Sequencing Batch Reactor(SBR) experiments for organics and nutrients removal have been conducted to find an optimum anaerobic/anoxic/aerobic cycling time and evaluate the applicability of oxidation-reduction potential(ORP) as a process control parameter.
In this study, a 6 ℓ bench-scale plant was used and fed with night-soil wastewater in K city which contained TCODcr : 10,680 ㎎/ℓ, TKN : 6,893 ㎎/ℓ, NH_4^+ -N : 1,609 ㎎/ℓ, PO_4^3- -P : 602 ㎎/ℓ on average. The cycling time in SBRs was adjusted at 12 hours and 24 hours, and then certainly included anaerobic, aerobic and anoxic conditions. Also, for each cycling time, we performed 3 series of experiment simultaneously which was set up 10 days, 20 days and 30 days as SRT.
From the experimental results, the optimum cycling time for biological nutrient removal with night-soil wastewater was respctively 3hrs, 5hrs, 3hrs(anaerobic-aerobic-anoxic). Nitrogen removal efficiency was 77.9%, 77.9%, 81.7% for each SRT, respectively. When external carbon source was fed in the anoxic phase, ORP-bending point indicating nitrate break point appeared clearly and nitrogen removal efficiency increased as 96.5%, 97.1%, 98.9%. Phosphate removal efficiency was 59.8%, 64.5%, 68.6% for each SRT. Also, we finded the applicability of ORP as a process control parameter in SBRs.