Influence of sugar beet pulp and paper waste as bulking agents on physical, chemical, and microbial properties during green waste composting

Composting is considered to be a natural, sustainable, and highly beneficial method for solid waste disposal. The objective of this study was to investigate the two-stage composting of green waste (GW) as affected by the addition of sugar beet pulp (SBP; at 0, 25, and 35%) and/or paper waste (PW; at 0, 5, and 10%) as bulking agents. The combination of SBP and PW greatly improved the composting conditions and the final compost quality in terms of composting temperature; pH; emissions of ammonia, nitrite nitrogen, and carbon dioxide; lignocellulose degradation; microbial abundance; enzyme activities; particle-size distribution; the ratio of water-soluble organic carbon to organic nitrogen; and phytotoxicity. The optimal two-stage composting process of GW and the highest quality compost product were obtained with the combination of 25% SBP and 10% PW. This optimal combination of bulking agents produced a mature and stable final compost product in only 20 days.