• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.17 no.1
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• pp.41-47
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• 1981

The characteristics of septic tank sludges were investigated and the kinetic coefficients in the aerobic biodegradation were evaluated from bach treatability tests. Using an unbiased statistical method, the estimated values, k (substrate removal rate coefficient) =0. 0175hr-1 at 17\ulcornerC, K. (Michaelis Menten constant) = 248mg/ e, a (cell yield coefficient)=0.625, and Kd (cell decay coefficient:' =0. 00192hr-1 were obtained based on biodegradable COD(mg/ \ulcorner) and volatile suspended solids(mg/\ulcorner). The relationship between COD and BOD, COD (mg/\ulcorner) =2. 1 BOD(mg/\ulcorner) +250, also was established for the septic tank sludges. Dilution was inevitable for the grit removal because of the high viscosity of the sludges. An aerobic activated sludge process rather than anaerobic processes was recommended for the removal of soluble organics after the removal of grit and suspended solids. A multi-stage activated sludge process was adapted for this highly concentrated and not easily-degradable waste. It was estimated that a four-stage activated sludge process would require 40 hours retention time compared to 92 hours for a single-stage process, 52 hours for a double-stage process, and 46 hours for a three stage process in order to achieve an effluent quality of 84mg/ e COD( 40mg/ e BOD) with about 4, OOOmg/ \ulcorner MLSS from an influent quality of I, 500mg/ t COD(714mg/.e BOD), while multi-stages beyond four stage would not save the required retention time significantly.

• Journal of the Korea Organic Resources Recycling Association
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• v.16 no.1
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• pp.31-38
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• 2008

Animal carcasses have always been and continue to be a major burden in animal production. The main aim of this study is to evaluate the feasibility of thermophilic anaerobic digestion for animal carcasses. A batch test using ground meat and organ as the model substrate showed that animal carcasses arehighly biodegradable at thermophilic anaerobic condition. The volatile solids (VS) destruction and $CH_4$ yieldranged from 52.7 to 58.5% and from 220 to 243 mL/g VS, respectively, at initial substrate VS in the range of 1.5~7.7%. However, high ammonia concentration inhibited continuous operation at substrate VS above 2.5%. As ammonia is formed during the degradation of proteineous organic materials, the major constituent of animal carcasses, the only way to reduce the ammonia concentration would be dilution. Co-digestion with other waste stream without high nitrogen content is recommended as an economically feasible approach for thermophilic digestion of animal carcass.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.10
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• pp.583-589
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• 2015

This study was performed to evaluate the feasibility of anaerobic pretreatment for the leachate solubilized from thermal hydrolysis of sewage sludge cake. Overall process for the treatment of sludge cake consists of thermal hydrolysis, crystallization of magnesium, ammonium, and phosphate (MAP) for the leachate and anaerobic digestion of supernatant from MAP crystallization. The experimental evidence showed that the optimum ratio of Mg : P for the struvite crystallization of leachate solubilized from thermal hydrolysis of sludge cake was 1.5 to 1.0 as weight basis at the pH of 9.5. With this operational condition, the removal efficiencies of ammonia nitrogen and phosphorous achieved 50% and 97%, respectively. The mesophilic batch test showed that the ultimate biodegradability of the supernatant from MAP crystallization reached 63% at S/I ratio of 0.5. The readily biodegradable fraction of 90% ($S_1$) of the MAP supernatant BVS (Biodegradable Volatile Solids, $S_0$) degraded with $k_1$ of $0.207day^{-1}$ for the initial 17 days where as the rest slowly biodegradable fraction ($S_2$) of 10% of BVS degraded with $k_2$ of $0.02day^{-1}$ for the rest of the operational period. Semi-Continuously Fed and Mixed Reactor (SCFMR) was chosen as one of the best candidates to treat the MAP supernatant because of its total solids content over 6%. Maximum average biogas production rates reached 0.45 v/v-d and TVS removal efficiency of 37~41% was achieved at an hydraulic retention time (HRT) of 20 days and its corresponding organic loading rate (OLR) of 1.43 g VS/L-d.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.7
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• pp.387-395
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• 2015

