Sludge reduction performance and bacterial community dynamics in a pilot-scale multi-stage digester system with prolonged sludge retention time were characterized. Throughout the operation period of 281 days, the total loading sludge and the total digested sludge were 4700 and 3300 kg-MLSS. After 114 days of operation, the residual MLSS (RMLSS) in the reactors for sludge treatment was maintained at 18–25 kg-RMLSS m−3, and the sludge reduction efficiency achieved 95% under the F/M ratio (kg-loading MLSS kg-RMLSS−1) of less than 0.018. Also, among the sludge components, both fixed suspended solids and volatile suspended solids were reduced. Based on the sludge reduction performance and the RNA-based bacterial community characteristics, the combined action of the maintenance metabolism, lysis–cryptic growth, and particulate inorganic matter is proposed as the sludge reduction mechanism in the multi-stage sludge treatment process.

A pilot-scale biocover was installed at a sanitary landfill for municipal waste, and the removal of volatile organic compounds (VOCs) by the biocover was evaluated for a long period of 550 days. The biocover (2.5 m W × 5 m L × 1 m H) was constructed with the mixture of soil, perlite, earthworm cast and compost (6:2:1:1, v/v). The total VOCs concentration of the inlet gas into the biocover was 820.3 ppb~7,217.9 ppb, and the total VOCs concentration of the outlet gas from the surface of the biocover was 12.6 ppb~1,270.1 ppb. The average removal efficiency of total VOCs was 87.6 ± 11.0% (60.5% for minimum and 98.5% for maximum). Toluene concentration was the highest among the inlet VOCs, followed by ethylbenzene, m, p-xylene and o-xylene. These aromatic VOCs accounted for more than 50% of the total VOCs concentration. Other than these aromatic VOCs, hexane, cyclohexane, heptane, benzene, and acetone were major VOCs among the inlet VOCs. Compared with the VOC profiles in the inlet gas, the relative contribution of dichloromethane to the outlet VOCs emitted from the biocover layer increased from 0.1% to 15.3%. The average removal efficiencies of BTEX in the biocover were over 84% during the operation period of 550 days. The average removal efficiencies of hexane, cyclohexane and heptane in the biocover were 86.0 ± 18.9%, 85.4 ± 20.4% and 97.1 ± 4.0%, respectively. The removal efficiency of VOCs in the biocover decreased not only when the ambient temperature had fallen below 5oC, but also when the ambient temperature had risen above 23oC. Information on the VOCs removal characteristics of the biocover installed in the landfill field can be useful for commercializing the biocover technology for the treatment of VOCs.

Soil burial and composting methods have been widely used for the disposal of pig carcasses. The relationship between bacterial community structure and odor emission was examined using extended local similarity analysis (eLSA) during the degradation of pig carcasses in soil and compost. In soil, Hyphomicrobium, Niastella, Rhodanobacter, Polaromonas, Dokdonella and Mesorhizobium were associated with the emission of sulfur-containing odors such as hydrogen sulfide, methyl mercaptan and dimethyl disulfide. Sphingomonas, Rhodanobacter, Mesorhizobium, Dokdonella, Leucobacter and Truepera were associated with the emission of nitrogen-containing odors including ammonia and trimetylamine. In compost, however, Carnobacteriaceae, Lachnospiaceae and Clostridiales were highly correlated with the emission of sulfur-containing odors, while Rumincoccaceae was associated with the emission of nitrogen-containing odors. The emission of organic acids was closely related to Massilia, Sphaerobacter and Bradyrhizobiaceae in soil, but to Actinobacteria, Sporacetigenium, Micromonosporaceae and Solirubrobacteriales in compost. This study suggests that network analysis using eLSA is a useful strategy for exploring the mechanisms of odor emission during biodegradation of pig carcasses.

The performance of a biocomplex textile prototype was evaluated as an alternative daily cover at an operational landfill site to mitigate odors and methane. The biocomplex textile prototype consisted of two layers of nonwoven fabric and biocarrier immobilized microorganisms and showed excellent removal of odors and methane compared to landfill cover soil. The complex odor intensity (odor dilution ratio (ODR)) on the surface of landfill cover soil was 1,000-10,000 ODR (average of 4,204 ODR), whereas it was 5-250 ODR (average of 55 ODR) on the surface of biocomplex textile. Hydrogen sulfide, which contributes a significant odor intensity, had an average concentration on the biocomplex textile of 8.64 parts-per-billion (ppb), compared to 1733.21 ppb on the landfill cover soil. The biocomplex textile also showed effective methane removal with methane concentrations of 0-1.2% (average of 0.3%) on the biocomplex textile compared to 0-20% (average of 5.3%) on the landfill cover soil. Bacterial community diversity in the biocomplex textile increased with time until an operating period of 66 days, after which diversity indices were maintained at a constant level. The dominant species were the methanotrophs Methylocaldum and Methylobacter, and the non-methanotrophs Acinetobacter, Serpens, Ohtaekwangia, and Actinophytocola. These results demonstrate that on-site biocomplex textile is a suitable alternative daily cover to mitigate odors and methane in landfills.

