Household discharge of chemical products and its classification based on anaerobic biodegradability.

Synthetic household chemical products (HCP) are used in various household activities. An average urban household was estimated to consume ~ 3 kg HCP per month while discarding 212-387 mg/L HCP in sewage comprising > 265 different chemical compounds. The high sorption properties of HCP and their antimicrobial resistance lead to their long-term persistence in the environment. The intrusion of HCPs and their breakdown products into food chain causes detrimental effects on health and ecology. HCPs comprise mostly of a mixture of xenobiotics, organic and inorganic compounds resulting in an impaired biodegradation. Yet, the biodegradability of HCPs is seldom assessed. Therefore, this research proposes a modified Gompertz model approach to analyze BMP data in order to classify commercially available HCPs into seven groups based on the observed levels of recalcitrance and is in turn coined "Anaerobic Biodegradability Index" (ABI, beginning from ABI-VI to ABI-0 wherein ABI-VI represents the highest degradability and ABI-0 the least). This approach emulates "Energy-Star" ratings of electrical appliances classified based on electrical efficiency. Results of such a classification indicated that HCPs containing ≥ 10% anionic surfactants such as laundry detergents, handwash gel, dishwasher chemicals, and creosote surface cleaner, exhibit lowered anaerobic degradability and were therefore categorized between ABI-0 and ABI-II. Whereas the highly degradable HCP such as toothpaste, shower gel, and hair shampoo were categorized in ABI-V and ABI-VI categories. We perceive that the weightages and concentrations can be used in the future to define the capability of various wastewater treatment systems and their tolerance to various ABI classes.