THE EFFECT OF STARTER RATIO ON TOFU-PROCESSING WASTEWATER FERMENTATION INTO FERTILIZER

The process of tofu manufacturing produces solid (slurry) and liquid wastes with high protein content. Tofu-processing Wastewater can be used as the primary material for liquid NPK fertilizer production. The process of converting tofu-processing wastewater into liquid fertilizer was simple and requires a short fermentation time. The fermentation process was carried out by mixing of EM 4 (starter for fermentation liquid), alcohol as solvent and organics matter. The selection of organic matter that is used as the primary ingredient of liquid fertilizer would affect the content of N, P and K substances in the product. Banana peel and cabbage are organic matter with a high calcium and phosphorus content. This research was conducted to determine the effect of the addition ratio of cabbage and banana peel to time duration of fermentation on the tofu- wastewater processing into liquid fertilizer. The results showed that increasing the ratio of cabbage to the starter increased the levels of N and P along with the length of fermentation time. However, increasing the cabbage ratio in the starter causes a decrease of K in liquid fertilizer