Document(s) 12 of 23 Blanca Jiménez, Duncan Mara, Richard Carr and François Brissaud1 This chapter summarizes the main characteristics of wastewater treatment processes, especially those suitable for use in developing countries, from the perspective of their potential to produce an effluent suitable for safe agricultural irrigation; it thus concentrates on pathogen removal and nutrient conservation. Wastewater treatment processes are divided into two principal categories: ‘natural’ systems which do not rely on the consumption of large amounts of electrical energy and which are therefore more suitable for use in developing countries; and conventional electromechanical systems which are wholly energy-dependent and which, if used in low income regions, require high levels of financial investment for their construction and skilled manpower for their successful operation and maintenance. PART 3. MINIMIZING HEALTH RISKS 8. Wastewater Treatment for Pathogen Removal and Nutrient Conservation: Suitable Systems for Use in Developing Countries: International Development Research Centre
Object moved Contamination of soil with helminth eggs in the samples of fields, kitchen gardens, yards and composts in rural areas of Lodz district (Poland) was investigated. In this study, helminth eggs were found in 60–100 % of field samples, in 20–100 % of yards samples, in 0–20 % of kitchen gardens samples and in 10–100 % of composts. The highest average density of helminth eggs in 100 g of soil was detected in composts (44.0), then fields (28.5) and yards (18.0). In samples taken from kitchen gardens the average density of eggs was 0.4/100/g of soil. The comparison of frequency of positive samples from fields, kitchen gardens and yards did not exhibit significant difference (p > 0.05). The soil samples of fields contained mainly eggs of Ascaris spp. (87.7 %), less frequently Toxocara spp. (7.7 %) and Trichuris spp. (3.5 %).
4.2.3 LagoonsPonding or lagooning is effective in treating wastewater and can reduce BOD and SS to the same levels as mechanical treatment plants (e.g. Activated Sludge Treatment). In addition because of the longer residence time of wastewater in the lagoon (days), removal of pathogenic bacteria and viruses by natural die-off is greater than in an activated sludge treatment plant (residence time usually several hours). Cysts of parasites and helminth eggs are also usually removed through sedimentation in the lagoons.A lagoon is a shallow excavation in the ground (1 to 2 m deep). Off-site wastewater treatment systems
Sewage treatment The objective of sewage treatment is to produce a disposable effluent without causing harm to the surrounding environment, and prevent pollution. Sewage treatment is the process of removing contaminants from wastewater and household sewage, both runoff (effluents), domestic, commercial and institutional. It includes physical, chemical, and biological processes to remove physical, chemical and biological contaminants. Its objective is to produce an environmentally safe fluid waste stream (or treated effluent) and a solid waste (or treated sludge) suitable for disposal or reuse (usually as farm fertilizer). Using advanced technology it is now possible to re-use sewage effluent for drinking water, although Singapore is the only country to implement such technology on a production scale in its production of NEWater. History
What constitutes a perfectly satisfactory water supply to some consumers leaves others, even in developing countries, considering themselves unserved. In much of rural Africa, a hand pump 500 meters from the household is a luxury, but most residents in urban Latin America would not consider themselves served by a water supply unless they had a house connection. In Asia, urban planners would consider a community served if there were sufficient standposts on the street corner; however, if the water only flows for a few hours per week, producing lengthy nighttime queues, the residents may regard this situation as a lack of service and opt to buy water expensively from itinerant vendors. As these examples illustrate, water supply is not a single, well-defined intervention, such as immunization, but can be provided at various levels of service with varying benefits and differing costs. Levels of Service and Their Costs Water Supply, Sanitation, and Hygiene Promotion - Disease Control Priorities in Developing Countries - NCBI Bookshelf
Chapter 2 - Health risks associated with wastewater use Types of pathogens present in wastewater Pathogens that reach the field or crop Pathogen survival under agricultural field conditions Relative health risk from wastewater use Agronomic conditions that minimize disease spread when wastewater is used for irrigation Guidelines for public health protection during wastewater use There are agronomic and economic benefits of wastewater use in agriculture. Irrigation with wastewater can increase the available water supply or release better quality supplies for alternative uses. In addition to these direct economic benefits that conserve natural resources, the fertilizer value of many wastewaters is important. FAO (1992) estimated that typical wastewater effluent from domestic sources could supply all of the nitrogen and much of the phosphorus and potassium that are normally required for agricultural crop production. In addition, micronutrients and organic matter also provide additional benefits.