• 한국환경보건학회지
• /
• 제25권3호
• /
• pp.23-28
• /
• 1999

Phosphate removal through adsorbent, such as activated alumina, powdered aluminum oxide, flyash, blasted furnace slag and other materials, is commonly and widely practiced. The purpose of this study was to improve the removal efficiency of phosphorus in waste sludge earned at seafood processing factories. To investigate the utility and the feasibility of this sludge disposal process, experiment was carried out with a batch process. As a result, phosphate removal appears to increase with increasing adsorbent does, but shows no changes at an adsorbent does over 5g/l. With increasing ratios of initial phosphate concentration to adsorbent does, the amount of removed phosphate is increased while phosphate removal(%) is decreased. Wasted sludge, treated with zinc chloride chemically, represented a better efficiency than the untreated activated sludge and zinc chloride itself, when they reacted with phosphate solution.

• 한국폐기물자원순환학회지
• /
• 제35권8호
• /
• pp.701-708
• /
• 2018

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 $A_2/O$, 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 $A_2/O$ 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 $Mg^{2+}$ or $Ca^{2+}$ to form metal complexes such as magnesium ammonium phosphate or hydroxyapatite under alkaline conditions.

• 한국물환경학회지
• /
• 제22권2호
• /
• pp.264-270
• /
• 2006

In this research, volume reduction of activated sludge using electrolysis was studied to find an optimum condition using lab scale experiments. Wasted sludge was treated by electrolysis with controlling current density, chloride concentration, electrode distance, and reaction time. Volume of return sludge was reduced by 9.79% in average while maximum was 16.7%. Sludge volume reduction efficiency was affected by current density and reaction time. It was reversely proportional to the electrode distance. Especially current density was effective on the system performance significantly. Electric conductivity, salinity and COD were increased by electrolysis implying sludge disintegrated and converted to COD in part. An empirical equation for total solid removal efficiency by electrolysis was proposed by multiple linear regression analysis as: $TS_{rem}$(%) = 5.534 ${\times}$ current density (A/l) + 0.178 ${\times}$ reaction time (m) + 2.758.

• 한국물환경학회지
• /
• 제20권4호
• /
• pp.346-351
• /
• 2004

Because of being produced a great deal of excess sludges from biological wastewater treatment process, the subject regarding treatment and disposal of them has been significantly handled in real plants. It should be considered the alternative treatment with easy operating and cost effective process in rural areas. For the thickening of wasted activated sludge from small scale wastewater treatment facilities, thus, the provisional sludge thickening system was developed by the application of mesh filter module. Three meshes with different pore size(100, 150, $200{\mu}m$) were prepared for filter modules that were used to withdraw effluent from thickening system. A filter module with $100{\mu}m$ mesh was chosen as the most effective thickening material in the viewpoint of volume reduction and effluent quality: the volume reductions of initially injected sludge with 3,600 mg/L and 9,100 mg/L were 95% and 85%, respectively, and the filtered effluents were enough good to be shown below 1.0 mg/L of SS and 1.0 NTU of turbidity. Since the filtration of thickening was influenced by the cake layer formed on mesh filter module and this system was operated in the combination of sludge thickening with gravity settling, the filter modules with smaller pore size and the larger floc size were required for long term operation safely.

• 한국물환경학회지
• /
• 제20권4호
• /
• pp.327-332
• /
• 2004

This study was carried out to examine the effect of gamma irradiation on the physico-chemical characteristics and ultimate anaerobic biodegradability of sewage sludge. The results found that the solubilization rates of SCOD in wasted activated sludge(WAS) and thickened sludge(T-S) with gamma irradiation of 3kGy were 8 times and 7 times greater than these of the raw WAS and T-S without the irradiation, respectively; each soluble concentration protein were 4 times and 3 times greater than these of the raw WAS and T-S; each soluble carbohydrate concentration was 8 times and 6 times greater than these of the raw WAS and T-S. The ultimate anaerobic biodegradabilities of WAS and T-S with gamma irradiation were 51 % and 50%, which corresponds to each 8% and 10% greater than these of the raw sludges. Approximately 83% and 81% of the each biodegradable substrates in the irradiated WAS and the T-S were degraded within 11 days with the first order decay rate coefficients, $k_1$ that ranged $0.143{\sim}0.164day^{-1}$ for WAS and $0.134{\sim}0.152day^{-1}$ for T-S. Based on the results, it can be concluded that when irradiated with gamma the solubilization of sewage sludge greatly increases resulting in substrates suitable for the subsequent biological treatment processes.

