Out of some 175 urban centres in the country, only 47 operate conventional sewerage systems and treatment plants
There has been brisk urbanisation in Kenya in recent years, bringing into sharp focus water resource availability and the other side of the equation — waste recycling and treatment, or sanitation. Only 58 percent of the population is currently estimated to have access to clean water, while a mere 30 percent has basic sanitation facilities.
Urbanisation has brought with it pollution of water resources, besides unmet demand for clean water. Given these circumstances, developers of houses, besides local authorities, have become crucial in water saving and waste treatment, specifically given the low formal coverage by service providers in the sprawling urban areas. Out of some 175 urban centres in the country, only 47 operate conventional sewerage systems and treatment plants, according to Government records.
The State Department of Housing and Urban Department and the Ministry of Transport, Infrastructure, Housing and Urban Development, are at the vanguard of development of green buildings, with a major focus on water savings and energy efficiency. Complementary efforts have been pushed through USAid and the State. The Government is seeking to support the private sector through research and incentives to achieve this goal, with the objective widely shared by the private sector and non-governmental organisations.
The Kenya Building Research Centre (KBRC), founded in 1957, is at the heart of the bid to develop sustainable or green buildings through provision of pertinent information to leverage the built-environment.
Besides the utility providers, research points to various ways that water conservation and efficiency can be achieved, particularly through the development processes. A key one here is the design of water harvesting systems, a function already being addressed, inter-alia, by the National Water Harvesting and Storage Authority.
A lot has as well been achieved through private efforts by developers and homeowners to tap rain water for both drinking and sanitation, a situation that has resulted in massive investment in the private moldings industry to supply gutters, water and sanitation tanks. Water-efficient appliances have become common, as well as correct disposal of waste water for, among other purposes, landscaping and kitchen gardening. The KBRC is at the centre of research to make the generated information available to contractors and homeowners.
Urbanisation has brought with it pollution of water resources, besides unmet demand for clean water. Given these circumstances, developers of houses have become crucial in water saving and waste treatment
A big goal of the water efficiency research is the employment of appropriate drainage systems in built-environments to sustain the water system. Here, the runoff rainwater is facilitated to infiltrate the water table that has come under great pressure owing to lack of formal water supply in the majority of municipalities — many of which have come up in less than two decades. As already noted, attenuated municipal coverage has helped turn the attention to waste systems.
Apart from sanitation, research has focused on processing bilge water into a useful resource. The bio-digester system that separates waste from water through filtration is emerging as a favourite, particularly when space is utilised professionally. The system filters waste water for use in cleaning and landscaping, among other chores.
Further complementally cleanup of the environment can be achieved by sorting garbage into bio-digestible and solid waste, which can reduce the disposal volumes by leaving usable waste for gardening and the rest for recycling. The KBRC has been selling this concept under the three Rs campaign — Reduce, Recycle, Reuse.
Landscaping in the emerging urban environments is seen as fundamental in the water management cycle. Reuse material and rainwater are exploited through appropriate designs of the built-environments. Notably, water harvesting to ease the burden on municipalities is being emphasised by the Water Harvesting Authority, with counties like Kajiado enforcing this through bylaws. In the water efficiency building plan, the non-paved areas are designed to absorb rainwater through planting of hardy indigenous trees that require limited water supply. Hard landscaping here is recommended with materials that allow water to permeate through.
Also, paving has to be limited around buildings to avoid the “heat island effect”.
The systems have become popular in Kenya owing to low utility coverage, with multiple suppliers emerging and research recommending their use. The cost depends on the size of the bio-digester tank and the use it is employed for. The users may be 1-30 people for small bio-digesters, to those that are continuously used by 120 people in large establishments.
According to some estimates, for a simple residential house, the cost can start from KSh70,000. But for a multiple dwellings apartment, it can go up to KSh300,000. At the end of the day, it all depends on the contractor and their use of the technology and materials. The facility has an inlet for waste water and toilet waste into a septic tank that releases water into a soak pit.
They are designed to host bacteria from human and other biodegradable wastes to facilitate aerobic and anaerobic decomposition. Enzymes are put in the semi-solid tank as catalysts for eating up the waste. However, good designs ultimately direct water to the soak pit where it is recycled — after removing oils and soap residuals — for landscaping, toilet reuse and other utilisation.
Bio digesters have become popular in Kenya owing to low utility coverage, with multiple suppliers emerging and research recommending their use. The cost depends on the size of the bio-digester tank and it’s use
The process saves on sewage exhaustion costs of between KSh6,000 to KSh15,000 a tank in peri-urban areas of Nairobi. Caution nevertheless
is urged where the recycled water cannot be properly disposed or utilised as this can cause entirely new problems of pollution and contravention of municipal by-laws.
There are a number of benefits that are drawing users to biodigesters. The most obvious is that they require little maintenance, with the exhausting function eliminated. The initial cost of excavating a conventional septic tank is normally daunting in areas with hard rocks — a lot of times requiring machinery to drill. It also requires heavy concrete and wire mesh or steel reinforcement to avoid leakage in both rocky grounds and loose soils. More often than not, conventional septic pits will end up letting in liquids from other sources, making exhaustion both expensive and thankless.
The septic tank has a foul smell that can backflow to the housing units as it fills up. But the D-day, of course, is the time the exhauster comes to empty the tank, making the area almost uninhabitable.
With a cylindrical shape, it is better able to withstand pressure and normally comes with a warranty. A single unit, as approved by the National Environmental Authority (Nema), can have a lifespan of at least 30 years. Generally, the Government is encouraging contractors to adopt the World Bank’s International Finance Corporation (IFC) Excellence in Design for Greater Efficiencies (EDGE) tool. Here, buildings have to exhibit 20 percent rate in energy and water consumption for EDGE certification.
This will, additionally, help secure bank funding that has already started flowing into green buildings, including the Arcon Hostels projects that cater for students.