• Journal of Korean Society of Water and Wastewater
• /
• v.25 no.3
• /
• pp.307-312
• /
• 2011

The potential of algal-bacterial culture was investigated for advanced treatment of animal wastewater. Fed-batch experiments were carried out to examine treatability of nitrogen and phosphorus in different microbial consortium: Chlorella vulgaris, activated sludge, three microalgae strains (Scenedesmus, Microcystis, Chlorella) and Bacillus consortium, and three microalgae strains and sludge consortium. Single culture of C. vugaris showed the better efficiency for nitrogen removal but was not good at organic matter and phosphorus removal compared with activated sludge. Three microalgae and Bacillus consortium was best culture among the culture and consortium for pollutants removal tested in this experiment. Effect of $CO_2$ addition was studied by using three microalgae and Bacillus consortium. $CO_2$ addition enhanced T-P removal efficiency up to 60%. However, removal efficiencies of T-N and ammonia nitrogen reduced on the contrary.

• Journal of Microbiology and Biotechnology
• /
• v.17 no.11
• /
• pp.1772-1781
• /
• 2007

Activated sludge was sequentially adapted to benzene, toluene, and o-xylene (BTX) to study the effects on the change of microbial community. Sludge adapted to BTX separately degraded each by various rates in the following order; toluene>o-xylene>benzene. Degradation rates were increased after exposure to repeated spikes of substrates. Eleven different kinds of sludge were prepared by the combination of BTX sequential adaptations. Clustering analyses (Jaccard, Dice, Pearson, and cosine product coefficient and dimensional analysis of MDS and PCA for DGGE patterns) revealed that acclimated sludge had different features from nonacclimated sludge and could be grouped together according to their prior treatment. Benzene- and xylene-adapted sludge communities showed similar profiles. The sludge profile was affected from the point of the final adaptation substrate regardless of the adaptation sequence followed. In the sludge adapted to 50 ppm toluene, Nitrosomonas sp. and bacterium were dominant, but these bands were not dominant in benzene and benzene after toluene adaptations. Instead, Flexibacter sp. was dominant in these cultures. Dechloromonas sp. was dominant in the culture adapted to 50 ppm benzene. Thauera sp. was the main band in the sludge adapted to 50 ppm xylene, but became vaguer as the xylene concentration was increased. Rather, Flexibacter sp. dominated in the sludge adapted to 100 ppm xylene, although not in the culture adapted to 250 ppm xylene. Two bacterial species dominated in the sludge adapted to 250 ppm xylene, and they also existed in the sludge adapted to 250 ppm xylene after toluene and benzene.

• 한국생물공학회:학술대회논문집
• /
• 2001.11a
• /
• pp.590-593
• /
• 2001

The effect of salinity on the nitrification efficiency of the nitrifier consortium was evaluated for the nitrification of saline wastewater. The nitrifier consortium, which was the activated sludge acclimated with ammonium as the only energy source, was used as the nitrifier for the salt acclimation. Airlift reactors for the nitrification of ammonia with increasing concentration in saline synthetic wastewater (35 g/I NaCD, and synthetic wastewater without salt as a control, were continuously operated with the nitrifier consortium for 43 days. The ammonia removal rate was about 23g ammonia-N/$m^3$/day in both the absence and presence of the salt. An accumulation of nitrite was observed in the saline nitrification reactor at an early period. However, the nitrite decreased to less than 1 mg/l after 39 days of operation. The salinity increased the acclimation time of the nitrifier consortium to obtain a stable marine nitrification system. However, the salt acclimated system showed the efficient removal of ammonia which was same as that without salt.

• KSBB Journal
• /
• v.16 no.1
• /
• pp.61-65
• /
• 2001

In this study, a BTX degrading microbial consortium was obtained from the activated sludges of a BTX releasing sewage water and city sewage water treatment plant. The MY microbial consortium was developed for benzene and toluene degradation, whereas the MA microbial consortium was developed for xylene isomers. The major microorganism of the MA consortium was identified as Rhodococcus ruber DSM 43338T, whereas that of the MY consortium was Rhodococcus sp. In terms of the degradation of a single component, the removal rate of benzene was fastest and decreased in order; toluene, o-xylene, p-xylene and m-xylene. For degradation of mixed BTX, most BTX were degraded within 108 hours and the degradation rate showed either stimulatory or inhibitory effects depending on the composition. MA and MY microbial consortium obtained in this study may be used effectively to remove BTX biologically.

