Effects of Powdered Kenaf Supplementation on the Performance of Lab-Scale Activated Sludge Reactors

A porous powder of dried kenaf (plant), when added to mixed liquor (ML), might provide submerged surface area for biofilm development within suspended growth WWTPs, which could improve plant performance without costly modifications. The performance of bench-top sequencing batch reactors, fed municipal wastewater and carrying out enhanced biological nutrient removal was compared. Kenaf powder was not found to have a significant effect on carbon, phosphorus or suspended solids removal. At optimal aeration intensity, kenaf did not affect nitrogen removal. However, when aeration intensity was below ideal, nitrogen removal was less adversely affected in the kenaf reactor than in the control. A lower sludge volume index with kenaf treatment provided evidence of improved sludge settling. Arsenic, copper, lead and zinc accumulated more in the kenaf treated ML solids, while cadmium, chromium and nickel did not. Batch testing suggested that kenaf enhanced nitrite oxidizing bacteria activity, possibly leading to improved nitrification.