Effect of Alkaline Pretreatment on the Biogas generation efficiency of Water Hyacinth

Prétraitement alcalin et potentiel méthanogène de la jacinthe d’eau

Abstract

Water hyacinth, known as Eichlornia crassipes and considered an invasive aquatic plant, has spread worldwide. It now poses a threat to aquatic ecosystems. In Burkina Faso, the most common method used to fight this invasive plant is mechanical removal during its growth phase. This method produces a large amount of plant material that could be converted into biogas, a renewable energy source. Additionally, the end result of the process, referred to as digestate, has the potential to be used as a fertiliser in agriculture.

However,  the  lignocellulosic  structure  of  the  plant  significantly  hinders  its

biodegradability. To address this issue, the current study examines the effect of

potassium hydroxide (KOH) pretreatment on biogas production. In an initial screening

process, KOH concentrations of 2–4% were tested to gauge their impact on the pH of

the samples. Based on these results, three pretreatment concentrations were chosen

for further study: 0.6%, 0.8% and 1%. These pretreatments were applied to crushed

water hyacinth biomass, followed by mesophilic anaerobic digestion for 22 days. The

findings indicated that the sample treated with 0.8% KOH produced the highest

volume of biogas, totalling 3,550 ml. Despite this, the methane content was

surprisingly the lowest (325.25 ml). The samples that produced the most methane

were the reference sample and the 1% KOH-treated sample, with methane contents of

607.4 ml and 596.7 ml, respectively.