• Korean Chemical Engineering Research
• /
• 제52권4호
• /
• pp.503-515
• /
• 2014

최근 하수처리장의 질소 및 인 방류수 수질기준이 강화되고 슬러지의 해양투기가 금지됨에 따라 기존 표준활성슬러지공법의 고도처리공법으로의 증설 및 새로운 하수슬러지 처리공법에 대한 환경성, 경제성 평가의 필요성이 증가하고 있다. 이러한 고도처리 및 슬러지 처리공법은 운영 단계뿐만 아니라 건설, 폐기를 포함한 전과정에 걸쳐 환경 전반에 영향을 미치며 경제적 비용을 소모하므로, 본 연구에서는 건설에서부터 폐기까지의 전과정을 고려하여 고도처리공정 및 슬러지 처리 공법의 환경성, 경제성을 평가하고자 한다. 고도처리공법으로 Anaerobic/Anoxic/Oxic ($A_2O$), Bamard Denitrification Phosphate (Bardenpho), Virginia Initiative Plant (VIP), Modified University of Cape Town (MUCT) 공법을, 슬러지 처리공법으로는 매립, 소각, 퇴비화를 선정하였다. 각 공법에 따른 환경성, 경제성 평가를 위하여 International organization for standardization (ISO)에서 제시하는 가이드라인을 따라 전과정평가를 수행하였으며, 전생애비용을 산정 비교하였다. 각 고도처리 공법에 대한 평가 결과, 환경영향 측면에서는 운영 단계에서의 생물학적 처리로 인한 온실가스 배출이, 경제성 측면에서는 운영 단계에서의 전력소모가 가장 많은 영향을 미치는 것으로 나타났다. 또한 가장 친환경적인 하수처리 및 슬러지 처리공법은 $A_2O$ 공법과 퇴비화로 환경에 가장 큰 영향을 미치는 CAS 공법과 매립에 비해 환경영향을 52% 줄일 수 있는 것으로 나타났다. 경제적인 측면에서는 가장 많은 비용을 소요하는 CAS 공법과 매립 적용 시에 비해 MUCT 공법과 퇴비화가 전생애비용을 62% 절약할 수 있음을 알 수 있었다. 본 연구를 통해 고도처리 공법으로의 증설 및 슬러지 처리에 대한 전과정을 고려하여 친환경적이며 경제적인 공법을 선정하기 위해 전과정평가를 수행하고 전생애비용을 산출하여 각 공법을 비교 및 평가하였으며, 전과정평가의 환경성 및 경제성에 중요한 영향인자를 분석하였다. 따라서 본 연구의 방법론을 통하여 환경부하 및 경비 절감을 고려한 고도처리공법의 개보수 공정 및 슬러지 공정 선택이 가능할 것으로 예상된다.

• Journal of Microbiology and Biotechnology
• /
• 제11권6호
• /
• pp.994-1001
• /
• 2001

An easier way of understanding the BNR system was proposed from the study on substrate, nutrient removal tendency, microbial community and its metabolic function by applying the municipal settled sewage. During the anaerobic period, the phosphorus release rate per VFACOD we varied depending on the phosphorus content in the sludge. When the phosphorus content in the sludge was $6\%$ VSS, according to influent VFACOD, the phosphorus release rate and PHA production were $0.35 gPO_4P/gVFACOD$ and 1.0 gPHA/gVFACOD, respectively. The $NO_3N$ requirement for the phosphorus uptake as an electron acceptor was about $0.5 gNO_3N/gPO_4P_{uptake}$ based on the proposed equation with PHA, biomass, production, and the concentration of phosphorus release/uptake. Bacterial-community analysis of the sludge, as determined by FISH and 16SrDNA characterization FISH, revealed that the beta-subclass proteobacteria were the most abundant group ($27.9\%$ of the proteobacteria-specific probe EUB338), and it was likely that representative of the beta-subclass played key roles in activated sludge. The next dominant group found was the gamma-protebacteria ($15.4\%$ of probe EUB338). 16S rDNA clone library analysis showed that the members of${\beta}$- and ${\gamma}$-proteobacteria were also the most abundant groups, and $21.5\%$ (PN2 and PN4) and $15.4\%$ (PN1 and PN5) of total clones were the genera of denitrifying bacteria and PAO, respectively. Prediction of the microbial community composition was made with phosphorus content (Pv, $\%$ P/VSS) in wasted sludge and profiles of COD, PHA, $PO_4P,\;and\;NO_3N$ in an anaerobic-anoxic SBR unit. Generally, the predicted microbial composition based upon metabolic function, i.e., as measured by stoichiometry, is fairly similar to that measure by the unculturable dependent method. In this study, a proposal was made on he microbial community composition that was more easily approached to analyze the reactor behavior.

