Effect of different buffer agents on in-vessel composting of food waste: Performance analysis and comparative study

Abstract

This study investigated the performance and feasibility for application of different buffer agent combinations, including K₂HPO₄/MgSO₄, KH₂PO₄/MgSO₄ and NaAc, in composting of food waste. The variations of temperature, pH, O₂ consumption, organic mass and ammonia release were monitored. The results showed that addition of all these three types of agents could prolong the thermophilic stage during composting. The amendments of KH₂PO₄/MgSO₄ and NaAc could increase and decrease the final pH levels, respectively. Application of K₂HPO₄/MgSO₄ and NaAc would lead to a peak daily oxygen uptake rate of 10.0 and 12.4 mg/(g·h) respectively, which were all higher than that with KH₂PO₄/MgSO₄ amendment. Similarly, the reactors with K₂HPO₄/MgSO₄ and NaAc were also associated with a higher cumulative oxygen uptake and total organic degradation rate. The amendment of NaAc resulted in a higher ammonia loss than the other two agents. More inorganic nitrogen contents were observed in the series with K₂HPO₄/MgSO₄ and NaAc. It can be concluded that K₂HPO₄/MgSO₄ additive showed the most favorable influence on composting performance. The results of this study will have important implications for developing appropriate treatment approach for food waste composting.

Keywords:

• Food waste
• composting
• buffer agent
• ammonia loss
• organic matter degradation.

Acknowledgments

This research was supported by the Natural Science and Engineering Research Council of Canada (NSERC) and National Natural Science Foundation (51109078 and 51102093). We are also grateful for anonymous reviewers for their helpful suggestions and advice.