Effects of different composting methods on Enteromorpha: Maturity, nutrients, and organic carbon transformation

Abstract

This study investigated the composting performance of Enteromorpha for product maturity and organic carbon transformation under membrane-covered aerobic composting and windrow composting. Meanwhile, the effects of adding mushroom waste as an additive on the Enteromorpha composting process performance were evaluated. Results show that Enteromorpha was highly compostable and had low phytotoxicity under different composting techniques after 60 days. Each method's high temperature (>50 °C) can maintain for more than 5 days during the composting process of Enteromorpha, which meets the Chinese national standard for organic fertilizer production. Moreover, the highest GI (113%) was obtained by the forced ventilation treatment with mushroom waste, which was mainly achieved by adjusting the raw materials of compost. The addition of mushroom waste could improve the polymerization of humic substances and maintain nutrients, while the Enteromorpha alone composting had a serious nutrient loss phenomenon no matter what method was adopted. Regardless of composting conditions, the rapid decline of cellulose, fat, and starch content occurred during the high-temperature period. In addition, the maturity of Enteromorpha compost was mainly related to the degradation of organic matter. Forced ventilation can reduce the phytotoxicity of Enteromorpha composting better than windrow composting. The results can provide theoretical basis and measures for the practical application of Enteromorpha treatment and the directional control of compost maturity.