Wastewater Treatment using BSF larvae: Influence of larvae density and solid support.

Recently the biological treatment of wastewater with the use of Black Soldier Fly (BSF) larvae has been studied with promising results, particularly in the case of high organic content (HOC) wastewater, such as sewage from food industries, leachate from municipal solid waste (MSW) landfill, etc. The use of a physical support for the larvae mobility has been suggested and patented to overcome the issue of high larvae mortality under pure liquid conditions. Moreover, the process influencing variables and removal kinetics have been studied under different HOC wastewater, providing design parameters for real scale treatment plants. For the scaling up of the process, the definition of type of physical support and larvae density are still to be investigated. The aim of this study was to achieve a better knowledge of the optimal operational conditions in terms of supporting material and larvae density, to maximise the liquid volume per unit of reactor volume and the organics removal per unit of reactor surface without compromising survival rate of larvae and maximising the treatment performance. Three distinct supporting materials (Valox® plastic granules, Kaldnes® and geomat) were tested at four different larvae densities (4, 8, 16 and 32 larvae/cm2). The larvae were fed with the same artificial wastewater (low-fat milk diluted with water, 1:10) under same organic load. The biological treatment performance was assessed by monitoring both the larvae growth (in terms of weight variation and prepupation) and Organic Carbon removal performance.