f) Filtering Unit The treated effluent separated in the upstream settling tank contains suspended solids which in turn include phosphorus and nitrogen. In order to achieve the required guidelines for T-N and T-N it is required to use filtration to remove the suspended solids from the effluent. For this purpose a self-cleaning sand filtration unit is used. g) Chlorination Unit The filtered effluent is then treated by chlorination in order to remove pathogens. The system uses for disinfection a solution of NaOCl, which is effective and economical. The treated effluent is then discharger to the nearest receptor either by gravity or by the use of pumps (if required). h) Sludge Treatment The excess sludge is pumped from the settling tanks for thickening and dewatering. Thickening is performed by the use of mechanical means (e.g. gravity-belt thickener, rotary drum etc.) and is aided by the use of polyelectrolyte. Dewatering is also performed by the use of mechanical means 35
(e.g. belt-press, centrifuge etc.) and polyelectrolyte. Leachate from the sludge thickening and dewatering is recirculated back to the biological treatment. 5.6 Green Building Alternative 5.6.1 Introduction Green building in Kenya or green construction is beginning to take course, albeit slowly in Kenya’s construction scene. Developers are placing an emphasis on producing houses that are environmentally and resource friendly. It is a rather misunderstood term, with some painting their houses green to keep in sync. Green building entails constructing and managing buildings economically, with an emphasis on reducing environmental burdens and conserving resources. It involves the choice of materials and products used to achieve the best performance at building level. For it to be effective, it should encompass the whole building cycle, from design, construction, operation, maintenance and daily running of the building. Several assessments in relation to green building in Kenya have identified that substantial savings in cost, embodied Carbon, electricity and water consumption are possible in housing structures currently being built in Kenya making it more green and affordable. The current Muranga County climate is ideal for the design of energy efficient housing. A well-designed building i.e. orientation and careful position of openings and selecting building materials will minimize the requirement of lighting and heating in the structures saving electricity or other fuels. Even though there is no need for any air-conditioning in Muranga County housing structures it shouldn’t be forgotten that unchecked construction and poor structural designs can often result in higher than normal temperatures so people resort to energy consuming air-conditioning. It will be important for proper ventilation and air conditioning to be done in the proposed project owing to the nature of the work to be carried out in the factory because machines are expected to generate heat and fresh and cool air will be required. The construction technology most prevalent in places with similar environmental
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- Winter '19
- Sewage treatment, Environmental impact assessment, Proposed Project, Food processing