Characteristics and functionality of high efficiency composite microbial flocculant (EPC-7) for the treatment of black smelly river wastewater

The utilization of bioremediation technology for treating black, odorous river wastewater has the potential to significantly increase treatment efficacy and safeguard the environment. This study delves into the preparation of composite microbial flocculants and their effectiveness in treating black, odorous water bodies, as well as their associated mechanisms. Three microbial flocculant-producing bacteria were cultivated and screened from activated sludge, which were then compounded to form a composite microbial flocculant. The flocculation efficiency was evaluated in a black odor water system with the zeta potential and UV value of the flocculation system analyzed to identify factors that affect effectiveness. The results indicate that combining microbial flocculant with CaCl2 significantly boosted flocculation efficiency. Optimal conditions include a neutral pH (pH = 7), 2 mL/L of 1 % (w/v) CaCl2 addition, and 3 g/L of microbial flocculant dosage. Under these optimal conditions, COD, TN, NH3, and Mn (PO4)3 removal rates exceeded 90 %. Composition analysis revealed the protein content of the flocculant accounted for 49 %, followed by polysaccharides at 23 %. Through Fourier Infrared Spectroscopy (FT-IR), Nuclear Magnetic Resonance (1H NMR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM), it was confirmed that the flocculant contained carboxyl, hydroxyl, and amino groups which promoted the adsorption bridging effect. The primary mechanism involved in the flocculation process being adsorption bridging followed by charge neutralization. The protein-based flocculant displays significant potential in addressing black smelly river water pollution due to its low cost, low dosage, eco-friendly nature, and efficacy.