Combined treatment of meat processing plant wastewater

Wastewater from slaughterhouses at meat processing plants is characterized by relatively high levels of organic compounds, which pose a significant environmental problem. The chemical oxygen demand (COD) value of such wastewater, often exceeding 17,000 mgO2/L, indicates a real challenge in its treatment.

We previously demonstrated that treating five-fold diluted slaughterhouse wastewater with bacteria of the genera Bacillus, Polymyxa, and Nocardia results in a reduction in organic matter content, resulting in a decrease in COD by approximately a quarter. However, this reduction still does not allow for discharge into the environment.

The aim of this study is to evaluate the effectiveness of a combination of physicochemical and biological methods for treating the aforementioned wastewater.

In the first stage of disinfection, the five-fold diluted wastewater was treated with a polyaluminum oxychloride-based coagulant. An aqueous coagulant solution with a mass fraction of Al2O3 = 1% was added to the wastewater. The optimal coagulant dose was a wastewater:1% coagulant solution ratio of 25:1-25:0.8. As a result of treatment, the wastewater became clear and lost more than 1.5% (by wet weight) of impurities in the form of coagulated sediment.

In the second stage, water clarified by coagulation was treated with bacteria of the genera Bacillus, Polymyxa, Nocardia, and Streptomyces. The results of a series of experiments showed that the properties of the water clarified after bacterial treatment allow its discharge into the environment.

The results of this study are intended to be used as part of the initial data for the design of a wastewater treatment technology for meat processing plants.