper describes a two-year performance evaluation of four different constructed wetland (CW) treatment systems designed by IRIDRA Srl, located in central Italy. All four CW systems were established to treat wastewater effluent from different tourist activities: (1) one single-stage CW for secondary treatment of domestic wastewater (30 p.e.) at a holiday farm site; (2) a hybrid compact system consisting of two stages, a horizontal flow (HF) system followed by a vertical flow (VF) system for the secondary treatment of effluent from a 140 p.e. tourist resort; (3) a single-stage vertical flow (VF) CW for a 100 p.e. mountain shelter; and (4) a pair of single-stage, HF CWs for the secondary treatment of segregated grey and black water produced by an 80 p.e. camping site. These tourism facilities are located in remote areas and share some common characteristics concerning their water management: they have high variability of water consumption and wastewater flow, depending on the season, weather and weekly regularities; they have no connection to a public sewer and most sites are located in a sensitive environment. Total suspended solids (TSS), chemical oxygen demand (COD), biochemical oxygen demand (BOD5), ammonium (N-NH4+), nitrate (N-NOx), total nitrogen (Ntot), total phosphorus (Ptot), total coliform (TC), faecal coliform (FC), E. coli removal efficiencies for all four CW systems are presented. The results from this study demonstrate the potential of CWs as a suitable technology for treating wastewater from tourism facilities in remote areas. A very efficient COD reduction (83-95%) and pathogen elimination (3-5 logs) have been achieved. Furthermore, the CWs are easily maintained, robust (not sensitive to peak flows), constructed with local materials, and operate with relatively low cost.     

Evaluation of the ReVAQ project to achieve safe use of wastewater sludge in agriculture.

The use of wastewater sludge on arable land in Sweden has been limited for some years due to the low quality, in some respects, of the sludge and to the reluctance of farmers and the food industry to use it. To improve the quality of the sludge, the ReVAQ project has been started, and it now involves seven municipal wastewater organisations. The goal of the project is to introduce a process in which the quality is successively improved by a series of actions taken by society. These actions include tracking and eliminating sources of heavy metals and other substances. As there are numerous sources of some of the substances, the work concentrates on the major sources. Another important activity is to provide information to the users of the wastewater system. The project is being evaluated by Urban Water AB. The results from the first two years indicate that it may be possible to reach the primary technical goal: to obtain a sludge quality that corresponds to that of household wastewater. The more ambitious goal of reaching a quality corresponding to that of WC water (the sum of urine and faeces) does not seem realistic without far-reaching changes in society. The organisations involved, which take the work seriously and are goal-oriented, have achieved measurable results in a short time. The work is also accepted and supported by the board members. More effort is needed, however, to inform the users about the system, and to [motivate them to] change their behaviour regarding matters such as the purchase of everyday products and the use of the toilet facilities.     

吉林市排污河底泥的污染状况及其生态风险评价

以吉林市排污河中底泥为主要研究对象,布置12个监测断面35个代表性采样点,采集并分析了河道内底泥样品中8种重金属及16种USEPA优先控制的多环芳烃的含量,并分别采用地质累积指数法(I_(geo))、潜在生态风险评价法(PERI)、沉积物质量基准法(SQGs)对排污河底泥中污染物进行了生态风险评价。结果表明,该排污河底泥中重金属及多环芳烃均不同程度超过松花江水系沉积物背景值,其中Hg、Pb、Cu、As、NAP、ANT超标倍数分别为87.5、10.2、6.18、5.90、115.6和228.5;I_(geo)显示Hg的生态风险最大,I_(geo)达到了5.82,而Cd和Ni的风险较小,这与PERI中Hg风险最大的结果一致;SQGs评价结果表明由重金属及多环芳烃引起的污染会产生生物毒性,且不利生物毒性将频繁发生;(3)以上结果说明,该排污河呈现以Hg为主要风险因子的重金属与多环芳烃复合污染现象,在今后应加强底泥监测和定期清淤,从而推动区域生态环境的治理与恢复。     

Occurrence and fate of organic pollutants in combined sewer systems and possible impacts on receiving waters.

Selected organic pollutants are classified based on an intensive literature survey. Two wastewater parameters (COD and ammonium) and six selected organic pollutants (polycyclic aromatic hydrocarbons (PAH), diethylhexylphthalate (DEHP), estradiol (E2), ethinylestradiol (EE2), ethylenediamine tetraacetic acid (EDTA) and nitrilo triaceticacid (NTA)) are specified. As a result, for the first time representative concentrations in dry weather flow, surface runoff and effluent of wastewater treatment plants (WWTPs) in combined sewer systems (CSS) are stated. The second part of the paper presents a first estimation of main emission out of a combined sewer system and possible receiving water impacts in terms of (1) annual discharged loads calculated by pollution load simulations in a hypothetical catchment and (2) concentrations calculated in combined sewer overflows (CSO) discharges and resulting receiving water concentrations.     

Ecological perspectives on regulation and water allocation for the Ord River,Western Australia

Water management agencies throughout Australia are attempting to find a balance between the water requirements of ecological and socio‐economic environments as part of a holistic approach to managing flow‐dependent river ecosystems. Environmental water provisions are under consideration for the Ord River in far northern Western Australia. This river has been regulated for irrigation and there are plans for substantial expansion. Like other semi‐arid and tropical rivers, however, the hydrology of the Ord River is highly variable and unpredictable, and therefore, proportionate water release strategies for the environment that are based on average monthly flows are unsuitable. Regulation continues to produce pronounced ecological changes throughout the river system as the impacts of flow regime are negated. There is a dichotomy in optimal flow regimes for the contrasting management aspirations of ecological restoration based on low seasonal flows, and the dilution flows required for the drainage of agricultural effluent. Whilst current agricultural land and water management practices continue, the two cannot coincide, and consequently, a decision should be made regarding which environmental water allocation holds the primary value. Such a decision would guide the appropriate dry season flow regime on the lower Ord River. Copyright © 2002 John Wiley & Sons, Ltd.