Wastewater Management Systems Research Articles

Microbiological effluent control by UV-disinfection of a small-scale SBR system

Abstract Decentralized wastewater management systems, with the wastewater treated close to where it is generated, are considered by various researchers as an alternative to the traditional centralized system. The wastewater treatment facility should produce an effluent which is hygienically safe and can subsequently be utilized for watering lawns and irrigation. This article presents the operational data of such a small system and also presents disinfection efficiency data using a low-pressure UV lamp. To evaluate the SBR performance, several effluent parameters, such as BOD 5 , COD t and SS eff were measured and compared with the influent. The removal efficiencies were 90.9% for BOD 5 , 86.9% for COD t and 93.9% for SS eff (average values). Disinfection efficiency was evaluated through measurement of the controlled encountering coliform bacteria (total coliforms (TC) and faecal coliforms (FC) before and after the UV lamp), because of the central role they play in discharge permits. To overcome disinfection problems that result from the influence of particle-associated organisms, a Mean Cell Retention Time (MCRT) of 20 d was used, in combination with a well-designed clarification phase. A clear reduction of the coliform bacteria concentration was observed, which followed a similar pattern of the reduction of the SS eff . The Pearson correlation coefficient was used to express the degree of linear relationship between the TC and SS eff and FC and SS eff parameters.

Satellite Systems for Enhanced Wastewater Management in Urban Areas

Wastewater management systems are under pressure due to changing economic and environmental conditions. For example, severe water shortages are being experienced in a number of metropolitan areas due to the combined effects of climate change, continued population growth, and over drafting of water supplies. Drought conditions have resulted in rationing of remaining water supplies, conflicts between environmental and agricultural uses of water, increases in the value of water, and restrictions on irrigation and domestic use in urban locations. Many locations throughout the world are expected to experience more frequent and extreme drought conditions in the near future. It is clear that more effective utilization must be made of existing water supplies, especially in urban areas.

Domestic wastewater management in South and Southeast Asia: the potential benefits of a decentralised approach

Owing to its enormous construction and maintenance costs, the management of wastewater in many urban centres of developing countries via a centralised wastewater management approach is very difficult. Often, untreated wastewater is directly discharged into adjacent natural water courses, causing a grave threat to both public health and the aquatic environment. A decentralised wastewater management approach is a prospective solution to overcome this adverse situation because of its low cost, simple operation and revenue return. To identify the potential of a decentralised wastewater management system in developing countries, the wastewater management policies, institutional frameworks, reuse practices and sanitation situations in selected Asian countries were reviewed and recommendations for effective wastewater management are proposed.

Perception of House Onsite Grey Water Treatment and Reuse in Palestinian Rural Areas

House onsite treatment of grey water and reuse of treated effluent for irrigating crops are increasingly accepted and practiced in Palestinian rural developments as more than 600 units are operational. The main goal of this research was to assess the impact of those systems on the environment, health, and the Palestinian society and economy through field survey in Qebia village where 47 house onsite sanitation systems were recently implemented. The results revealed that the biggest incentive for applying this system is the reuse of treated grey water for irrigation purposes, which is socially accepted. The application of those systems is currently limited and tied to the availability of external funds. The main concerns people have over the constructing of those house onsite systems are health risks, flooding, and odour emission. Accordingly, the concept of house onsite wastewater management systems is very promising, but provision of proper technical solutions is very important.

Comparison of Environmental Effects and Resource Consumption for Different Wastewater and Organic Waste Management Systems in a New City Area in Sweden

An analysis of the environmental effects and resource consumption by four systems for management of wastewater and organic household waste in a new city area have been performed, as follows: (1) conventional system complemented with advanced sludge treatment for phosphorus recovery, (2) blackwater system with urine diversion and food waste disposers, (3) blackwater system with food waste disposers and reverse osmosis, and (4) local wastewater treatment plant with nutrient recovery by using reverse osmosis. Substance-flow analysis and energy/exergy calculations were performed by using the software tool URWARE/ORWARE. Emissions were calculated and classified based on the impact categories global warming potential, acidification, and eutrophication, according to ISO 14042 (2000). The analysis also included nutrient recovery (i.e., the potential to use nutrients as a fertilizer). Depending on which aspects are prioritized, different systems can be considered to be the most advantageous.

