The main research question was how to optimize and sustain the overall benefits of wastewater irrigation in peri-urban areas in arid and semi-arid regions, including reduction of health and environmental risks associated with this practice

Objectives

• Improved understanding of wastewater irrigation, management systems, linkages and interactions with other water sub-sectors, together with impacts on income, health and environment;
• Assessment of the health and environmental risks involved in wastewater irrigation and quantification of their impacts;
• Developing tools and methodologies to quantify costs/benefits, enabling users and decision-makers to evaluate tradeoffs in different socioeconomic and cultural settings;
• Identifying and evaluating cost-effective technologies, support systems and management methods, and developing options to reduce tradeoffs between irrigation performance and health and environmental risks, and
• Assessing multi-institutional, user-inclusive, mechanisms for adoption of the recommended range of options.

Methods

• The research work conducted in Pakistan (2001-2003) consisted of several components, which together formed a holistic evaluation of wastewater use practices.
• Water and nutrient balance: Data collection was looking at fields irrigated with normal water, untreated and treated wastewater, as well as mixtures.
• Health survey: Vector-breeding: Wastewater bodies were sampled for mosquito larvae, with a specific focus on the wastewater stabilization ponds (WSP). A total of 3,359 collected samples yielded 682,731 Culex larvae of six species, and 125,142 anophelines representing eight species. The anaerobic treatment ponds were dominantly occupied by Culex mosquitoes. Facultative ponds favored the breeding of Anopheles and Culex mosquitoes.
• Health survey: Intestinal nematode and protozoa infections - Phase 1 of the study consisted of demographic data collection and a disease questionnaire. Stool samples of over 1,500 adults and children covering wastewater farmers, textile laborers and farmers using regular irrigation water were collected over the period of September 2002–April 2003 and analyzed for intestinal nematode infections, including hookworm and roundworm infections and intestinal protozoa infection, with a particular focus on Giardia intestinalis and Entamoeba histolytica, all of which have been associated in other studies with the use of wastewater.
• Heavy metal accumulation and plant up-take: Soil and wheat samples were collected from pre-selected fields at 1 km intervals along the length of Channel 4 (CH4) to evaluate the impact of wastewater utilization on soil heavy metal accumulation. As a control, samples were also collected from fields receiving regular irrigation water from the Dhudi Wala Minor.
• Nationwide survey: Survey covered 60 randomly selected cities in the four provinces of Pakistan. With the help of a standard questionnaire, field visits and interviews with farmers and sanitation officers a clear picture was obtained of the extent and characteristics of untreated wastewater irrigation in Pakistan.
• Socio-economic surveys: A desk study was conducted early in 2001 which resulted in two working papers by Hussain et al., setting out a framework for the analysis of the different cost, health, environmental and agronomic benefits and increased productivity, lower input cost, etc., of the use of wastewater.
• Wastewater treatment technologies: This research component was managed by the Technical University of Hamburg-Harburg with some inputs from the International Water Management Institute. A protocol was developed for self-sustained and cost effective treatment alternatives to offset some operational and investment costs for wastewater treatment. A combined wastewater treatment and duckweed-fish aquaculture project was proposed to the local Water and Sanitation Agency. This recommendation will be taken forward as a component of the current BMZ funded project.

COLLABORATORS

MAJOR DONORS

PROJECT DURATION

LOCATION