Abstract:
This research focused the studies on the addition of 2 different forms of iron ; ferric ion and ferric chelate into the Anaerobic Baffled Reactor (ABR). The reactor volume of 16 liters was separated into 4 compartments with equal volume of 4 liters. Both different forms of iron were added with 3 trial ratios of Fe³+: COD as 0.1, 1.0 and 10.0 mg-Fe/g-COD, which is expected to be sufficient for the anaerobic process reaction. The experiment reactor was divided into 3 systems, (1) the control system; (2) the system of ferric ion adding by using ferric chloride and ; (3) the system of ferric chelate adding by using ferric citrate. Those three reactor systems were operated simultaneously under continuous feeding by synthetic wastewater of the COD = 3,600 mg/l, NO₃-N = 300 mg-N/l and SO₄ = 300 mg-SO₄/l. A hydraulic retention time (HRT) was 2 days and an organic loading rate (OLR) is 1.8 kg-COD/m³-day. The results showed that the reactors with iron adding for both two iron forms indicated no different results. As for the removal efficiency in the three system were likely in the same way, which the COD and nitrate removal efficiency were approximately 90 percent and Ammonia was formed in the system by Dissimilatory Nitrate Reduction to Ammonia (DNRA) while the efficiency of sulfate removal through sulfate reduction were approximately 50 percent in the first trial ratio of 0.1 mg-Fe/g-COD and increased to approximately 80 percent in second trial when increase the Fe³+: COD for ten times to 1.0 and 10.0 mg-Fe/g-COD. It can be concluded that the iron form did not result to make a difference in denitrification and sulfate reduction. However, increasing the Fe³+: COD ratio was increased the sulfate removal efficiency and enhanced DNRA process.