Wastewater Use In Agriculture Research Articles

Influence of urban wastewater on stream water quality and agriculture in and around Kumasi, Ghana

This paper presents some findings from an ongoing International Water Management Institute research project in Ghana on urban wastewater use in agriculture. The paper focuses on the influence of urban wastewater on stream water quality and peri urban agriculture in Kumasi, and aims to develop strategies to reduce environmental pollution and risks from agricultural use of wastewater. It drew on interviews with local authorities, sanitation services providers, vegetable producers, traders and consumers, and on an assessment of the existing sanitation infrastructure and water quality. With few industries in Kumasi, urban wastewater is generated mostly from domestic sources. Population increase and lack of investment have overstretched the few available sanitation facilities, and large volumes of untreated or partially treated wastewater end up in nearby streams. High levels of faecal coliform were recorded in the city and downstream, as well as on vegetables in Kumasi’s markets, as contaminated wastewater streams are used for irrigation. Although urban and peri urban agriculture has a positive impact on food supply and livelihoods, it poses health risks for farmers and consumers. The paper discusses the constraints on addressing these problems and makes some recommendations regarding low-cost strategies for safer use of available water, better urban decentralized wastewater management and increased public awareness.

Partial characterization of the polluting load of swine wastewater treated with an integrated biodigestion system

The stabilization of swine wastewaters from swine confined housing by the combination of a upflow anaerobic sludge blanket (UASB) reactor and waste stabilization ponds is a viable alternative to minimize the environmental impact caused by inadequate disposal of swine wastewaters. In the present study, the polluting load of pre-decanted swine wastewater treated with a series of two 0.705 m 3 UASB reactors and then in parallel in aerated and non-aerated stabilization tanks was investigated from January to July, 2000. Physicochemical and microbiological analyses were made adopting standard methods (Standard Methods for Examination of Water and Wastewater, 19th ed., American Public Health Association, Washington, DC, 1995). COD values decreased as the wastewater ran through the integrated biodigestion system dropping from about 3492 ± 511–4094 mg l −1 ± 481 to 124 ± 52–490 mg l −1 ± 230, while nitrate and nitrite levels increased in stabilization tanks, ranging respectively from 4 ± 0 to 20 mg l −1 ± 3 and 3 ± 1 to 11 mg l −1 ± 24. Although the removal of Escherichia coli was more than 97% ± 6, the effluents of the treatment system still contained unacceptable levels of E. coli (1.6 × 10 3–1.2 × 10 6 100 ml −1) according to WHO guidelines for use of wastewater in agriculture and aquaculture. These results indicate the necessity of changes on operational characteristics of the treatment system such as an increase of the hydraulic retention time in UASB reactors or in stabilization tanks.

Domestic wastewater treatment in waste stabilization ponds for irrigation in Mendoza, Argentina: policies and challenges

Arid areas call for imaginative water management solutions to avoid the dangers of water shortages. Growing demands of water for domestic and industrial uses decrease the availability of water for agriculture. It therefore becomes necessary to set up a policy for the use of domestic effluents. For the province of Mendoza, Argentina, with 1,500,000 inhabitants, a master plan was designed as of 1991 for the treatment of domestic effluents and subsequent disposal for irrigation. The guidelines set up by WHO for the use of wastewater in agricultural applications were taken into consideration. At present, the Province of Mendoza has available projects which are either complete, in execution or in the bidding process, entailing secondary treatment capacity with reuse of 320,000 cubic metres/day and an estimated possible irrigation area of 10,000 hectares. With this infrastructure, some strategic lines of action are recommended to establish a policy for the agricultural use of wastewater: (a) to program the use of treated wastewater to avoid discharges to irrigation flows; (b) to develop an institutional scheme for the efficient and safe use of these waters; and (c) develop scientific and technologic know-how to accompany the updated policies.

Health risk assessment due to wastewater use in agriculture

Abstract

Performance assessment of a wastewater treatment plant producing effluent for irrigation in Egypt

