Investigation of the effectiveness of rice straw nanobiochar treated with Bacillus subtilis bacteria in reducing the concentration of surfactants

Urbanized areas are characterized by high traffic of motor vehicles, which in turn requires regular maintenance, including washing. Car wash enterprises operate in various modes - manual, automatic, semi-automatic, but in any case, significant volumes of water are required. Wastewater is characterized by high concentrations of various pollutants, including surfactants. In the case of discharge of untreated wastewater into a body of water, surfactants can initiate the process of eutrophication in it, thereby disrupting the existing ecosystem. In this regard, the aim of the research presented in the article is to reduce the concentration of surfactants by the method of sorption treatment using rice straw nanobiochar processed by Bacillus subtilis bacteria. According to the literature review, previously published works have established the high efficiency of rice straw biochar in reducing the concentration of surfactants. However, the presence of heavy metals in wastewater reduces the adsorption efficiency of surfactants. It is known that Bacillus subtilis bacteria are capable of bioaccumulating heavy metals and also directly cause degradation of Bacillus subtilis. In addition, literature sources provide information on the possibility of using nanobiochar as a carrier of Bacillus subtilis bacteria. Based on the above, studies were conducted to reduce the concentration of surfactants in model waters with an initial value of 9.5 mg/l at a sorbent dose of 2.0 mg/l. In addition, the physicochemical and sorption properties of processed nanobiochar were studied, electron microscopy photographs were obtained, thermogravimetric analysis was carried out, and its diffractogram was made. The sorption process itself was carried out in a static mode with a contact time of 10, 20, 30, 40, 50 minutes. According to the experimental data, the optimal result was obtained with a contact time of 10 minutes.