Urban Wastewater Reuse Research Articles

Assessment of soil and groundwater impacts by treated urban wastewater reuse. A case study: Application in a golf course (Girona, Spain)

Starting in July 2000, treated wastewater of urban origin has been used for the "Serres de Pals" golf course irrigation (Girona, Spain). To evaluate if the soil and the aquifer underneath are affected by the utilization of this type of water, samples have been taken along a period of several months from the wastewater treatment plant, the stabilization lagoon, groundwater and soil profiles. Analyses have been performed for total coliforms and aerobic bacteria, soil water pressure and soil water content as well as chemical analyses of the irrigation water, aquifer and water of the vadose zone. Soil profiles taken at several times during the study indicate the absence of coliforms except for a short period during summer. In the vadose zone an increase of more than 1000 mg kg(-1) of NaO(2) in the top 60 cm of soil was observed while Cl(-) concentration in the aquifer reached up to 1200 mg l(-1) ten months after starting the irrigation.

Urban wastewater reuse: a pilot plant experience

The results of a preliminary verification of domestic wastewater reusability in L'Aquila (Italy) are reported. A Tertiary Treatment Pilot Plant (TTPP), rotary filtration and Ultraviolet Radiation (UV) disinfection, was added to an Urban WasteWater Treatment Plant (UWWTP) to test the compliance with water quality indicated for reuse by the enforced Italian regulation. The TTPP was managed varying UV dosages to evaluate disinfection effectiveness. A comparative analysis on two different disinfection systems, UV radiation and chlorination, was carried out. Moreover, a preliminary investigation to detect the presence of antibiotic-resistant bacteria and their sensitivity to the different disinfection systems was carried out.

Centralised urban wastewater reuse: what is the public attitude?

Public support is crucial for successful implementation of wastewater reuse projects. This paper analyses the findings of a questionnaire-type survey (256 participants) conducted to determine the attitude of Israeli urban public towards possible urban reuse options. The paper summarises the support/objection to 13 reuse options and the correlation between support and environmental awareness and perceptions. Results show that a high proportion of the participants supported options perceived as low-contact, such as irrigation of public parks (96%), sidewalk landscaping (95%) and use in the construction industry (94%), while higher-contact reuse options found less support (e.g. commercial launderettes, 60%). No correlation was found between biographical characteristics and support (education, gender, income, age). Based on the results, public campaigns in Israel should focus on disseminating information regarding wastewater treatment technologies, discuss health related issues, highlight the positive economic impact of water reuse and generate a positive public opinion, as these factors tend to influence individuals to support reuse projects.

A recycled water strategy for regional urban communities

The efficient use of water to meet the social, economic and environmental needs of our communities is becoming a consistent theme throughout much of Australia. This is particularly important for the Grampians Wimmera Mallee Water (GWMWater) region, especially given the extremely dry period currently being experienced. One of the options attracting the interest of government, community and industry as an accepted alternative to the finite limited fresh water supplies, is the use of recycled water, or treated wastewater. For over 30 years GWMWater has led the Victorian Water industry in recycled water use, with now over 92% reuse of urban wastewater now used within the region. GWMWater supplies over 30 customers with recycled water and has developed a process that assesses the technical, environmental, economic and social aspects of recycled water initiatives. A recycled water strategy has been development based on sustainability (Triple Bottom Line) principles and seeks to balance the development needs for water with emerging environmental imperatives [1]. To strengthen the process, GWMWater engages the community and stakeholders in the assessment and decision-making process, resulting in improved understanding of recycled water use viability issues and management requirements.

Urban wastewater treatment plants and reuse potential in Turkey: selected examples from the western cities

The present study refers to the outcomes of a detailed survey on the current situation of Turkish Urban Wastewater Treatment Plants (UWWTPs). The survey covers the identification of the population served by UWWTPs, presentation of the current technologies (physical, biological and advanced) applied in the country's UWWTPs, prevailing effluent disposal criteria, detailed assessment of UWWTPs selected from the Western part of Turkey representing highly urbanised and industrialised districts, and elucidation of needs for upgrading the selected UWWTPs to comply with the current discharge standards and irrigation water quality criteria. Following an extensive data collection and evaluation step, Turkey's most recent situation in the number of UWWTPs, effluent produced in Turkish municipalities both quantity-and quality-wise, urban wastewater treatment types and disposal methods as well as reuse potential of treated urban wastewater have been presented and discussed.

