Effect of surfactant addition on disperser disintegration of water hyacinth: a new insight to overcome the inhibitory effects of lignin on methanogenesis and improve the energy and economic aspects

Abstract

The technology for disperser-mediated disintegration (DMD) of water hyacinth biomass (WHB) (Eichhornia crassipes) has been limited by its high energy requirements, aggregation of the biomass, and the binding of lignin to methanogenic enzymes during the biomethanation process. Thus, these limitations could affect the overall efficiency of the process. Moreover, it is questionable whether cost-effective biomethanation via the DMD process can be achieved. The main aim of this work is to determine whether a combinatorial pretreatment can enhance the biomass solubilization with lower energy input, and reduce the issue of biomass aggregation and lignin inhibition leading to a greater economic output. The combinatorial chemo-mechanical pretreatment combines two different pretreatments by integrating a surfactant, sodium dodecyl sulfate (SDS), with a mechanical pretreatment induced by a disperser. The outcome of the study revealed that this combinatorial pretreatment reduced the specific energy input of the DMD process (1230 kJ kg⁻¹ Total Solids (TS)) to 184.5 kJ kg⁻¹ TS in the SDMD (surfactant-disperser-mediated disintegration) process. A higher solubilization of 23% was achieved in SDMD when compared to DMD (9.5%). A greater methane production of 0.35 L g⁻¹ chemical oxygen demand (COD) was documented in SDMD due to surfactant addition, which prevents the adsorption of enzymes secreted by methanogens onto the lignin. The energy and economic analysis revealed that a higher net profit of 2.3 USD per ton was achieved in SDMD when compared to DMD.