การศึกษาสภาวะที่เหมาะสมในการปรับสภาพกากมันสำปะหลังด้วยวิธีการใช้น้ำร้อนและไฮโดรไลซีสให้ได้น้ำตาลเพื่อการผลิตก๊าซมีเทน

Thailand has been recorded as the global highest cassava starch exporter. Within the year of 2015–2019, Thailand exported cassava starch about 3.8–4.2 million tons per year, thus a large amount of cassava pulp (CP) as a major agro-industrial byproduct from cassava starch manufacturing was massively generated. CP is generated during the step of fiber and pulp separation after starch extraction in cassava starch processing. The production of one ton cassava starch generates approximately 2.5 ton of CP with 70–80% moisture content. By calculation from these data, a huge amount of CP (9.5–10.5 million tons) was annually generated. Improper CP treatment and management can cause air pollution from the unpleasant odor of decayed CP and the contamination of CP leachate to the environment around the factory. Starch is the main polysaccharide in CP, consisting of 55– 75% starch. Non-starch polysaccharide contains with approximately 15–17% cellulose, 4–6% hemicellulose, 1–4% lignin, and a number of minor organic compounds such as crude fat and crude protein. Considering to its high organic content, CP has gained increasing interest to be utilized as a low-cost raw material for various valuable products such as methane production. The CP structure shows that starch granules are trapped inside cell wall. In this research, we have idea to develop the process for destructive lignocellulose by pretreatment before hydrolysis. Pretreatment using liquid hot water (LHW), also known as a hydrothermal or autohydrolysis process, had gained attention due to no chemical used, with no or minor erosion to the equipment, and short reaction time. One challenge of CP utilization as feedstock for biomethane production is to disrupt the cellular matrix and release the entrapped starch granules from the complex lignocellulosic structure for easy access by anaerobic microbial digestion and improvement of hydrolytic enzyme. To solve this problem, pretreatment is generally used to accelerate and increase the rate of lignocellulosic hydrolysis for enhancing methane production. From literature reviews, LHW pretreatment shows high performance in removal of hemicellulose and recovery of hemicellulose-derivative sugar but generating low amount of inhibitors production, such as furfural (FF) and hydroxymethylfurfural (HMF), comparing to other pretreatment methods. Moreover, LHW pretreatment has been considered as one of the most potential technologies to apply in the pilot and industrial scale for lignocelluloses fractionation and breaking down cell wall structure. Thus, LHW pretreatment is a promising method on cell wall disruption and starch solubilization with result in high total sugar recovery and low inhibitors production. It will enhance degradation of lignocelluloses and methane production in anaerobic digestion (AD). Furthermore, no information from literature search has been reported for CP pretreatment by LHW prior AD for methane production.

To accelerate lignocellulosic CP degradation and enhance biomethane production from CP in this research, the study will optimize liquid hot water (LHW) pretreatment and hydrolysis methods of hydrolysate and pretreated cassava pulp on sugar production from cassava pulp. The experiments will be carried out into 3 parts. In the first part, the optimization of LHW on cassava pulp will be performed to minimize inhibitors and obtain high sugar recovery in hydrolysate. The expected result after LHW pretreatment will be 1) all starch and hemicellulose in cassava pulp will solubilize in hydrolysate and 2) cellulose and lignin will remain in solid residue. In the second part, starch in clear hydrolysate and cellulose in solid residue will be hydrolyzed and converted into glucose by enzymatic hydrolysis. Finally, biomethane production from LHW-pretreated CP at optimum condition and non-pretreated CP will be studied.

          This study will also meet the concept of close to zero waste by developing the production of methane and utilization of CP-solid waste. It is in the platform of BCG as following: bioeconomy (competition technique/technology and methane as valuable renewable energy), circular economy (Bioresource circular), and green economy (treatment, waste reduction, pollution mitigation, environmental conservation) including increase of eco-efficiency by reduction of resources, fossil fuel, GHG (CO₂, NO_x, SO_x) as shown in Figure of biogas cycle.

Biogas Cycle (Bioresources conservation)