Assessment of the health hazards associated with wastewater reuse: Transmission of geohelminthic infections (Marrakech, Morocco)

To address the problem of water scarcity, wastewater has long been used for agricultural purposes in Marrakech (Morocco) and its benefits have long been recognized. However, the benefits of urban wastewater reuse may be limited by its potential health hazards associated essentially to the danger of transmission of pathogenic organisms to human beings. The current study aimed to evaluate the risks associated with raw wastewater reuse for agricultural purposes, and the incidence of geohelminthic infections among the children of the wastewater spreading area of Marrakech as compared to a control group. Faecal samples from 610 individuals were examined for Ascaris spp. ova and Trichuris spp. ova (323 children for the exposed group and 287 for the control group). The study duration was two months and a half, and was carried out in the summer period. A questionnaire-interview with children and parents was used to collect data on possible demographic, hygiene and behavioural-contact factors such as gender, age, family size, source of water supply, parental occupation. The investigations resulted in the detection of Ascaris spp. ova in 43 samples indicating a point-prevalence of 13.3% in the exposed group versus 1.7% for the control group. Trichuris spp. ova was detected in 43 faecal samples indicating a point-prevalence of 13.3% in the exposed group, and 3.8% in the control group. The Chi-square test showed that the differences observed between the exposed and control group are statistically significant (p < 0.01). Males are more infected with ascariasis and trichuriasis than females and children of 2 – 8 years of age are heavily infected as compared to 9 – 14-year-old children. Based upon the findings of this study, it is concluded that wastewater reuse for agricultural purposes presents an increased risk of infection in the exposed group.

Economic valuation of water and willingness to pay analysis in tropical fruit production in South-Eastern Spain

This paper reports a survey of how 64 tropical fruit growers from the Granada coast of Spain use and value their water resources. This area produces crops of high added value. The agricultural demand for water is ever increasing and is much greater than the actual supply. This problem is worsened by the infiltration of seawater into the aquifers that provide most of the irrigation water for the area. Moreover, the population increases five-fold in the summer due to tourism, further aggravating the problem of water scarcity. Technical innovations, especially the reuse of urban wastewater, and economic solutions, namely increasing the price of water, have been proposed under the European Union Water Framework Directive. The main questions in the survey are described and the responses analysed. The productive, technological and resource management characteristics that determine the growers’ expressed willingness to pay for the water they use, as well as their attitude towards the use of alternative sources (such as residual water) are examined. Finally, the marginal product value of irrigation water in the area is calculated.

Mathematical model for describing reactions of residual chlorine with organic matter in reclaimed wastewater

Among several applications of urban wastewater reuse, use of reclaimed wastewater to sustain stream flows has become attractive in the urban area. Since these rivers are used for recreational purposes and for restoring aquatic eco-system, the adequate control of residual chlorine is essential. Mathematical model for describing reactions between residual chlorine and organic matter in reclaimed wastewater has been developed. The model considers the effect of molecular weight distribution of organic matter on the reaction rate. Lab-scale experiments were performed to estimate reaction rates constants and to examine their temperature dependency. The experiments showed that 1) the smaller organic matter gave the larger reaction rate; 2) temperature effect on reaction rate was described by the Arrhenius formula; 3) decline of free chlorine had more temperature dependency than combined chlorine. The comparison of computed results with data from lab-scale experiments confirmed the validity of the model. We used the one-dimensional dispersion model with proposed reaction model and examined the seasonal variation of residual chlorine profile along the river sustained by reclaimed wastewater in Sapporo. Simulation showed that seasonal variation of nitrification performance in secondary treatment as well as change in temperature caused seasonal variation in residual chlorine profile along the river.