Unpleasant odors emitted from landfills have been caused environmental and societal problems. For odor abatement, two pilot-scale biocovers were installed at a sanitary landfill site in South Korea. Biocovers PBC1 and PBC2 comprised a soil mixture with different ratios of earthworm casts as an inoculum source and were operated for 240 days. Their odor removal efficiencies were evaluated, and their bacterial community structures were characterized using pyrosequencing. In addition, the correlation between odor removability and bacterial community dynamics was assessed using network analysis. The removal efficiency of complex odor intensity in the two biocovers ranged from 81.1% to 97.8%. Removal efficiencies of sulfur-containing odors (hydrogen sulfide, methanethiol, dimethyl sulfide, and dimethyl disulfide), which contributed most to complex odor intensity, were greater than 91% in both biocovers. Despite the fluctuations in ambient temperature (-8.2 to 31.3 °C) and inlet complex odor intensity (10,000-42,748 of odor dilution ratio), biocovers PBC1 and PBC2 displayed stable deodorizing performance. A high ratio of earthworm casts as an inoculum source led to high odor removability during the first 25 days of operation, but different mixing ratios of earthworm casts did not significantly affect overall odor removability. A bacterial community analysis showed that Methylobacter, Arthrobacter, Acinetobacter, Rhodanobacter, and Pedobacter were the dominant genera in both biocovers. Network analysis results indicated that Steroidobacter, Cystobacter, Methylosarcina, Solirubrobacter, and Pseudoxanthomonas increased in relative abundance with time and were major contributors to odor removal, although these bacteria had a relatively low abundance compared to the overall bacterial community. These data contribute to a more comprehensive understanding of the relationship between bacterial community dynamics and deodorizing performance in biocovers.

A soil burial-composting method was proposed as a hybrid disposal method for infected carcasses. This is a modified soil burial technique that involves covering carcasses with compost to achieve a final compost bed of 1.0-1.2 m during the soil burial process. To evaluate the feasibility and applicability of the soil burial-composting method, a pilot-scale system was constructed to dispose of pig carcasses and monitored its performance for 346 days. Temperature around the pig carcasses in the compost bed increased gradually, and was in the range of 35-45 degrees C after 200 days. Mesophilic (Sporosarcina and Steroidobacter) and thermophilic (Truepera) bacteria were dominant in the compost bed. Based on odor gas profiling and the morphological properties of the carcasses excavated after 346 days, it was estimated that an advanced decay stage was reached after 243 days. Considering the results of previous studies, the carcass degradation rate achieved by soil burial-composting was faster than that of soil burial, but slower than that of the composting method. Sum of odor quotient (SOQ) in the upper soil bed was lower than the SOQ in the compost bed where the carcasses were buried. This result demonstrated that the upper soil bed functioned as a biofilter to mitigate odor gases emitted during degradation of the carcasses. The soil burial-composting disposal method is preferred over soil burial because the degradation of carcasses is faster, and over composting because odor complaints and compost usage can be minimized. (C) 2018 Elsevier Ltd. All rights reserved.

Soil burial is the most widely used disposal method for infected pig carcasses, but composting has gained attention as an alternative disposal method because pig carcasses can be decomposed rapidly and safely by composting. To understand the pig carcass decomposition process in soil burial and by composting, pilot-scale test systems that simulated soil burial and composting were designed and constructed in the field. The envelope material samples were collected using special sampling devices without disturbance, and bacterial community dynamics were analyzed by high-throughput pyrosequencing for 340 days. Based on the odor gas intensity profiles, it was estimated that the active and advanced decay stages were reached earlier by composting than by soil burial. The dominant bacterial communities in the soil were aerobic and/or facultatively anaerobic gram-negative bacteria such as Pseudomonas, Gelidibacter, Mucilaginibacter, and Brevundimonas. However, the dominant bacteria in the composting system were anaerobic, thermophilic, endospore-forming, and/or halophilic gram-positive bacteria such as Pelotomaculum, Lentibacillus, Clostridium, and Caldicoprobacter. Different dominant bacteria played important roles in the decomposition of pig carcasses in the soil and compost. This study provides useful comparative date for the degradation of pig carcasses in the soil burial and composting systems.

Space-saving biocomplex textiles, which can be used as covers or rolled up as needed, have been demonstrated as alternative daily covers for the simultaneous mitigation of greenhouse gases (GHGs) and odors in landfills. The biocomplex textiles were made by inserting inorganic biocarriers (perlite (P), tobermolite (T) and their mixture (P/T)) between nonwoven fabrics. Methane (CH4) and dimethyl sulfide (DMS) were used as model compounds for GHGs and odors, and a CH4 and DMS co-degrading microbial consortium was used as an inoculum source. CH4 and DMS could be biologically degraded by methanotrophs and sulfur-oxidizing bacteria in the biocomplex textiles. Both biocomplex textiles made with either P or T were able to maintain the removability for CH4 and DMS after storage for 70 days, although their removal efficiencies for CH4 and DMS were 70-71% and 62-65% of those before storage, respectively. CH4 and DMS were simultaneously removed in lab-scale landfill simulation reactors employed with the biocomplex textiles. After 17 days of starvation, only 2-3 days were needed to recover their removability. Among the 3 kinds of biocarriers evaluated, the biocomplex textile generated using the P/T showed the highest removability and was the most stable. The maximum elimination capacities of the biocomplex textile generated with the P/T were 11.5 g-CH4·m-2-fabric·d-1 and 0.5 g-DMS·m-2-fabric·d-1, respectively. These results suggest that the biocomplex textiles are promising alternative daily covers to mitigate the emission of greenhouse gas and odor in operational landfills.