Anaerobic mesophilic batch test of several organic wastes were carried out by a graphical statistic analysis (GSA) to evaluate their ultimate biodegradability and two distinctive decay rates ($k_1$ and $k_2$) with their corresponding degradable substrate fractions ($S_1$ and $S_2$). Each 3 L batch reactor was operated for more than 100 days at the substrate to inoculum ratio (S/I) of 0.5 as an initial total volatile solids (TVS) mass basis. Their Ultimate biodegradabilities were obtained respectively as follow; 69% swine waste, 45% dairy cow manure, 66% slaughterhouse waste, 79% food waste, 87% food waste leachate, 68% primary sludge and 39% waste activated sludge. The readily biodegradable fraction of 89% ($S_1$) of Swine Waste BVS ($S_o$) degraded with in the initial 31 days with $k_1$ of $0.116day^{-1}$, where as the rest 11% slowly biodegradable fraction ($S_2$) of BVS degraded for more than 100 days with the long term batch reaction rates ($k_2$) of $0.004day^{-1}$. For the Food Waste and Waste Activated Sludge, their readily biodegradable portions ($S_1$) appeared 89% and 80%, which degrades with $k_1$ of $0.195day^{-1}$ and $0.054day^{-1}$ for an initial 15 days and 28 days, respectively. Their corresponding long term batch reaction rates ($k_2$) were $0.003day^{-1}$ and $0.002day^{-1}$. Results from other organic wastes are addressed in this paper. The theoretical hydraulic retention times (HRTs) of anaerobic digesters treating organic wastes are easily determined by the analysis of multiple decay rate coefficients ($k_1$ and $k_2$) and their corresponding biodegradable substrate fractions ($S_1$ and $S_2$).

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.3
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• pp.227-234
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• 2016

The influence of mixing on biogas production and organic material removal performance of solid state anaerobic digestion of dairy manure and sawdust bedding mixtures was evaluated using 22 L volume lab-scale digesters. After 45 days of anaerobic digestion at $37^{\circ}C$, cumulative methane yield of unmixed test unit ($73.1N{\cdot}mL/g-VS$) was almost 1.3 times of that of mixed one ($56.3N{\cdot}mL/g-VS$). The biodegradable volatile solids removal rate of unmixed test unit was 67%, which was almost 28% greater than mixed one. Our results reveal that unmixed condition is better than mixed one in terms of biogas production and organic material reduction.

• Environmental Engineering Research
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• v.24 no.3
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• pp.449-455
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• 2019

To investigate the effect of seaweed (SW) addition on anaerobic co-digestion of food waste (FW) and sewage sludge (SS), batch experiments were conducted at various substrate concentrations (2.5, 5.0, 7.5, and 10.0 g volatile solids (VS)/L) and mixing ratios ((FW or SS):SW = 100:0, 75:25, 50:50, 25:75, and 0:100 on a VS basis). The effect of SW addition on FW digestion was negligible at low substrate concentration, while it was substantial at high substrate concentrations by balancing the rate of acidogenesis and methanogenesis. At 10 g VS/L, $CH_4$ production yield was increased from 103 to $350mL\;CH_4/g$ VS by SW addition (FW:SW = 75:25). On the other hand, SW addition to SS enhanced the digestion performance at all substrate concentrations, by providing easily biodegradable organics, which promoted the hydrolysis of SS. $k_{hyd}$ (hydrolysis constant) value was increased from 0.19 to $0.28d^{-1}$ by SW addition. The calculation showed that the synergistic $CH_4$ production increment by co-digesting with SW accounted for up to 24% and 20% of total amount of $CH_4$ production in digesting FW and SS, respectively.

• Journal of Korean Society on Water Environment
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• v.36 no.4
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• pp.322-331
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• 2020

By introducing chemically enhanced primary treatment (CEPT) in the first stage of sewage treatment, organic matter in sewage can be effectively recovered. Because CEPT sludge contains a high biodegradable organic matter in volatile solids (VS), it is feasible to convert the collected CEPT sludge into energy through anaerobic digestion. This study examined the properties and biochemical methane potential (BMP) of the CEPT sludge obtained from a sewage treatment plant located in an ocean area. The CEPT sludge contains a VS content of 37,597 mg/L, which is higher than that of excessive sludge (ES), i.e., 33,352 mg-VS/L. In the methane generation reaction, the lag period was as short as 1 to 2 days. The BMP for the CEPT sludge was 0.57 ㎥-CH₄/kg-VS_removed which is better than that of ES, i.e., 0.36 ㎥-CH₄/kg-VS_removed. Unfortunately, the CEPT sludge showed a high salinity as 0.56~0.75% probably due to the saline sewage. Due to the salinity, repeated BMP testing in a sequencing batch reactor showed significantly low methane production rates and BMPs. Also, the ES showed a strongly reduced BMP when the salinity was adjusted from 0.20 to 0.70% by NaCl. The ES mixture with higher CEPT content showed a better BMP, which is suitable for co-digestion. Besides, anaerobic digestion for 100% CEPT sludge can be a considerable option instead of co-digestion.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.5
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• pp.959-970
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• 2000