Methodological approach for evaluating the response of soil hydrological behavior to irrigation with treated municipal wastewater

This paper aims mainly to provide experimental evidence of the consequences of urban wastewater reuse in irrigation practices on the hydrological behavior of soils. The effects on both the hydraulic and dispersive properties of representative soils in southern Sardinia are illustrated. Ten undisturbed soil monoliths, 120 cm in height and 40 cm in diameter, were collected from plots previously selected through a soil survey. Soil hydraulic and solute transport properties were determined before and after application of wastewater using transient water infiltration and steady state-solute transport column experiments. Detailed spatial–temporal information on the propagation of water and solute through the soil profiles were obtained by monitoring soil water contents, θ, pressure heads, h, and solute concentrations, C, measured by a network of time domain reflectometry probes, tensiometers and solution samplers horizontally inserted in each column at different depths. A disturbed layer at the soil surface, which expands in depth with time, was observed, characterized by reduced soil porosity, translation of pore size distribution towards narrower pores and consequent decrease in water retention, hydraulic conductivity and hydrodynamic dispersion. It is shown that these changes occurring in the disturbed soil layer, although local by nature, affect the hydrological behavior of the whole soil profile. Due to the disturbed layer formation, the soil beneath never saturates. Such behavior has important consequences on the solute transport in soils, as unsaturated conditions mean higher residence times of solutes, even of those normally characterized by considerable mobility (e.g. boron), which may accumulate along the profile. The results mainly provide experimental evidence that knowledge of the chemical and microbiological composition of the water is not sufficient to evaluate its suitability for irrigation. Other factors, mainly soil physical and hydrological characteristics, should be considered in order to define appropriate guidelines for wastewater management.

STRATEGIC ENVIRONMENTAL ASSESSMENT (SEA) OF WASTEWATER REUSE POLICY: A CASE STUDY FROM TIANJIN IN CHINA

China is one of the thirteen countries in the world that lacks water. Rapid economic growth and urbanisation over the past two decades have exerted enormous pressure on China's water resources. The shortage of water resources and serious water pollution have become important factors restraining the sustainable development in the cities. Wastewater reuse has been proven to prevent water pollution and ameliorate the pressure on the water environment. Moreover, wastewater reuse can make up for the lack of funds in wastewater treatment. So, wastewater reuse is a viable choice to realise the sustainable utilisation of water resource in China. There still remain many uncertainties in wastewater reuse. It is strongly recommended that a wastewater reuse policy be pushed forward considering the necessity and the implications to society, the economy and the environment. Strategic environmental assessment (SEA) is seen as an important tool for integrating the environmental factors into decision-making. This paper illustrates a case study for SEA — aimed at Tianjin Wastewater Reuse Policy (TWRP). The process of SEA at the policy level and the related problems are presented within this case study. It provides a good framework for carrying out SEA of waste reuse at the national level. The study will support the Chinese Government in developing a national strategy on urban wastewater reuse through an investigation of the existing situations, evaluation of policy options in different areas, and offering recommendations.

Urban Wastewater Effects on Water Flow and Solute Transport in Soils

This article aims mainly to verify the consequences of urban wastewater reuse in irrigation practices on hydrological behavior of soils. Herein the effects on both the hydraulic and dispersive properties of characteristic soils in South Sardinia are illustrated. The study was carried out at the Ente Autonomo del Flumendosa (EAF) laboratory. Ten undisturbed soil monoliths, 120 cm height and 40 cm diameter, were collected from plots, the locations of which were preliminarily individuated through a prior pedological study. An experimental facility was set up and sensors for monitoring both soil water and solute concentrations were inserted horizontally in each column at different depths. A disturbed layer at the soil surface, which expands in depth with time, was observed, characterized by reduced soil porosity, translation of pore size distribution towards narrower pores and consequent drastic decrease of permeability. It will be shown that these changes occurring in the disturbed soil layer, although local by nature, affect the mean hydrological behavior of the whole soil profile.