The mycoremediation has been considered as a promising method for decolorizing dye wastewater. To explore new bioresource for mycoremediation, a new white-rot fungus that could decolorize various dyes commonly used in textile industries was isolated, and its ligninolytic enzyme activity and decolorization capacity were characterized. The isolated CBR43 was identified as Trametes versicolor based on the morphological properties of its fruit body and spores, as well as through partial 18S rDNA gene sequences. Isolated CBR43 displayed high activities of laccase and Mn-dependent peroxidase, whereas its lignin peroxidase activity was relatively low. These ligninolytic enzyme activities in potato dextrose broth (PDB) medium were enhanced by the addition of yeast extract (1-10g L-1). In particular, lignin peroxidase activity was increased more than 5times in the PDB medium amended with 10g L-1 of yeast extract. The CBR43 decolorized more than 90% of 200mg L-1 acid dyes (red 114, blue 62 and black 172) and reactive dyes (red 120, blue 4, orange 16 and black 5) within 6days in the PDB medium. CBR43 decolorized 67% of 200mg L-1 acid orange 7 within 9days. The decolorization efficiencies for disperse dyes (red 1, orange 3 and black 1) were 51-80% within 9days. The CBR43 could effectively decolorize high concentrations of acid blue 62 and acid black 172 (500-700mg L-1). The maximum dye decolorization rate was obtained at 28 degrees C, pH 5, and 150rpm in the PDB medium. T. versicolor CBR43 had high laccase and Mn-dependent peroxidase activities, and could decolorize a wide variety of dyes such as acid, disperse and reactive textile dyes. This fungus had decolorizing activities of azo-type dyes as well as anthraquinone-type dyes. T. versicolor CBR43 is one of promising bioresources for the decolorization of textile wastewater including various dyes.

Contaminated livestock disposal method includes burial method using soil. But the slow rate of decay process of carcasses has caused various problems. In this study, 4 pig carcasses (80 similar to 90 kg/pig) were buried in livestock compost as a cover material to improve carcasses decaying rate. The result of experiment showed the temperature of the carcass layer remained 40 degrees C or higher even when the outside temperature dropped below zero. After the experiment, it was confirmed that carcasses in the compost burial was decomposed substantially than the carcasses from soil burial. The moisture content of the compost burial was 40 similar to 65%. The pH was affected by ammonia produced by decaying carcasses and the pH level was increased from pH 8.7 similar to 8.9 at the beginning of the experiment to 9.3 similar to 9.7 at the end of the experiment. The residues of typical odor components in the compost layer were decreased after volatilized and due to decaying carcasses strong odor was observed. The odor intensity evaluation by measured odor substances and olfactory evaluation showed overall favorable correlation, and among the measured odor substances the reduced sulfur compounds (RSC) were found to be dominantly contributing to malodorous substances of decaying carcasses. The above results proved rapid decay rates due to the thermal effects of livestock compost.

The mycoremediation has been considered as a promising method for decolorizing dye wastewater. To explore new bioresource for mycoremediation, a new white-rot fungus that could decolorize various dyes commonly used in textile industries was isolated, and its ligninolytic enzyme activity and decolorization capacity were characterized. The isolated CBR43 was identified as Trametes versicolor based on the morphological properties of its fruit body and spores, as well as through partial 18S rDNA gene sequences. Isolated CBR43 displayed high activities of laccase and Mn-dependent peroxidase, whereas its lignin peroxidase activity was relatively low. These ligninolytic enzyme activities in potato dextrose broth (PDB) medium were enhanced by the addition of yeast extract (1–10 g L−1). In particular, lignin peroxidase activity was increased more than 5 times in the PDB medium amended with 10 g L−1 of yeast extract. The CBR43 decolorized more than 90% of 200 mg L−1 acid dyes (red 114, blue 62 and black 172) and reactive dyes (red 120, blue 4, orange 16 and black 5) within 6 days in the PDB medium. CBR43 decolorized 67% of 200 mg L−1 acid orange 7 within 9 days. The decolorization efficiencies for disperse dyes (red 1, orange 3 and black 1) were 51–80% within 9 days. The CBR43 could effectively decolorize high concentrations of acid blue 62 and acid black 172 (500–700 mg L−1). The maximum dye decolorization rate was obtained at 28°C, pH 5, and 150 rpm in the PDB medium. T. versicolor CBR43 had high laccase and Mn-dependent peroxidase activities, and could decolorize a wide variety of dyes such as acid, disperse and reactive textile dyes. This fungus had decolorizing activities of azo-type dyes as well as anthraquinone-type dyes. T. versicolor CBR43 is one of promising bioresources for the decolorization of textile wastewater including various dyes.