A conventional activated sludge treatment facility was the subject of this study. The assessment was directed at determining the characteristics of the raw wastewater, the quality of the treated effluent and the efficiency of the various treatment units. Furthermore, the water quality along the effluent irrigation canal was monitored. The assessment of the quality of the treated effluent for irrigation is based on the guidelines established by the World Health Organization and the Egyptian decree 9/89 for the use of wastewater in agriculture. The results of the study indicated that the concentration of the raw wastewater was considered moderate. The mean values of the COD (Chemical Oxygen Demand), BOD (Biological Oxygen Demand) and total suspended solids (TSS) were around 250, 102 and 142 mg l−1, respectively. This was attributed to the high quantities of wastewater from industrial sources. The overall efficiency of the treatment facility was good. The mean residual COD, BOD and TSS were 25, 8 and 21 mg l−1 and the corresponding percentage removal values were 90, 92 and 85%, respectively. The maximum percentage removal of oil and grease was 84% with a mean residual concentration of 24 mg l−1. The total viable count (22°C and 37°C), faecal coliform and aecal streptococci were reduced by 99.9% compared to only 99.5% for Salmonella. Bacteriological examination of the dried sludge indicated a reduction of nine logs of faecal coliform and faecal streptococci, as compared to thickened sludge. Analysis of the Ni, Cu, Pb and Cr in the dried sludge indicated that their concentrations are within the permissible limits. Zinc exceeded the consent standards by 50%. The results of the analyses of samples collected at the beginning of the irrigation canal indicated insignificant changes from the characteristics of the final effluent. Samples collected at a distance of 2km along the irrigation canal showed mean reductions in the COD and BOD of 28.6 and 47%, respectively, which could be attributed to sedimentation and/or a self-purification effect. An increase in the total nitrogen, total phosphorus and total viable count was also recorded, which could be due to seepage from the agricultural land. From the data available it is evident that the treated wastewater could be used for restricted irrigation. The design and implementation of a monitoring programme is recommended.

The Urban Water Cycle, including Wastewater Use in Agriculture

Urban wastewater is an exploitable water resource in water-short countries and its controlled use in agriculture will make contributions to water conservation and food production. Health risks must be understood and appropriate control measures must be introduced into effluent use schemes. Recent guidelines from the World Health and Food and Agriculture Organizations of the UN now provide authoritative advice on health control and agricultural issues. Among the measures which can be considered are wastewater treatment, restricted crop selection, careful choice of irrigation method, adoption of appropriate farm management practices, human exposure control and promotion of hygiene. The approach adopted must be consistent with local socio-cultural, environmental and institutional factors and thoroughly planned as an integrated programme of wastewater disposal and food production.

Book Reviews

Book Reviews in This Article:Health Guidelines for the Use of Wastewater in Agriculture and Aquaculture.Corrosion Management in Water Supply Systems, by W. Harry Smith.Long Sea Outfalls. Proceedings of an ICE Conference held in Glasgow 19–21 October 1988. Published by Thomas TelfordThe Smeatonians, A History of the Society of Civil Engineers, by J. G. Watson.Treatment of Sewage Sludge, edited by A. M. Bruce, F. Colin and P. J. Newman. Published by Elsevier

Problems of Using Wastewater on Vegetable Crops

Abstract If wastewater is to be recycled safely for agricultural production the problems associated with using it on vegetables need to be known. The objective of this review is to determine those problems. Several earlier reviews dealing with the use of wastewater in agriculture have been published (5, 7, 9, 19, 27, 30, 31, 42). Raw wastewater, or primary effluent, is not considered in this paper because secondary effluent is the type of wastewater generally used for irrigation in the United States (42). Primary treatment involves only settling tanks, from which anything in the raw sewage that can float or sink is removed. Sewage from primary treatment is subjected in secondary treatment to the action of living microorganisms: e.g., activated-sludge processes, trickling filters, treatment ponds (42). Also, this paper is limited in discussion to municipal waste-water and does not mention wastewater from industry, including wastewater from vegetable-processing plants. This review is divided into 3 areas: physical, chemical, and biological problems.

High levels of microbial contamination of vegetables irrigated with wastewater by the drip method

The public health aspects of the use of wastewater in agriculture and the effects of the drip irrigation method on the contamination of vegetables were studied. The method used was to simulate enteric microorganisms' dissemination by contaminated irrigation water in the field. The vegetables were irrigated with an effluent inoculated with a high titer of traceable microorganisms: poliovirus vaccine and a drug-resistant Escherichia coli. The dissemination of the marker organisms in the field was followed, and the effects of certain manipulations of the drip irrigation method on the contamination of the crops by the effluent were examined. It was shown that drip irrigation under plastic sheet cover with the drip lines placed either on the soil surface or buried at a depth of 10 cm significantly reduced crop contamination from inoculated irrigation water even when massive doses of bacteria and viruses were used. The microbial contamination was found to persist in the irrigation pipes and in the soil for at least 8 and 18 days, respectively. The data indicate that the recovery of the marker organisms was affected by soil texture and environmental conditions.