An integrated approach for selection of sanitation options for Nakuru, Kenya with focus on Ecosan

Nakuru is the fourth largest town in Kenya. Its population has been growing rapidly and hasexerted strain on existing water and wastewater management facilities. Due to high costs of aconventional sewerage system, the municipality has not been able to expand the network tomatch the rate of growth of population. It is also not able to meet its daily water demand andthe sewer network serves only 40% of the population. The alternative methods used in theunsewered areas lead to environmental and sanitary problems. Hence there is a need to look foralternative sustainable sanitation solutions.Ecosan (ecological sanitation) may offer a sustainable alternative sanitation solution. Ecosan isa concept that treats human waste as a resource and tends to minimize water use. But itsapplication has not been widely tested in Kenya to date. Limited awareness and socio-culturalbarriers on handling of human waste have been constraints in adoption of this concept. Thisstudy therefore seeks to use an integrated approach for selection of sanitation options withfocus on ecosan while recognizing that socio-cultural factors play a key role in the success ofsuch innovative projects.To achieve the objective set out, a household survey was carried out in three representativeresidential areas in Nakuru namely kwa Rhonda, Lakeview and Millimani. They all have noconventional sewerage network and experience regular water supply shortages. kwa Rhonda ischaracterised as a low-income high-density area, Lakeview is low to medium income, highdensity; and Millimani is characterised as high income, low density. A total of 239 randomlyselected households were interviewed. Additionally, interviews were held with otherstakeholders such as the municipal council and toilet contractors. A desktop study was alsocarried out to collect additional secondary data needed for the selection process.The climatic and geological conditions of Nakuru were found to be suitable for on-site ecosansystems. The results of this study showed that although there is a low awareness of re-useoptions for human waste within the study areas, a strong willingness to use ecosan-supportingtechnologies such as urine diversion (UD) toilets exists. However high installation costs,hygiene issues, lack of knowledge on use and maintenance were seen as the biggest challengesto use of UD toilets in ecosan systems. The choice of selected ecosan-compatible toilets wasstrongly influenced by the type of toilet currently in use and the characteristics (socioeconomic)of each area. Agricultural practices within residential areas are currently limited forthe areas with lower property sizes and household incomes (kwa Rhonda and Lakeview).Innovative farming practices, such as vertical horticulture, for these areas are necessary in orderto close the nutrient loop on-site. This study also revealed that water costs account for asignificant portion of a household's income (18-56% depending on household socio-economicstatus), and technology options that are based on the ecosan concept may help to conservewater and save costs.The outcome of the survey was considered together with a variety of sanitation technologiesfound from review to be suitable for the Nakuru situation. Three area-specific options for eacharea were short-listed for comparison. In the selection process, kwa Rhonda and Lakeview wereconsidered together because of similarities in existing sanitary conditions. Based on publishedsustainable planning criteria (and own weightings of the criteria), final options for each areawere selected as follows:For Millimani - Low flush no-separation toilet connected to a septic tank was selected. Inthis option, urine and grey water are reused on-site whilst the septic tank sludge is subjectto secondary treatment off-site. Other options were the low flush UD toilet with biogasand low flush UD toilet with on-site composting. For kwa Rhonda and Lakeview- Dry UD toilet with solar drying was the most suitable. Inthis option, sludge is treated off-site while urine and grey water are treated on site forreuse. Excess greywater is discharged off-site. Other options were dry UD toilet with drybiogas production and the pour flush toilet with solar drying.The UD toilets were found not to be the suitable for Millimani. The factors related to sociocultural,technical and institutional issues outweighed reuse and water conservation thatcharacterizes UD technologies. The selection process demonstrated that choices could be madefrom a variety of options relevant to the area-specific requirements unlike in the case ofcentralized conventional sewerage systems.The ecosan technologies selected did not close the nutrient and water loops on-site thusrequiring off-site secondary treatment and re-use. A centralized system for secondarycomposting was viewed as a possible solution to help close the loop off-site. This is achievablethrough a partnership between the municipality and private sector in transport, treatment andsale of both raw and finished products. However development of an institutional frameworkand stakeholder linkages are necessary for this to be achieved.Biogas generation and use was seen to be a strong potential demand driver that can be linked tosustainable ecosan sanitation options. It is of immediate value to the user's day-to-day energyneeds. Its use should therefore be encouraged as part of a strategy to encourage the ecosanapproach in reuse of waste streams (even though, for various reasons, it was not selected as theoptimum choice for the areas under consideration in Nakuru)