Development of Biological Livestock Wastewater Treatment System Combined with Physical Pretreatment and Chemical Posttreatment

Abstract

Lab-scale livestock wastewater treatment process was operated. Treatment process was composed of anaerobic reactor, aerobic reactor, anoxic reactor, settler, and microorganisms activation reactor. We divided this system into Systems 1–5 according to various conditions. In Systems 4 and 5, ammonia stripping was performed as pretreatment. And flocculation was performed as posttreatment. Average influent concentrations of COD, BOD, TKN, and TP were 21,894, 11,533, 2255, and 415 mg/L, respectively, and COD/N and BOD/N ratios in influent were 9.9 and 5.3, respectively. When ammonia stripping was performed as pretreatment, effluent BOD concentration was 44.4 mg/L and removal efficiency was 99.62%. TN removal efficiencies in Systems 4 and 5 were 84.1 and 95.2%, respectively, and effluent TN concentrations were 305.9 and 78.4 mg/L, respectively, which was because of with/without pH control. In operation period of Systems 4 and 5, average SNR and SDNR were 18.6 and 17.4 g N/kg MLSS/d, respectively, which was rate as much as endogenous denitrification rate because of long SRT due to low F/M ratio. In Systems 3, 4, and 5, optimal doses of flocculation agent were 350, 100, and 100 mgFe/L. This difference was caused by alkalinities of Systems 3, 4, and 5, which were 750, 284, and 162 mg/L as CaCO₃.

Keywords:

• Ammonia stripping
• Denitrification
• Flocculation
• Livestock wastewater
• Nitrification