Zero excess sludge wastewater treatment with value-added substances recovery using photosynthetic bacteria

Conventional wastewater treatment processes produce large amounts of excess sludge that demand expensive treatment and disposal. This study proposes a new strategy of zero excess sludge wastewater treatment using photosynthetic bacteria with value-added substances generation and recovery. The strategy used photosynthetic bacteria to effectively purify wastewater and synthesized cells; then five value-added substances, coenzyme Q(10), carotenoids and bacteriochlorophyll, 5-Aminolevulinic acid, and protein, were successively extracted from photosynthetic bacteria cells with >75% efficiency compared to the separated extraction of each substance, leaving the residual bacterial biomass to be used as fertilizer. Thus, zero excess sludge is achieved by wastewater treatment with nutrients recovery. Also, for the first time, all five value-added substances in photosynthetic bacteria cells were successfully recovered, which helps the economic balance sheet. This method presents a promising alternative for traditional wastewater treatment and shows a new approach of "zero excess sludge" in wastewater treatment, which is in line with the requirements of sustainable development and promotes the development of cleaner production. (c) 2019 Elsevier Ltd. All rights reserved.