This study explored effects of a sludge-based biochar addition on nitrogen removal of membrane bioreactor (MBR) for wastewater treatment. The membrane fouling reduction by the biochar addition was also investigated. A dose of 3 g/L of the biochar was applied to an MBR (i.e., BC-MBR) and treatment efficiencies of organic matter and nutrient were analyzed. The MBRs with powdered activated carbon (i.e., AC-MBR) and without any additives were also operated in parallel. The average removals of COD and TN were improved with the biochar addition compared to those with the control MBR. Interestingly, operational duration was also increased with biochar addition. The CLSM analysis revealed that biomass amounts of BC-MBR and AC-MBR were reduced by more than 40%, and thickness of the biofilm attached to the membrane surface also was decreased. The physical properties of biochar surfaces were compared with a commercial powdered activated carbon. The specific surface area with 38 m2/g and pore volume with 0.13 cm3/g of the biochar were much smaller than those of the powdered activated carbon, which were 1100 m2/g and 0.67 cm3/g, respectively. Manufacturing conditions for the biochar production needs to be further investigated for enhancing physical properties for adsorption and biological improvement.

Phosphorus is a vital resource for sustaining agriculture and nutrition, but a limited non-renewable resource. Thus, the recovery of phosphorus from waste activated sludge(WAS) was attempted by microwave heating and magnesium ammonium phosphorus(MAP) crystallization. Polyphosphate-accumulating organisms(PAOs) in WAS release phosphate from the cell when they are exposed to high temperature environments. Microwave heating caused phosphorus and ammonia to release from WAS. The amount was increased with increasing temperature, showing that 88.5% of polyphosphate present in the cells were released in the form of phosphate at 80oC. A similar result was also observed in the release of ammonia. On the other hand, both phosphorus and ammonia were crystallized with magnesium, and then was harvested as MAP. Phosphorus recovery rate reached almost 97.8%, but the ammonia was about 13.4%. These results cleary indicate that phosphorus could be recovered from WAS using a physiological trait of PAOs. Heavy metal analyses also show that the MAP crystal is useful and safe as a phosphorus fertilizer.

Chemical batch tests were conducted to investigate the amount of nutrients that were released from the wasted activated sludge during microwave heating. For this study, three types of activated sludge were obtained from A2/O, MLE and oxidation ditch (OD) processes. Polyphosphate-accumulating organisms in the activated sludge have a unique trait: they releases phosphate from the cell when they are exposed to high temperatures. The sludge obtained from the A2/O process released the largest amount of phosphate, followed by those from the MLE and OD processes. The release of phosphate increased with increasing polyphosphate content in the sludge under strongly alkaline or acidic conditions. Furthermore, ammonia and heavy metals were released with phosphorous. The largest amount of ammonia was observed from the sludge obtained from the MLE process. The release of heavy metals strongly depends on the pH conditions. Therefore, the chemical analysis results strongly suggest that both phosphorus and ammonia react with Mg2+ or Ca2+ to form metal complexes such as magnesium ammonium phosphate or hydroxyapatite under alkaline conditions.

The objectives of this research was to evaluate the anaerobic digestibility of waste activated sludge (herein after WAS)and waste beverages (herein after WB) in beverages manufacturing industry using actual plant under various conditions.In this study, anaerobic digestion with WAS and WB were evaluated according to different operating conditions. As thebasis operating conditions for anaerobic digestion, the reaction temperature was controlled at 35 and hydraulic retentiontime 30 days. WAS and WB were mixed at the ratio of 1:0, 9:1, 8:2, 7:3, 5:5, Respectively. The organic loadingrate (herein after OLR) was maintained less than 0.5kgVS/m3·day. Biogas productivity in accordance with VS was fedat the each mixing ratio with WAS and WB was increased from 0.92Nm3/kg VSfeed to 1.28Nm3/kg VSfeed, except mixingratio 5:5 (0.19Nm3/kg VSfeed). Also Biogas productivity in accordance with VS was removed at the each mixing ratiowith WAS and WB was increased from 1.13Nm3/kg VSrem to 1.81Nm3/kg VSrem, except mixing ratio 5:5 (0.35Nm3/kg VSrem). It was judged that pH was reduced with WB addition. From the results, it was judged that anaerobic digestionusing WAS and WB could be feasible.

The objectives of this research was to evaluate the anaerobic digestibility of waste actizvated sludge (WAS) and wastebeverages in beverages manufacturing industry using BMP test under various conditions. Also, the effects of physical(ultrasonic) and biological (lactobacillus) solubilization process on anaerobic digestibility of WAS were thoroughlystudied. The soluble chemical oxygen demand (SCODCr)/total chemical oxygen demand (TCODCr) ratio of WAS was 0.15but the SCODCr/TCODCr ratio after solubilization was increased 17.5% by ultrasonic, 18.8% by lactobacillus respectively.The results of BMP test, methane gas productivity as mixing ratio of WAS and waste beverages were 156ml CH4/gCODCr,164ml CH4/gCODCr and 182ml CH4/g CODCr, respectively 9:1, 8:2, 7:3 before the solubilization of WAS. As themixing ratio of waste beverages increase, VFAs concentration and methane productivity was increased. Also, methanegas productivity as mixing ratio after the solubilization of WAS using ultrasonic and lactobacillus was increased3.3~11.3%, 11.1~15.2% respectively. From the results, it was judged that anaerobic digestion using WAS and wastebeverages could be feasible.

현재 우리나라의 슬러지 발생량은 지속적으로 증가하는 추세이며, 해양매립이 금지됨에 따라, 슬러지의 처리방법과 활용방안이 시급해져 새로운 방법을 모색할 필요가 있다. 이 연구에서는 하수 처리 시 발생하는 잉여슬러지의 탈수성을 증대시켜 슬러지 케이크를 감소시키기 위해 초음파를 적용하였다. 초음파를 액체에 발사하면 액중에 수축과 팽창이 교대로 일어나며 수 만개 이상의 미세한 공동이 발생된다. 이 공동이 폭발하면서 발생한 에너지를 슬러지의 입자 파괴에 이용하여 슬러지의 탈수성을 증대시키고자 하였다. 이번 연구에서 사용된 슬러지는 김포하수처리장에서 채취한 탈수 전 슬러지이며 하수슬러지 7L에 초음파 조사시간(5min, 10min, 20min, 30min, 50min, 60min)에 조사강도 154W, 308W를 가하였다. 일반적으로 초음파 조사시간이 길어질수록 CST가 증가하는 경향을 보였다. 그러나 조사한 슬러지에 응집제를 첨가시 초음파 강도와 조사시간에 따른 CST 결과 154W에서 조사시간 5분, 10분일 때 CST가 가장 낮게 측정되었다. 또한 초음파 조사시간에 따른 원심분리실험을 실시하였다. 조사시간 5min, 10min일 때를 조사하지 않은 슬러지와 실험을 실시한 결과, 초음파에 조사된 슬러지가 초기 침하되는 속도가 더 빠르며, 최종침하량도 더 빨리 도달했다. 연구결과 초음파조사시간과 초음파 강도가 탈수성에 큰 영향을 주었다. 탈수성의 직접적 효과를 보기 위하여 조사시간 5~10min, 초음파 강도 154W를 가해야한다. 이를 잉여슬러지의 탈수능 향상에 도입시 유용하게 사용될 수 있을 것으로 기대된다.