The role of satellite and decentralized strategies in water resources management

Existing and projected water shortages and related factors have helped focus attention on the need for water reuse. With recent technological advances in wastewater treatment, it is now possible to produce reclaimed water of any quality. Thus, the use of reclaimed water will depend on the reuse opportunities and the cost of the required infrastructure. Historically, centralized wastewater treatment facilities have served the needs of organized societies since the mid 1800s. However, as there are limited options for expansion of most existing centralized facilities, the use of satellite and decentralized wastewater management systems offers significant advantages including being close both to the source of wastewater generation and to potential water reuse applications. The comparative advantages of satellite and decentralized wastewater management systems for a number of water reuse applications are presented and discussed in this paper. Selected case studies are presented to demonstrate the utility of satellite and decentralized wastewater management. Specific issues associated with the application of such systems in existing and in new developments are examined and discussed.

Factors influencing wastewater management performance: Case study of housing estates in suburban Bangkok, Thailand

As population densities have risen and settlements become increasingly crowded, wastewater effluent volumes have, not unexpectedly, also risen. The adverse impacts of effluent from housing estates (HEs) in suburban areas of Thailand, served by local wastewater management (WWM) systems, are of particular concern. Because of this problem, which reflects the poor performance of WWM systems, it has become increasingly important that the pivotal factors that hinder WWM improvements be identified and effective solutions be proposed and implemented. The goal of the research described in this paper was to determine the critical factors influencing WWM performance at HEs in suburban Bangkok, using multiple regression analysis. Three significant factors encompassing financial, social, institutional and general aspects were identified for each type of WWM system ( community centralized and onsite). For the community centralized system, the key factors were house price, type of organization managing the HE, and the attitudes of the organization. For onsite systems, the three factors were total number of house units, direct experience with water pollution and percentage of occupied houses. These findings reflect the importance of having a WWM that employs an integrated approach rather than focusing on specific aspects in isolation from other factors. WWM performance could be improved if significant factors indicating high priority concerns were to be identified and properly applied. Addressing the priority concerns could, consequently, contribute to the development of appropriate environmental management measures, plans, and policies related to HE WWM.

Technology selection and comparative performance of source-separating wastewater management systems in Sweden and The Netherlands

The research described in this paper has evaluated five demonstration projects with source-separating sanitation at neighbourhood scale, 10 years or more after their establishment. It presents the results of two systems with local grey water treatment in The Netherlands and three sites with urine separation in Sweden. The study has focused on (1) the drivers and barriers of the stakeholders that were responsible for project implementation and (2) the comparative performance of the source separation systems after their establishment. In The Netherlands the main drivers were water use reduction, combating sewer overflows and reduction of emissions. For the Swedish cases the main drivers of the involved actors were nutrient recycling, emission reduction and an active policy of the local government. The main barriers in all cases were higher investment costs and low experience with new sanitation approaches systems compared with the conventional system. Three of the sites showed a lower performance with respect to public health because effluent monitoring protocols for the grey water treatment systems were not in place or people could have direct contact with faeces. Lack of operation and maintenance is a cause of occasional failure for the grey water treatment systems, while the dominant failure reason for the urine separation systems was pipe clogging. The inventory showed that source-separating sanitation systems have a high potential to save or recover resources (water and nutrients).

Decentralized sanitation implementation in Vietnam: a peri-urban case study

This research presents one of the first comprehensive case studies of a small-scale wastewater management project in Vietnam. The research demonstrates how the community integrated a small-scale wastewater management system based on household participation and community management. It is argued that local resources of peri-urban and small towns could be used more efficiently to contribute to wastewater management in Vietnam if appropriate technologies are used and if their management and technical capacities are reinforced.

Flexibility analysis of chemical technology systems

Flexibility conditions are described for chemical technology systems (CTSs) for different cases of completeness of experimental data available at the CTS operation stage. Because of the max-min-max procedure, flexibility analysis presents a multiextremum, nondifferentiable optimization problem. The branch-and-bound and split-and-bound approaches are suggested for solving this problem. The flexibility analysis is illustrated by reference to a biological wastewater management system.