A laboratory-scale experiment was conducted to investigate the effect of soluble microbial products(SMP) on permeate flux in the submerged membrane separation activated sludge process. Continuous and batch filtration test were operated to understand mechanism of relationship between membrane fouling and SMP. Synthetic wastewater(phenol) was used as a carbon source. Hydraulic retention time(HRT) and mixed-liquor volatile suspended solids(MLVSS) of the reactor were kept at 12 hours and 9.000mg VSS/L, respectively. Batch filtration tests ($J_{60}/J_o$) using the mixed liquor from reactor showed that the increase of accumulated SMP concentration in the reactor caused to the decreasing permeate flux and the increasing of the adhesion matters which form cake and gel layer. The resistance value of cake layer was measured $2.9{\times}10^{10}{\sim}4.0{\times}10^{10}(1/m)$, this value showed more significant effect on flux drop than that of among other resistance layers. Batch phenol-degradation experiment was conducted to observe SMP type expected $SMP_{nd}$ and $SMP_{e}$ (SMP resulted from endogenous cell decomposition), these are non-biodegradable high molecular weight organic matter and playa significant role in permeate flux drop. Also, SMP concentration was accumulated as increased of HRT against flux drop.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.8
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• pp.938-943
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• 2007

Anaerobic degradation of petroleum hydrocarbons in a soil artificially contaminated with 10,000 mg/kg soil of diesel fuel was tested by adding an anaerobic sludge taken from a sludge digestion tank. Treatments of soil(50 g) with 15 mL/kg soil and 30 mL/kg soil of the digestion sludge(2,000 mg/L of vss(volatile suspended solids)) showed 37.2% and 58.0% of total petroleum hydrocarbons(TPH) removal during 90 days incubation, respectively. In evaluation of several anaerobic conditions including nitrate reducing, sulfate reducing, methanogenic, and mixed electron accepters condition, treatments with the digested sludge showed significant degradation of diesel fuel under all anaerobic conditions compare to a control treatment of soil without the sludge and a treatment of autoclaved soil treatment with autoclaved digestion sludge. The rate of diesel fuel degradation was the highest in the treatment with the sludge and mixed electron accepters (75% removal of TPH) for 120 days incubation followed in order by sulfate reducing, nitrate reducing, methanogenic condition as 67%, 53%, 43%, respectively. However, the removal rate of non-biodegradable isoprenoid was the highest in the sulfate reducing condition. These results suggest that anaerobic degradation of diesel fuel in soil with digested sludge is effective for practical remediation of soil contaminated with petroleum hydrocarbons.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.8
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• pp.561-569
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• 2014

This study was carried out to get the characteristics of anaerobic digestion for chemical/biological sludge produced from municipal sewage treatment plant for phosphorus. Anaerobic mesophilic batch tests showed that the ultimate biodegradability of waste activated sludge showed 31%, PACl sludge 24%, Alum sludge 26%, respectively. At the S/I 1.0, 75% of total biodegradable volatile solids (TBVS) of waste activated sludge was degraded with an initial rapid decay coefficient, k1 of $0.1129day^{-1}$ and 74% of TBVS of PACl sludge with k1 of $0.0998day^{-1}$, and 76% of TBVS of Alum sludge with k1 of $0.1091day^{-1}$ for 20 days. During the operation of SCFMRs, the 3 reactor (Control, PACl, Alum) pH maintained 6.7~7.0 and the reactor alkalinity maintained 1,800~ 2,200 mg/L as $CaCO_3$. The average biogas production rates of SCFMRs fed with PACl sludge and Alum sludge were 0.089 v/v-d and 0.091 v/v-d, respectively, which was 27~28% lower than that of the control (0.124 v/v-d) at an HRT (hydraulic retention times) of 20 days. And the methane content during the operation ranged 70~76% in 3 reactor. The average TVS removal efficiency of SCFMRs fed with PACl sludge and Alum sludge were 19.6% and 19.9%, respectively, at an HRT of 20 days, which showed 4% lower than that of the control (23.8%). The average BVS removal efficiency of SCFMRs fed with PACl sludge and Alum sludge were 25.8% and 26.9%, respectively, at an HRT of 20 days, which was 8~9% lower than that of the control (34.5%).