Wastewater from Tapioca Starch Manufacturers Affecting Growth and Yield of Sugarcane

Abstract

The severe drought crisis in Thailand, which has been intensifying since the end of 2019 continuously resulting in water shortages. Therefore, utilizing industrial wastewater for beneficial purposes has been one of the strategies to address the drought problem. This research aimed to study the impacts of effluent wastewater from tapioca starch manufacturers on the growth and yield of sugarcane, comparing it with natural water and rainfed conditions. The quality of the effluent wastewater from the tapioca starch factory was assessed, revealing that the levels of total suspended solids (TSS), total dissolved solids (TDS), initial biochemical oxygen demand (BOD), and chemical oxygen demand (COD) exceeded the prescribed standard for discharge of tapioca starch effluent wastewater. The growth and biomass of sugarcane var. KhonKaen 3 were examined to investigate the effect of supplying effluent wastewater. The experimental design of the plot followed a randomized complete block design (RBD) with four replications and three treatments. The treatments included: 1) Supplemental water using factory effluent wastewater, 2) Supplemental water using natural water, and 3) No water (rainfed condition serving as the control) weekly measurements of crop water uptake for sugarcane var. KhonKaen3 was recorded and calculated based on crop water requirements handbook. The effect of water supply on sugarcane cultivation revealed no significant differences in growth and sugarcane yields including stem height (257.8-270 cm.), length of internode (8.38-8.94 cm.), number of internodes/stem (26.83-27.08 internodes/stem), weight/stem (1.85-1.87 kg/stem), and yield/rai (16.96-17.30 tons/rai) between the supply of factory effluent wastewater and natural water supply. The application of rainfed supply resulted in a decrease in both growth and sugarcane yield. However, the percentage of CCS (commercial cane sugar) exhibited no statistically significant difference across the treatments (12.38-13.40 °Brix). After harvesting, the accumulated levels of toxic substances and heavy metals in sugarcane and soil samples remained within the acceptable standard limits. The analysis of soil samples revealed relatively elevated levels of nutrient element accumulation, including potassium, calcium, magnesium, manganese, and iron, which remained below the standard value. Nonetheless, the extent of toxic substance accumulation in the soil is contingent upon the duration of the plantation period. In primary conclusion, the findings suggest that the effluent wastewater from the tapioca starch industry holds promise for plant cultivation during a drought crisis, as it does not exhibit any significant adverse effects on plant yields and soil quality.