Decline of residual chlorine in artificial stream flow sustained by reclaimed wastewater: field study in Sapporo

Among several applications of urban wastewater reuse, use of reclaimed wastewater to sustain stream flows has become attractive especially in urban areas. This environmental application of reclaimed wastewater occupies about 32% of total wastewater reuse in Japan. In this paper, residual chlorine in the full-scale project for environmental application in Sapporo was discussed. The field survey of residual chlorine showed that there was the hourly variation of residual chlorine concentration in the river and this variation depended on the hourly variation in composition of chlorine species in the effluent of the WWTP, and that the rate of decline of residual chlorine in the open channel section was greater than that in the pipe flow section. The simple mathematical model was developed for describing the decline process on the basis of the dispersion model including two reactions: interaction of residual chlorine and organic matter in reclaimed water and interaction of chlorine and pipe surface or bio-film. The expressions for these two reaction rates were obtained by lab-scale experiments and these calibration results showed that consumption rate of residual chlorine in the aqueous phase was comparable to the rate on the pipe wall in the pipe flow section, and that residual chlorine in the open channel was consumed mainly by bio-film. The calibrated mathematical model yielded a good estimation of the chlorine concentration profile.

Reuse of urban wastewater treated by a combined stabilisation pond system in Benslimane (Morocco)

The aim of this paper is to study the performance of a combined waste stabilisation pond after three years of functioning and the reuse of treated wastewater for irrigating potatoes and lettuce culture. The combined ponds showed good functioning conditions and excellent performances either for organic load (90%), faecal coliform (6 log units) or helminth eggs (100%) and produced a high and perennial effluent quality. The effluent could be used for non-restrictive irrigation, with a clear improvement of culture production and hygienic quality for both fruits and soil.

Health effect of urban wastewater reuse in a peri‐urban area in Morocco

Describes a study designed to assess the health effect of the agricultural reuse of urban wastewater in a peri‐urban area of Marrakesh, by evaluating the impact of this practice on the transmission of two pathogenic protozoan infections – giardiasis and amoebiasis. The study was carried out on two child populations (608 individuals). The exposed group (321 children) came from the wastewater spreading area, while the non‐exposed group (287 children) came from a control peri‐urban area where surface water is used in irrigation. Results showed that, of the exposed group, 67 per cent of the examined persons were infected by giardiasis and/or amoebiasis, versus 26 per cent in the control zone. Concludes that the risk of infection rate attributable to reuse of waste water is about 41 per cent. This excess of parasitic infestation in the spreading zone may be related to wastewater reuse in agriculture, which creates a polluted environment.

Wastewater reclamation and reuse in Japan: overview and implementation examples

To alleviate potentially catastrophic water supply and wastewater disposal problems as well as expand dependable water supply infrastructure, Japan has launched comprehensive urban wastewater reclamation and reuse projects since 1968. In this paper, the status of national policies on wastewater treatment, wastewater reuse characteristics, and some wastewater reuse experiences are presented. Two implementation examples in Tokyo and Fukuoka are discussed in detail, with special reference to application for toilet-flushing in high-rise business buildings and stream restoration and flow augmentation. It was found that the key to the success of wastewater reclamation and reuse is the quality of reclaimed water; public acceptance is closely associated with water quality and water supply dependability.

Wastewater reclamation and reuse in Japan: Overview and implementation examples

To alleviate potentially catastrophic water supply and wastewater disposal problems as well as expand dependable water supply infrastructure, Japan has launched comprehensive urban wastewater reclamation and reuse projects since 1968. In this paper, the status of national policies on wastewater treatment, wastewater reuse characteristics, and some wastewater reuse experiences are presented. Two implementation examples in Tokyo and Fukuoka are discussed in detail, with special reference to application for toilet-flushing in high-rise business buildings and stream restoration and flow augmentation. It was found that the key to the success of wastewater reclamation and reuse is the quality of reclaimed water; public acceptance is closely associated with water quality and water supply dependability.