From waste to wow – Low cost green technology for domestic wastewater treatment for reuse and beneficiation

Abstract

Phycoremediation makes use of macroalgae or microalgae and can be used to treat wastewater. This technique has the potential to be used as an alternative biomass source for bio-energy production. The current study utilizes a specific consortium of algal species (isolated and cultured in the laboratory) to reduce nutrients and create conditions suitable for effective reduction of pathogens in WWTW as well as reclamation of water in water scarce countries. The aim was firstly to implement a self-sustaining system that is independent of electricity or expensive chemicals and that can be effectively operated within the current financial and capacity constraints of developing countries using existing infrastructure i.e. waste stabilisation pond systems. Secondly, it was to establish the feasibility of algae biomass generated from maturation ponds as bio-energy. This low cost green technology has already been rolled out with great success at two waste water treatment works in South Africa. To date, total phosphate removal efficiencies of 87.1% and nitrogen levels of 56.3% was achieved in final effluent. E.coli numbers were reduced to below Department of water and sanitation guideline levels. Under auspices of the African Development Bank's Africa Climate Technology Centre, the research team recently started a small scale pilot plant for the drying of algae biomass under natural climate conditions at the rural Brandwacht domestic waste water treatment plant. The next step will be to determine the algal biomass that can be generated for bio-energy using a specific consortium of algae under natural drying conditions. If enough algae biomass is generated, the team will explore the possibility of using this algae biomass to generate bio-energy for the small rural town of Brandwacht. Pending a health risk assessment, bio-fertiliser production or pelleting the biomass for animal feed are other products under investigation.