Abstract
In this study, the anaerobic ultimate biodegradability and multiple decay rate of organic matter were evaluated according to various salt concentrations in seafood processing wastewater. The evaluation was also performed with various types of anaerobic bacteria and S/I (substrate/inoculum) ratios. After the S/I ratio was fixed at 0.9, the ultimate biodegradability values of the anaerobic digested sludge and granular sludge were became 72.0% and 92.0%, respectively. The multiple decay rate coefficients ($k_1$) coefficients of the anaerobic digested sludge and granular sludge were $0.0478{\sim}0.1252\;day^{-1}$ and $0.0667{\sim}0.1709\;day^{-1}$, respectively. The optimum S/I ratio of the seafood wastewater, which was determined based on the ultimate anaerobic biodegradability and gas production, was 0.9. The organic matter removal rate never became less than 85.0% under a 3,000 mg/L chloride concentration. The multiple decay rate coefficients ($k_1$) were $0.1603{\sim}0.1709\;day^{-1}$ under $3,000\;mgCl^-/L$, and $0.0492{\sim}0.0760\;day^{-1}$ in more than $6,000\;mgCl^-/L$. The multiple decay rate coefficients ($k_2$) were $0.0183{\sim}0.0348\;day^{-1}$ under $6,000\;mgCl^-/L$, and $0.0154\;day^{-1}$ at $9,000\;mgCl^-/L$. With increasing chloride concentrations, the reaction rate ($k_1$, $k_2$) and ratio of the rapidly degraded organic matter ($S_1$) decreased.
본 연구는 해산물 가공폐수를 대상으로 혐기성 미생물, S/I ratio (substrate/inoculum)와 염분농도에 따른 혐기성 최종 생분해도를 평가하였다. S/I ratio 0.9에서 혐기성 소화슬러지와 입상슬러지의 최종 생분해도는 각 72.0, 92.0%로 조사되었으며, 다중분해속도 상수 $k_1$은 소화슬러지가 $0.0478{\sim}0.1252\;day^{-1}$, 입상슬러지는 $0.0667{\sim}0.1709\;day^{-1}$로 조사되어 입상슬러지가 해산물 가공폐수의 혐기성 처리에 적합하였다. 혐기성 최종생분해도 실험을 통해 산정된 최적 S/I ratio는 0.9였으며, 염분농도에 따른 생분해도 실험 결과, $3,000\;mgCl^-/L$ 이하에서 85% 이상의 유기물 제거효율을 나타냈다. 다중분해속도 상수 $k_1$은, $3,000\;mgCl^-/L$ 이하에서는 $0.1603{\sim}0.1709\;day^{-1}$, $6,000\;mgCl^-/L$ 이상에서 $0.0492{\sim}0.0760\;day^{-1}$로 산정되었으며, $k_2$는 $6,000\;mgCl^-/L$ 이하에서는 $0.0183{\sim}0.0348\;day^{-1}$, $9,000\;mgCl^-/L$에서는 $0.0154\;day^{-1}$로 조사되어, 반응속도 상수($k_1$, $k_2$)는 $Cl^-$ 농도가 증가할수록 감소하였으며, 빠르게 분해되는 유기물 비율($S_1$)과 분해속도 또한 감소시키는 것으로 조사되었다.