(579c) Ammonia Stripping for Enhanced Biomethanization of Chicken Manure

Paper submitted to 2017 AIChE Annual Meeting, which will be held at Minneapolis, USA within October 29-November 3, 2017

Ammonia stripping for enhanced biomethanization of chicken manure

Kun Li^1,2, Ronghou Liu^1,2*, Shaofeng Cui, Ruijie Ma

1. Biomass Energy Engineering Research Centre, School of Agriculture and Biology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, P.R. China

 

2. Key Laboratory of Urban Agriculture (South), Ministry of Agriculture, 800 Dongchuan Road, Shanghai 200240, P. R. China

Abstract

Anaerobic digestion of animal manure is always with problems of ammonia inhibition, although it is characterized with high moisture, buffering capacity, organic matter and wide variety of nutrients. Ammoniacal nitrogen is generated by the biological degradation of nitrogenous matter. Optimal ammonia content guarantees sufficient buffer capacity of methanogenic medium in anaerobic digestion, thus improving the stability of the digestion process. However, high ammonia is the primary reason of digester failure because of its direct inhibition of microbial activity. In physical stripping, the desorbed component is more soluble in the gas than in the liquid state. The ammonia in gas is absorbed by sulphuric acid solution and ammonium sulphate is formed when ammonia is bubbled through sulphuric acid. In this research, the application of ammonia stripping to the digestate was tested with chicken manure. Four 2.5-L anaerobic digesters fed on chicken manure slurry were coupled to batch ammonia stripping columns and were run semi-continuously over 110 days at 37℃. The results of performance and stability were compared with control without stripping. Stripping medium was air, and the stripping columns were operated at three temperature (35, 55, 70℃). All the pH adjusted to 10, and retention time was 2 days. Results showed that temperature of the stripping column as high as 70℃ at a pH value of 10 was needed to maintain a stable anaerobic digestion of chicken manure. Under these conditions, 24.5% of the total ammonia nitrogen(TAN) was removed in two days. And the highest specific methane production (0.199 m³ CH₄/kg VS) and volumetric methane production rate (1.693 L/L▪d) were obtained at 9 g VS/L▪d. The reason for the good performance of digester R3 might be that optimal TAN concentration in R3 (coupled to column with a stripping temperature of 70℃) guarantees an adequate buffer capacity which maintains a healthy pH and allows the system to recover after a VFA shock caused by acetogenic-methanogenic imbalance. The research can provide guidance for the operation of anaerobic digesters running on chicken manure slurry.

Keywords:Ammonia removal; Batch ammonia stripping; Anaerobic digestion; Chicken manure

Kun Li , Ph. D student, majoring ecology,

Email:53772765xz@sina.com,

Phone: 0086 15021165113

Ronghou Liu, corresponding author

Professor, and Director of Biomass Energy Engineering Research Centre,

School of Agriculture and Biology,

Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, P.R. China

Email: liurhou@sjtu.edu.cn; liurhou@gmail.com; Phone: 0086 21 34205744