Abstract:Flocculation is an efficient and cost-effective technology for treating pig farm biogas slurry, with its effectiveness being significantly influenced by environmental temperature. In order to study the influence of ambient temperature on flocculation efficacy and processing parameters of biogas slurry in a pig farm, this study optimized the flocculation process parameters under three distinct temperature conditions (low: 2~9 ℃, medium: 11~17 ℃, and high: 29~36 ℃) through indoor simulation tests, aiming to explore the best flocculation effect and optimal process parameter values. The results showed that with the increase in ambient temperature, the smaller the optimal value of flocculant dosage and stirring speed, as well as the larger the optimal value of pH; furthermore, the best flocculation effect was achieved under medium temperature conditions, surpassing those at low and high temperatures. The optimal values of the dosage of polyaluminum chloride (PAC), the dosage of polyacrylamide (PAM), the pH value, and the stirring speed under three ambient temperature conditions are as follows: low temperature (7.24 g/L, 96.91 mg/L, 6.41, 381.84 r/min), medium temperature (5.12 g/L, 77.61 mg/L, 7.22, 322.29 r/min), and high temperature (2.93 g/L, 21.99 mg/L, 8.38, 287.62 r/min). Compared with the original process, the cost of flocculant can be reduced by 6.57 Yuan/t, 14.33 Yuan/t, and 20.88 Yuan/t, respectively. It was verified that the removal rates of total phosphorus, total nitrogen, and turbidity corresponding to the optimal process could reach more than 82.58%, 86.81%, and 51.86%. These findings provide scientific guidance for the flocculation treatment of pig farm biogas slurry under varying ambient temperatures.