The road not taken: how traditional excreta and greywater management may point the way to a sustainable future

This paper argues that modern, end-of-pipe sanitation systems are not the pinnacle of centuries of wastewater technology development, and may actually prove to be a technological dead-end: expensive to build, operate and maintain, and out of step with traditional wastewater management philosophy. A brief examination of a series of excreta and wastewater management systems from around the world and throughout history clearly shows that viewing faeces, urine and grey water as a worthless waste to be disposed of is only a modern concept, which ignores the realities of limited resource availability, and the obvious benefits to be had from closed-loop systems – as was clearly recognised in the past. While currently, expensive, technically complicated end-of-pipe sanitation systems dominate, several modern systems have been developed specifically to ensure an efficient resource recovery and reuse. Reconsidering and researching historical approaches to wastewater management and applying modern technologies to improve their functionality may contribute to the solution of many of today's sanitation and environmental problems.

Contaminant Transport Model for Unsaturated Soil Using Fuzzy Approach

Contaminant transport in the unsaturated zone is important for managing water resources and assessing the damage due to contamination in the field of irrigation, water management, wastewater management, and urban and agricultural drainage systems. Deterministic modeling which is widely used for contaminant transport is not adequate because it considers model input parameters as well-defined crisp values and hence does not account for uncertainties and imprecision. This paper presents a contaminant transport model based on fuzzy set theory to simulate water flow and contaminant transport in the unsaturated soil zone under surface ponding condition. Among all soil hydraulic parameters that have uncertainty associated with them, saturated hydraulic conductivity was found to be the most sensitive to model outputs. Trapezoidal fuzzy numbers were used to express the uncertainties associated with saturated hydraulic conductivity. The incorporation of uncertainties into contaminant transport model is useful in decision making, as it yields scientifically and practically based estimates of contaminant concentration.

Reverse osmosis processing of organic model compounds and fermentation broths

Post-treatment of an anaerobic fermentation broth was evaluated using a 150 gal/day, single cartridge prototype reverse osmosis (RO) system. Baseline tests were conducted at 25 °C using six organic model compounds representing key species found in the fermentation broth: ethanol, butanol, acetic acid, oxalic acid, lactic acid, and butyric acid. Correlations of the rejection and recovery efficiencies for these organic species, individually and in simulated mixtures, were obtained as a function of feed pressure with and without recirculation of the retentate. The actual fermentation broth obtained from a continuous-flow biohydrogen process was treated by the RO system under the operating conditions similar to those used in the baseline tests, resulting in greater than 95% removal of total organic carbon. These results are encouraging and useful for further studies on the feasibility of incorporating the RO technology into an integrated and field deployable wastewater management and water recovery system.

Substance flow analysis of the wastewater collection and treatment system

The holistic approach to water resources management introduced by the EU Water Framework Directive (WFD) implies the adoption of methodologies that are suitable to reveal the major pressures and impacts on the receiving waters at river basin level in an effective and efficient way. This study investigated the general adequacy of substance flow analysis (SFA) for the analysis of urban wastewater systems (urban catchment, sewer, WWTP, receiving water). The paper provides a description of the approach and a useful demonstration of the method through the illustration of a case study. The study considered the fluxes of six substances going to, through and from the wastewater management system. The results suggest that the proposed methodology can be used for the identification of stressors on the receiving water bodies and highlights that the scale dependency of results in such studies is of primary importance.

On-site wastewater management system design and landslide risk assessment

On-site wastewater management system design and performance is significant in assessing landslide risk in areas with potential for slope instability. Much of the development in Pittwater, NSW, local government area is on steep coastal land which has a history of slope instability. Concern over cases of poorly performing or failing on-site wastewater systems and the recognition that these and newly designed systems could be contributory to slope instability has been a factor in Pittwater Council, NSW, requiring that landslide risk assessment be undertaken for new and amended on-site wastewater management systems in potentially unstable areas. This paper describes the wastewater management system design and landslide risk assessment undertaken at Pittwater Youth Hostel in accordance with the Australian Geomechanics Society's Geotechnical Risk Management procedure to comply with the Pittwater Policy. The work completed illustrates both necessary and effective interaction of the wastewater and geotechnical professions to achieve a successful outcome for the client. It is likely that this professional interaction will be increasingly common along the NSW coast and elsewhere.