• 대한환경공학회지
• /
• 제33권3호
• /
• pp.212-221
• /
• 2011

우리나라의 공공하수처리시설은 생물학적 인 제거공정을 운전하고 있으나, '12년부터 지역구분(I, II, III)에 따라 각각 0.2, 0.3 및 0.5 mg/L로 강화되는 방류수수질기준을 준수하기 위해서는 화학물질을 이용한 추가적인 인 처리시설을 적용할 필요성이 대두되었다. 강화된 총인의 수질기준을 만족하기 위해 적용된 물리화학적 처리기술 성능의 구체적인 운영자료 구축을 위하여, 화학적 응집제 사용 중인 인 처리시설 중 모범적으로 가동하고 있는 국내 시설의 운영 데이터를 분석하여 처리성능을 평가하였다. 또한, jar 테스트를 이용해 물리화학적 인 제거공정 적용 시 최적 응집제 주입율 도출, 인 제거 및 슬러지 발생특성을 관찰하고 약품비용과 슬러지 발생증가량을 산정하여 실처리장에 응집제 적용 시 예상되는 경제성 분석을 하였다. 활성슬러지를 이용한 jar 테스트 결과, 0.5와 0.2 mg/L 이하의 총인 농도를 달성하기 위해 필요한 최소한의 응집제(황산알루미늄, 폴리염화알루미늄)의 주입농도는 각각 25와 30 mg/L (as $Al_2O_3$)이며, 2차 처리수의 경우에는 동일한 총인 농도를 달성하기 위해 요구되는 응집제 주입농도가 활성슬러지에 비해 약 1/12~1/3 수준으로 감소하였다. jar 테스트 결과, 활성슬러지에 응집제를 주입할 경우에 고형물 농도가 약 10~11%가 증가할 것으로 예측되었다. 한편, 활성슬러지에 응집제를 주입하는 경우의 응집제(황산알루미늄) 구입비는 2차 처리수에 주입하는 경우에 비해 약 4~10배 정도가 증가할 것으로 산정되었다. 또한, 슬러지 발생량은 약 4~10배 정도 증가할 것으로 예측되었다.

• 대한환경공학회지
• /
• 제27권5호
• /
• pp.555-561
• /
• 2005

본 연구에서는 유기성폐기물의 최종생분해도를 평가하여 혐기소화조의 정확한 효율평가를 위한 기초자료를 확보하고 유기물의 분해경향을 보다 정확히 평가할 수 있는 다중 분해속도분석(Multiple k analysis)기법을 개발하여 다중 분해속도상수와 각각의 분해속도에 관여하고 있는 기질의 분율을 산정하려는데 목적이 있다. 연구 결과 폐활성슬러지의 최종생분해도는 50%, 농축슬러지는 40%로 평가되어 85%내외의 생분해도를 나타낸 Sorghum이나 Swine Waste에 비해 현저히 낮았다. 활성슬러지의 경우 생분해가능한 기질의 71%가 22일내에 초기분해속도상수 $k_1$인, $0.151\;day^{-1}$로 빠르게 분해되고 그 이후로 남아 있는 29%의 기질이 분해속도상수 $k_2$인, $0.021\;day^{-1}$로 아주 느리게 분해되었다. 반면 농축슬러지의 경우는 기질의 39%만이 $k_1$인, $0.123\;day^{-1}$로 빠르게 분해되었으며 60% 이상이 $k_2$인, $0.001\;day^{-1}$로 매우 느리게 분해되었다. 한편 Sorghum은 초기분해속도상수($k_1$)인 $0.248{\sim}0.358\;day^{-1}$ 범위로 기질의 약 90%($S_1$)가 16일 이내에 빠르게 분해되었으며 축분의 경우 $k_1$인, $0.155{\sim}0.209\;day^{-1}$ 범위로 기질의 $84{\sim}91%(S_1)$가 14일 이내에 빠르게 분해됨을 알 수 있다. 따라서 Multi k Analysis방법을 이용하여 도출된 하수 슬러지의 분해속도상수와 기질의 분율 및 분해패턴을 토대로 혐기성소화시 효율적이고 경제적인 HRT의 산정이 가능하다.