Effect of additives on NH3 and H2S emissions during kitchen waste composting

Abstract: In recent years, the urbanization rate in China is steadily increasing, and the production of the municipal solid waste is also increasing. As the precious resource among the municipal solid waste, the kitchen waste composting has received widespread attention. In order to reduce the odor emission in the composting process of kitchen waste, this study investigated the effect of additives on the odor emissions (ammonia and hydrogen sulfide) of kitchen waste composting. Two control treatments were set in the study, the CK1 used pure kitchen waste to compost, and the mixture of kitchen waste and 15% (wet weight) of cornstalks was CK2. On the basis of CK2, 3 types of additives were used to compost kitchen waste, and they were adsorbent (activated carbon + zeolite, bentonite), surfactant (β-cyclodextrin, rhamnolipid) and composting inoculants (bacteria agent for municipal solid waste (SUKAZYE), saccharomycetes). Each additive had 3 kinds of adding amounts, and the monitoring substance was ammonia and hydrogen sulfide. The effects of different additives with different adding amounts on the emission of ammonia and hydrogen sulfide from the kitchen waste composting were investigated under laboratory simulation conditions, and the compost was finished in the jars (the volume was 1 L) under aerobic conditions. The results showed that compared with the kitchen waste compost, adding cornstalks could reduce the ammonia emission by 7%-23%, and reduce the hydrogen sulfide emission by 38%-50% during the composting process. Based on the treatment CK2, adding 2% of activated carbon + zeolite showed the best control effect of ammonia emission, and it could reduce the ammonia emission by 84% compared with the CK1 and by 79% compared with the CK2. But when it came to the control effect of hydrogen sulfide, neither activated carbon + zeolite nor bentonite showed a good performance. The results of the 2 kinds of surfactant showed that β-cyclodextrin and rhamnolipid had little effect on the emissions of ammonia, but adding 1% of the β-cyclodextrin could reduce the hydrogen sulfide emission by 35% compared with the treatment CK2. The results of the 2 kinds of composting inoculants showed that adding 0.4% of bacteria agent for municipal solid waste (SUKAZYE) could reduce the ammonia emissions by 72% and reduce the hydrogen sulfide emission by 33% compared with the treatment CK2. In summary, the addition of corn straw can effectively reduce the hydrogen sulfide emission and ammonia emission during the composting process of kitchen waste. On the basis of adding corn straw, adding activated carbon + zeolite or bacteria agent for municipal solid waste (SUKAZYE) can both effectively reduce the emissions of ammonia in the composting process of kitchen waste and the emission reduction rate can reach more than 70%. The addition of β-cyclodextrin and bacteria agent for municipal solid waste (SUKAZYE) can reduce the emissions of hydrogen sulfide in the composting process of kitchen waste, and on the basis of adding straw they can reduce the hydrogen sulfide emission by more than 30%. The results can supply a reference for selecting additives to control odor emissions during kitchen waste composting.