Economically Viable Nature-based Sewage Treatment Method by Using Life Cycles of Mosquitoes and Non-biting Midges

Abstract

The presence of sewage in the surroundings is loathed by humans and animals as it emits an unbearable foul smell. However, many aquatic insects flourish, with their life cycles occurring in polluted water, such as sewage. This is a conceptual paper proposing the use of aquatic life cycles of mosquitoes and non-biting midges in sewage treatment. Sewage is nothing but water contaminated by human faeces and urine, which is mainly organic matter. Theoretical research is conducted to conceptualise a method for producing valuable insect biomass from the organic matter in sewage, so that such a sewage treatment method can earn a reasonable profit on the incurred capital investment after deducting the operating and maintenance costs. The data needed for this conceptual paper are compiled or extracted from the relevant research base/literature available online. The study presented in this paper has found that the proposed sewage treatment process mimics a natural biological process occurring in polluted water. Currently, sewage is considered a waste product that must be treated at a cost before being discharged safely into natural water bodies. It transforms wastewater into a productive resource by deriving value addition in an environmentally friendly and harmless manner. Unlike existing wastewater treatment systems, the proposed process is profitable by selling insect nutrient-rich biomass as an ingredient in fish/poultry feed. It is a bio-energy with carbon capture and storage process if the generated carbon-neutral or bio-carbon dioxide gas is captured and sequestered in a downstream process. The proposed process is part of the circular economy as waste is converted to wealth in an environmentally friendly way without causing air pollution. Each acre of land used, without any water footprint, for the proposed sewage treatment system is productively equivalent to 700 acres of irrigated agricultural land. The proposed sewage treatment plants can also be used to rear large numbers of Wolbachia and sterile male mosquitoes to prevent mosquitoes from acting as disease vectors. The study also finds that further lab-scale research is needed to select suitable species of mosquitoes and non-biting midges, to determine optimal indoor air quality, and to determine the optimal dissolved oxygen in the sewage that can enhance the yield of insect biomass. There is a lack of scientific literature on non-biting midges. India has an ultimate annual potential of 77 million tonnes of aquatic insect biomass from the available carbon-neutral sewage.