Impact of Alkaline H2O2 Pretreatment on Methane Generation Potential of Greenhouse Crop Waste under Anaerobic Conditions

Abstract

This paper intended to explore the effect of alkaline H2O2 pretreatment on the biodegradability and the methane generation potential of greenhouse crop waste. A multi-variable experimental design was implemented. In this approach, initial solid content (3–7%), reaction time (6–24 h), H2O2 concentration (1–3%), and reaction temperature (50–100 °C) were varied in different combinations to determine the impact of alkaline H2O2 pretreatment. The results indicated that the alkaline H2O2 pretreatment induced a significant increase in the range of 200–800% in chemical oxygen demand (COD) leakage into the soluble phase, and boosted the methane generation potential from 174 mLCH4/g of volatile solid (VS) to a much higher bracket of 250–350 mLCH4/gVS. Similarly, the lignocellulosic structure of the material was broken down and hydrolyzed by H2O2 dosing, which increased the rate of volatile matter utilization from 31% to 50–70% depending on selected conditions. Alkaline H2O2 pretreatment was optimized to determine optimal conditions for the enhancement of methane generation assuming a cost-driven approach. Optimal alkaline H2O2 pretreatment conditions were found as a reaction temperature of 50 °C, 7% initial solid content, 1% H2O2 concentration, and a reaction time of six h. Under these conditions, the biochemical methane potential (BMP) test yielded as 309 mLCH4/gVS. The enhancement of methane production was calculated as 77.6% compared to raw greenhouse crop wastes.

Keywords

• alkaline H2O2 pretreatment
• breakdown of lignocellulosic structure
• greenhouse crop waste
• methane generation
• process optimization