Performance evaluation of the combined process of ozonation, biological activated carbon reinforced by bacterial consortium, and ultrafiltration in greywater treatment

Because of the growing population and increasing freshwater consumption, treatment and reuse of greywater have been widely considered. The application of a new and environmentally friendly treatment method for synthetic and real greywater (RGW) is of utmost importance. This study aimed to evaluate the efficiency of the combination of ozonation, biological activated carbon, and ultrafiltration (O3/BAC/UF) in the removal of chemical oxygen demand (COD), turbidity, five-day biochemical oxygen demand (BOD5), and linear alkylbenzene sulfonates (LAS) from synthetic greywater and RGW.

Bacillus Subtilis, Acinetobacter radioresistens, Pseudomonas aeruginosa, and Ochrobactrum oryzae were selected from nine pure bacterial species and transferred to granular activated carbon (GAC), then, mineral culture medium was added to the reactor for the growth and establishment of bacterial consortium. The SEM method was employed to ensure the formation of a microbial layer on GAC. Then, the continuous flow of synthetic greywater (for six months) at a low: 6.1, medium: 12.2, and high: 18.3 gCOD/L.d organic loading rates as well as RGW (for two weeks) entered the treatment system.

The percentages of COD removal in low, medium, and high organic loads of synthetic greywater and RGW were 85.12%, 79.05%, 85.3%, and 98.65%, respectively. Moreover, the percentages of BOD5 removal were 87%, 82%, 51%, and 92%, respectively. Furthermore, the percentages of turbidity removal were 93.5%, 97%, 96.69%, 73.33%, and the percentages of LAS removal were 91.4%, 88.1%, 84.8%, and 93.7%, respectively.

The treatment system has a remarkable ability to remove pollutants from greywater and can be used as a new method of greywater treatment in Iran.