Journal of Basic and Applied Engineering Research Print ISSN: 2350-0077; Online ISSN: 2350-0255; Volume 1, Number 9; October, 2014 pp. 98-104 © Krishi Sanskriti Publications http://www.krishisanskriti.org/jbaer.html Effect of Natural Coagulants on Solar Water Disinfection Sonal Choubey Disha Institute of Management and Technology, Satya Vihar, Raipur Abstract: Solar water disinfection is the process of treating microbiologically contaminated water in clear plastic bottles through exposure to sunlight. One of the major limiting factors of this treatment is source water quality. This work investigates the impact of source water turbidity on solar disinfection efficiency and evaluates a natural coagulant for turbidity removal. The ability of Strychnos potatoram seed emulsion to both clarify source waters was investigated as coagulation pretreatment for solar disinfection. This coagulant reduced the turbidity by more than two-thirds and achieved up to 1-log10 bacterial removal (90%). The combined Strychnos potatoram coagulation -solar disinfection treatment sequence was tested in highly turbid natural source water and was found to reduce the sunlight exposure time required by up to 2 hours. However, despite being an effective clarification and turbidity removal process, the pretreatment may not shorten the overall treatment time because of its own labor and time requirements, potentially decreasing the treatment compliance rates. In addition, while total coli form regrowth was observed during overnight storage of the treated water, no Escherichia coli regrowth was found to occur. 1. INTRODUCTION At least one third of the population in developing countries has no access to safe and reliable drinking water supplies. The lack of adequate water supply and sanitation facilities seriously exposes this unserved population to numerous water related diseases. Lack of public water supply implies that a large part of the rural population is still forced to use contaminated surface water. Unreliable public water supply due to frequent interruptions or breakdowns drives people back to polluted water sources. Public water supply which distributes water unsafe for consumption exposes the supplied population to a considerable health risk. As a consequence, substantial investments will have to be made in order to achieve full coverage in the near future. Choice of inappropriate technologies, missing operation and maintenance work, difficulties in the procurement of fuel and spare part, and weak management structures often account for the poor performance of many existing public water supplies in developing countries. [4-7] Self help individual water supply systems operating at household level is certainly one approach that will fulfill these criteria. Boiling of water, disinfection with chlorine and filtration through ceramic filters are treatment methods often propagated at household level. Boiling of water requires energy which in rural areas is usually supplied in form of firewood. This type of water treatment is no longer a good practice. Disinfection by chlorine compounds is often rejected by the consumers due to the undesirable taste and odor acquired by the water. Filtration through ceramic filters is often an unaffordable treatment method. However, apart from being expensive, ceramic filter candles are subjected to frequent clogging and often leak through fine cracks caused by careless handling. [8-10] The state problem call for the development of alternative treatment techniques that is effective, practical and simple enough to be applied by individuals or households. Solar water disinfection is considered to be such an alternative. The treatment process is simple technology using solar radiation to inactivate and destroy pathogenic bacteria present in water. [11-14] However, solar water disinfection has its limits too. Solar radiation in dependent on the geographic location and climatic conditions, and undergoes diurnal and annual variations. The application of solar water purification is simple. However, exposing a small quantity of contaminated water to solar radiation is a complex interaction of physical, chemical and biological processes which are not yet clearly understood. [15- 17] Solar radiation is an ancient disinfection practice used without profound understanding of the process. However, different research groups have recently started to study the process of solar water disinfection. Under extreme poverty in rural and peri urban communities low cost house hold water treatment solutions are vital for general health and well being of a community. One of these household treatments is solar water disinfection [15], whereby