Optimization of Biochemical Treatment Process for Fish Feces Based on Nitrogen Recycling

In order to explore biochemical treatment process of fish feces suitable for efficient recycling of nitrogen in fish and vegetable symbiosis system, anaerobic and aerobic processes were set up for biochemical treatment of fish feces．Three reaction temperatures and three fish feces TS concentrations were set for each process to study change rule of nitrogen in fish feces after different processes and impact of fish feces on lettuce growth．Results showed that ratio of ammonia to nitrate in fish dung liquid after anaerobic treatment increased, and ratio of ammonia to nitrate in fish dung liquid after aerobic treatment decreased to less than 1.0．The best growth rate of lettuce was cultivated for fish dung after aerobic treatment at 35.0 °C with TS concentration was from 3.0% to 3.5%, indicating that the most suitable biochemical treatment process for lettuce growth was TS concentration of raw fish dung from 3.0% to 3.5%, and aerobic treatment at 35.0 °C for 10 days．