Abstract:
The aim of this research is to find out degradation contamination level of tofu waste water usage effect of Azolla pinnata as a biofilter, is later than planning unit processing of waste for middle industry, planning operating and levying cost of waste water processing unit. Research method which used is quantitative and qualitative method. Besides to determine criterion of design for facility for the unit of processing tofu waste water, like filtration, precipitation, and oxidation ditch, and channel between basin. The next is calculation levying and operation cost of tofu waste water processing unit.
Planning of unit processing of waste water from calculation result got channel 10 m length, 0,5 m width, and 0,65 m depth, for sedimentation basin 1 m length, 1 m width and 2 m depth. Need 6 oxidation ditch for the one which 8 m length, 3 m width, and 1 m depth. Azolla pinnata needs 6 days for tofu waste water degradation optimally which detention time for each ditch is 2 days.
The result of calculation with density of Azolla pinnata oxidation ditch counted 20 g/cm2, can degrade rate of BOD from 2120 mg /l become 75,69 mg/l (96,42%), value of COD 1012,8 mg/l become 192,81 mg/l (80,96%), value of N-Total alight from 24,93 mg/l become 4,9 mg/l (80,34%), P-Total of value 17,9 mg/l become 3,97 mg/l (77,82%), and pH of value 4,28 experiencing of improvement become 8,06 ( 88,31%), and also DO from 1,4 mg/l become 2,56 mg/l (82,85%). Base on cost analysis got result that the development unit processing of tofu waste water, factory owner is encumbered expense for fixed capital equal to Rp 14.777.750,50. the biggest expenditure of fixed capital is the expense of making oxidation pool, that is equal to Rp 11.315.520,00. At operational expenses processing of tofu waste, factory owner also will encumbered the expense of equal to Rp 17.567.000,00 / year. The biggest expenditure of operating expenses is labor cost that is Rp 13.560.000,00 / year.
