Wastewater from the tanning industry has relatively high Cr, COD, and TSS metal pollutants. According to the regulation of the Minister of Environment of the Republic of Indonesia No. 5 of 2014 concerning the quality standard of wastewater for industrial activities, the standard quality value is 0.6 mg/L of Cr, 110 mg/L of COD, and 60 mg/L of TSS. This research aimed to determine the effect of electrode distance and voltage on reducing Cr, COD, and TSS levels in the wastewater from the tanning industry using batch electrocoagulation. The electrocoagulation method used in this research with fixed variables was the number of 2 plate electrodes and the changing variables; it was the distance between the electrodes (1, 1.5, 2, 2.5 and 3 cm) and the electric voltage (3, 6 and 9 volts). The research was conducted on a laboratory scale in batches with a capacity of 10 litres. The electrodes used were aluminium (Al) as the anode and the cathode in plates. The analysis showed that the highest percentage reduction in COD reached 88.8889% and the highest Cr reached 83.4712% occurred at a distance of 2 cm with 9 volts voltage, the highest percentage reduction in TSS reached 85.0746% with a distance of 3 cm with 9 volts voltage. From the results of this research, it could be concluded that the electrocoagulation method in the batch electrocoagulator was efficient enough to reduce the levels of Cr, COD, and TSS with variable electrode distance and electric voltage.

: Jackfruit straw is a part of jackfruit that does not experience pollination in the form of yellow fibers. Jackfruit straw has a composition consisting of 13.45% starch, 65.05% water. The potential content of jackfruit straw starch can be used as an alternative fuel, it was, bioethanol. This material can be converted to bioethanol through hydrolysis and fermentation processes. This study aimed to determine the effect of variations in the type of solvent and extraction time, used the type of solvent H2O, NaOH and NaHCO3 for starch which was then hydrolyzed and produced glucose as a raw material for making bioethanol. The initial content of jackfruit straw was carbohydrate of 11.5%, fat of 16.22% and protein of 8.38%. The first step was drying so that the jackfruit straw became powder with a moisture content <14%. Then extraction with a solvent to dissolve compounds that can interfere with the hydrolysis process such as fats and proteins. This research was conducted by extracting jackfruit straw powder into starch. Variation of the extraction process was the type of solvent (H2O, NaOH of 0.2%, and NaHCO3 of 0.2%) and the extraction time (5, 10, 15, 20, and 25 minutes) at room temperature. The results showed that the highest reducing sugar concentration of 2.16% was in the type of NaOH solvent for 25 minutes.