Coagulation and Filtration Methods on Tofu Wastewater Treatment

The tofu industry is a small industry (home industry) that produces
wastewater between 100-200 times the allowable limit and is usually
discharged directly into water bodies, thus polluting the environment. This
study aims to combine the coagulation method (stage 1) using
Polyalumunium Chloride (PAC) with filtration (stage 2) on several
variations of materials (quartz, activated carbon, and zeolite). The study
was conducted with six replications. The comparison of waste quality (BOD,
COD) was observed at each stage of the study. The SAS 9.4 was used for data
analysis, including the application of the T-test and ANOVA. The study
found that coagulation with PAC 690 mg/L reduced BOD by 51.7% and a
dose of 765 mg/L by 61.1%. In the COD parameter, the reductions were
65.84% and 67.55%. In the second stage (filtration), the reduction in BOD
was higher in activated carbon (79.33%) compared to zeolite (78.67%) and
quartz (75.46%). Activated carbon also had the most COD reduction effect
(73.22%). Although the statistical results showed significant differences in
all doses and media, the use of 765 mg / L PAC and activated carbon
filtration had the most effect on reducing BOD and COD of tofu industrial
wastewater. This research can be used as an alternative in the physical
processing of tofu industrial wastewater.