Aspects of design, structure, performance and operation of reed beds – eight years' experience in northeastern New South Wales, Australia

Reed beds (horizontal subsurface flow constructed wetlands) have been employed as secondary treatment devices in on-site and decentralised wastewater management systems in the northeast of the Australian state of New South Wales (NSW) for over a decade. This paper summarises some of the practical and research findings that have come to light in that time. Experience with various aspects of reed bed structure is discussed. A study of the evaporative performance of four small beds planted with Phragmites australis yielded an annual crop factor of 2.6. A total of 28 studies on reed beds treating a variety of commonly encountered wastewater streams yielded the following mean pollutant removal efficiencies: total suspended solids (TSS) 83%, biochemical oxygen demand (BOD) 81%, total nitrogen (TN) 57%, total phosphorus (TP) 35% and faecal coliforms (FC) 1.9 logs. The reed bed is becoming the preferred on-site technology for removing TN and BOD and polishing TSS from primary settled domestic wastewater. Sizing beds for a residence time of approximately five days has become standard practice. A study of six reed beds found six different species of earthworm present, mainly Perionyx excavatus (Indian Blue). A mesocosm experiment subsequently showed that the worms were translocating clogging material from the substrate interstices to the surface of the bed thereby indicating a possible method for prolonging reed bed life.

The effect of nitrogen loading on on-site system design: a model for determining land application area size

Designers of on-site wastewater management systems have six opportunities to remove pollutants of concern from the aqueous waste stream before it reaches ground or surface waters. These opportunities occur at source, at point of collection (primary treatment), secondary treatment, tertiary treatment, land application and buffers. This paper presents a computer based model for the sizing of on-site system land application areas applicable to the Lismore area in Northern New South Wales, a region of high rainfall. Inputs to the model include daily climatic data, soil type, number of people loading the system and size of housing allotment. Constraints include allowable phosphorus export, nitrogen export and hydraulic percolation. In the Lismore area nitrogen is the nutrient of most concern. In areas close to environmentally sensitive waterways, and in dense developments, the allowable annual nitrogen export becomes the main factor determining the land application area size. The model offers system designers the opportunity to test various combinations of nitrogen attenuation strategies (source control, secondary treatment) in order to create a solution which offers an acceptable nitrogen export rate while meeting the client's household and financial needs. The model runs on an Excel spreadsheet and has been developed by Lismore City Council.

Project Addresses Wastewater Seepage in Florida Keys

This article reports on a new wastewater management system being built by the Haskell Company for the Key Largo, Florida, Wastewater Treatment District. The new system will help correct a long‐standing wastewater seepage problem throughout the Florida Keys and will use a sanitary sewer vacuum collection system that uses vacuum suction to deliver waste to the plant. It complies with the Florida Department of Environmental Protection wastewater treatment standards for 2010.

The effect of food waste disposers on municipal waste and wastewater management

This paper examines the feasibility of introducing food waste disposers as a waste minimization option within urban waste management schemes, taking the Greater Beirut Area (GBA) as a case study. For this purpose, the operational and economic impacts of food disposers on the solid waste and wastewater streams are assessed. The integration of food waste disposers can reduce the total solid waste to be managed by 12 to 43% under market penetration ranging between 25 and 75%, respectively. While the increase in domestic water consumption (for food grinding) and corresponding increase in wastewater flow rates are relatively insignificant, wastewater loadings increased by 17 to 62% (BOD) and 1.9 to 7.1% (SS). The net economic benefit of introducing food disposers into the waste and wastewater management systems constitutes 7.2 to 44.0% of the existing solid waste management cost under the various scenarios examined. Concerns about increased sludge generation persist and its potential environmental and economic implications may differ with location and therefore area-specific characteristics must be taken into consideration when contemplating the adoption of a strategy to integrate food waste disposers in the waste-wastewater management system.

Decentralized wastewater management in peri-urban areas in low-income countries

In peri-urban areas in low-income countries, conventional centralized approaches to wastewater management have generally failed to address the needs of communities for the collection and disposal of domestic wastewater and faecal sludges from on-site sanitation. There are opportunities for implementing wastewater management systems based on a decentralized approach that may offer opportunities for wastewater re-use and resource recovery as well as improvements in local environmental health conditions. Decentralized approaches may also offer increased opportunities for local stakeholder participation in planning and decision-making, and the paper emphasizes the importance of building the capacity of local organizations in all aspects of decentralized wastewater management. Using examples of functioning systems, the paper discusses the operational sustainability of decentralized technologies for wastewater management in peri-urban areas and their associated management requirements. The paper concludes that a concerted capacity-building effort is required to overcome the constraints that hinder the implementation and sustainability of decentralized wastewater systems, and proposes a framework for achieving this goal.