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

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.