Moringa oleifera is an important multipurpose tree introduced to Africa from India at the turn of this century. Despite limited knowledge of the levels of genetic diversity and relatedness of introduced populations, their utilization as a source of seed for planting is widespread. In order to facilitate reasoned scientific decisions on its management and conservation and prepare for a selective breeding programme, genetic analysis of seven populations was performed using amplified fragment length polymorphism (AFLP) markers. The four pairs of AFLP primers (PstI/MseI) generated a total of 236 amplification products of which 157 (66.5%) were polymorphic between or within populations. Analysis of molecular variance (AMOVA) revealed significant differences between regions and populations, even though outcrossing perennial plants are expected to maintain most variation within populations. A phenetic tree illustrating relationships between populations suggested at least two sources of germplasm introductions of Kenya. The high levels of population differentiation detected suggest that provenance source is an important factor in the conservation and exploitation of M. oleifera genetic resources.

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Seeds of the pan tropical tree, Moringa oleifera Lam. (M. oleifera) contain water soluble, positively charged proteins that act as an effective coagulant (molecular weight 13 kDa and isoelectric pH 10-11). Treatment studies are reviewed using the extracts of the crushed seed kernel and of the presscake (solids residue remaining after oil extraction). M. oleifera seed was incorporated into a pilot scale treatment system as a primary coagulant to clarify river water of 400 NTU in the wet season. Over 90% turbidity removal was achieved in the sedimentation stage at a dosage of 100 mgL-1. The filtrate turbidity was maintained well below 5 NTU. Subsequent trials were conducted in an adjacent works operating at 60 m3h-1. Treatment performance was comparable to that of using aluminium sulphate. Inlet turbidities of 270-380 NTU were consistently reduced to below 4 NTU. A comprehensive study was undertaken to evaluate the potential of using M. oleifera coagulant within a contact flocculation filtration (CFF) pilot rig. A wide range of operating conditions was evaluated in order to establish the useful “working envelope” for this process combination (filtration rates 5-20 mh-1, initial turbidities 20-50 NTU). Principal results are presented. As a coagulant within chemically enhanced primary sedimentation (CEPS) of a mixed wastewater, M. oleifera dosed at 150 mgL-1 gave additional removals (compared to a plain sedimentation control) of 40% biochemical oxygen demand (BOD) and chemical oxygen demand (COD) and in excess of 80% for suspended solids (SS). Subsequent laboratory work coupled an upflow anaerobic sludge blanket reactor (UASB) to CEPS. M. oleifera coagulant in the CEPS pre-treatment unit beneficially increased the ratio of soluble COD to volatile SS by a factor of ten compared to plain sedimentation and by a factor of three when dosing ferric chloride. The UASB yielded more biogas and gave enhanced COD removal. Recent work on the extraction and purification of the active coagulant components is reviewed and the prospects for commercialisation are considered.

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