Use of vegetative wastewater treatment systems for counties’ effluent management in Kenya

Abstract

In Kenya, the devolved system of governance to counties is currently facing many challenges in the provision of basic services including wastewater management. Thus there is an attempt to explore the feasibility of using vegetative wastewater treatment systems that are economically viable and environmentally sustainable. The viable options available include: Constructed wetlands; use of micro-algae and the use of Moringa Oleifera, as an herbal coagulant.

Constructed wetlands treatment systems are engineered systems that consist of two general categories namely: subsurface flow systems and free water surface systems. The subsurface flow systems have also been referred to as root zone systems; rock reed filters and vegetated submerged bed systems. Free water surface systems are frequently designed to maximize wetlands habitat values and reuse opportunities, while providing effective water quality improvement.

Microalgae culture offers an interesting step for wastewater treatments, because they provide a tertiary biotreatment coupled with the production of potentially valuable biomass, which can be used for several purposes. Microalgae cultures offer an elegant solution to tertiary and quandary treatments due to the ability of microalgae to use inorganic nitrogen and phosphorus for their growth. And also, for their capacity to remove heavy metals, as well as some toxic organic compounds, therefore, it does not lead to secondary pollution.

The use of Moringa Oleifera, an herbal coagulant, which is free of constraints viz. pH and alkalinity, has been used to reduce wastewater pollution significantly in some studies. The results of the studies showed that an optimum dose of Moringa Oleifera (60 mg/L) was observed to reduce pollution parameters - initial BOD5 and COD of dairy wastewater to the tune of 55% and 60% respectively. This review highlights on the use of vegetative wastewater treatment systems like constructed wetlands, micro-algae and Moringa Oleifera in effluent management in counties of Kenya.

Keywords: constructed wetlands, micro-algae, Moringa Oleifera, wastewater, faecal coliforms, coagulation