Determination of kinetic constants and coefficients of biological processes of wastewater treatment of egg advanced processing enterprises

Summary

The results of studies carried out in contact conditions with active sludge of a laboratory batch reactor with wastewater from an enterprise for advanced processing of chicken eggs are presented. In the course of kinetic experiments based on measuring the rate of dissolved oxygen consumption the following averaged values of the kinetic constants of the biological treatment processes were established for wastewater after preliminary coagulation: the maximum rate of oxygen consumption at a sludge concentration a_i → 0 ρ`_max = 44.8 mg/(g·h) in terms of a temperature of 20°С; Michaelis constant K_m = 77.5 mg/l; coefficient of inhibition by metabolic products φ=0.265; temperature constant χ = 0.08°С^–1; optimal pH value 7.8 and pH constant 80. During the experiments with raw wastewater, the following average values of the constants were determined: the maximum rate of oxygen consumption at 20°С and a_i → 0 ρ`_max = 26.5 mg/(g·h); Michaelis constant Km = 50.6 mg/l; coefficient of inhibition by metabolic products φ=0.065; temperature constant χ = 0.1°С^–1; pH_opt 7.8 and Kр_Н = 170. The obtained values of kinetic constants and coefficients can be used in the calculation of biological wastewater treatment facilities of an egg processing enterprise.

Key words

wastewater , biological treatment , kinetic constants , food industry , egg processing enterprise , batch reactor

Results of studies of biological wastewater treatment of an egg processing enterprise

Summary

Biological treatment of wastewater of an enterprise for enhanced processing of chicken eggs in a batch reactor (SBR) has been studied. The treatment of both raw and pre-coagulated wastewater under aerobic and anoxic-aerobic conditions was studied in a 5-liter experimental unit for four months. In the course of the experiment in the treatment of raw wastewater with an average COD sludge load of 0.18 g/(g·day), average concentrations of pollution in the effluent were obtained, mg/l: COD – 253, BOD_total – 58.4, suspended solids – 11, ammonia nitrogen – 2.1, nitrite nitrogen – 0.06. The average values of the specific rate of oxidation of organic substances as COD, normalized to 20°С, amounted to 9.8 mg/(g·h); as BOD_total 7.2 mg/(g·h). While operating SBR with wastewater after physical and chemical treatment, with an average COD load of sludge of 0.15 g/(g·day), the effluent was characterized by the following average values, mg/l: COD – 99; BOD_total – 15.4; suspended solids – 10; N–NH₄ – 1; N–NO₂ – 0.04. The average values of the specific rate of oxidation of organic substances as COD at 20°С turned out to be 8.3 mg/(g·h) and as BOD_total – 5.7 mg/(g·h). The concentrations of nitrogen nitrates in the effluent in two anoxic phases in the SBR cycle averaged as follows: during raw wastewater treatment – 21.7 mg/l, and during pre-coagulated wastewater treatment – 15 mg/l.

Key words

wastewater , biological treatment , food industry , egg processing enterprise , batch reactor