Evaluation of the effect of sodium hydroxide solution on biogas yield of anaerobic digestion of poultry waste and the digestate

The effect of adding an alkaline solution, sodium hydroxide (NaOH), in optimizing biogas and methane yield from poultry waste anaerobically was investigated in this work. Two digesters of 50 l capacity each were set up and labeled A and B. Digester A was batched with a mixture of 19 kg of PW and 19 l of water, while digester B has the same mixed volume ratio of poultry waste and water as in digester A but with the addition of 380 ml of 1 M NaOH. Daily gas yield was obtained from the two digesters for a retention period of 30 days; the temperature and pH were also recorded. The peak yield from digester A was recorded on day 23 to be 0.0392 m3, while digester B peak yield of 0.0522 m3 was recorded on day 18. The cumulative biogas yields at the end of the retention period were 0.5511 m3 and 0.6070 m3, respectively, for both digesters. The coefficient of correlation R2 between the gas yields of the two samples is 0.9657. The biogas obtained from the two setups was analyzed with digester B (poultry waste + water + 380 ml of 1 M NaOH) having an appreciable methane yield of 3.03% than digester A.