• Journal of Microbiology and Biotechnology
• /
• v.29 no.9
• /
• pp.1434-1443
• /
• 2019

Although chemical oxygen demand (COD) is an important issue for wastewater treatment, COD reduction with microalgae has been less studied compared to nitrogen or phosphorus removal. COD removal is not efficient in conventional wastewater treatment using microalgae, because the algae release organic compounds, thereby finally increasing the COD level. This study focused on enhancing COD removal and meeting the effluent standard for discharge by optimizing sludge inoculation timing, which was an important factor in forming a desirable algae/bacteria consortium for more efficient COD removal and higher biomass productivity. Activated sludge has been added to reduce COD in many studies, but its inoculation was done at the start of cultivation. However, when the sludge was added after 3 days of cultivation, at which point the COD concentration started to increase again, the algal growth and biomass productivity were higher than those of the initial sludge inoculation and control (without sludge). Algal and bacterial cell numbers measured by qPCR were also higher with sludge inoculation at 3 days later. In a semi-continuous cultivation system, a hydraulic retention time of 5 days with sludge inoculation resulted in the highest biomass productivity and N/P removal. This study achieved a further improved COD removal than the conventional microalgal wastewater treatment, by introducing bacteria in activated sludge at optimized timing.

• Journal of Microbiology and Biotechnology
• /
• v.10 no.3
• /
• pp.410-414
• /
• 2000

The effect of the COD/N ratio on denitrification characteristics was evaluated for the development of a denitrification process. Activated sludge, acclimated to an anoxic condition, was used as the denitrifier consortium (mixture of denitrifying organisms) for enhanced nitrogen removal in a recirculating aquarium system. Synthetic wastewater containing nitrate was used as the influent solution and glucose was used as the carbon source for denitrification. The COD/N ratio varied within a range of 1.5-7.2. The denitrification efficiency was higher than 97% even at a COD/N ratio of 1.5. Under a theoretical COD/N ratio of 3.0, nitrite was detected, however, the amount was less than 1% of the total influent nitrogen. The number of both nitrate-reducing bacteria and denitrifying bacteria reached $3.5{\times}10^5/ml$ with a COD/N ratio of 1.5 after 45 days of operation.

• Microbiology and Biotechnology Letters
• /
• v.47 no.4
• /
• pp.630-638
• /
• 2019

Nitrous oxide (N₂O) is a greenhouse gas with a global warming potential 310 times higher than that of carbon dioxide. In this study, an N₂O-reducing consortium was obtained by enrichment culture using advanced treatment sludge as the inoculum. The dominant bacteria in the consortium were Sulfurovum (17.95%), Geobacter (14.63%), Rectinema (11.45%), and Chlorobium (8.24%). The consortium displayed optimal N₂O reducing activity when acetate was supplied as the carbon source at a carbon/nitrogen ratio (mol·mol^-1) of 6.3. The N₂O reduction rate increased with increasing N₂O concentration at less than 3,000 ppm. Kinetic analysis revealed that the maximum N₂O reduction rate of the consortium was 163.9 ㎍-N·g-VSS^-1·h^-1. Genes present in the consortium included nosZ (reduction of nitrous oxide to N₂), narG (reduction of nitrate to nitrite), nirK (reduction of nitrite to nitric oxide), and norB (reduction of nitric oxide to nitrous oxide). These results indicate that the N₂O-reducing consortium is a promising bioresource that can be used in denitrification and N₂O mitigation.

• Microbiology and Biotechnology Letters
• /
• v.47 no.4
• /
• pp.585-595
• /
• 2019

Analysis of bacterial communities based on their 16S rDNA sequences revealed the predominance of Proteobacteria (Aeromonas sp., Acinetobacter sp. and Thaueraamino aromatica sp.) and uncultured bacterium in activated sludge from the effluent treatment plant (ETP) of Mother Dairy, Calcutta (India). Each isolate was used for bioremediation of dairy wastewater with simultaneous conversion of nitrogenous pollutants into ammonia. A consortium developed using seven of these isolates and three Bacillus strains from different environmental origins could reduce 93% nitrate with simultaneous production of ammonia (626 ㎍/100 ml) within 20 h in non-aerated, immobilized conditions as compared to 82% nitrate reduction producing 2.4 ㎍/100 ml ammonia in 96 h with extensive aeration in a conventional ETP. The treated ammonia-rich effluent could be used instead of freshwater and fertilizer during cultivation of mung bean with 1.6-fold increase in grain yield. The ETP with the surrounding agricultural land makes this process a zero liquid discharge technology for using the biofertilizer generated. In addition, the process requires minimal energy supporting sustained environmental health. This method is thus proposed as an alternative approach for small-scale dairy ETPs.

• Membrane and Water Treatment
• /
• v.10 no.3
• /
• pp.213-221
• /
• 2019

Anaerobic digestion (AD) has been widely used to valorize food waste (FW) because of its ability to convert organic carbon into $CH_4$ and $CO_2$. Korean FW has a high content of fruits and vegetables, and efficient hydrolysis of less biodegradable fibers is critical for its complete stabilization by AD. This study examined the digestates from different anaerobic digesters, namely Rs, Rr, and Rm, as the inocula for the AD of vegetable waste (VW) and cellulose (CL): Rs inoculated with anaerobic sludge from an AD plant, Rr inoculated with rumen fluid, and Rm inoculated with anaerobic sludge and augmented with rumen fluid. A total of six conditions ($3\;inocula{\times}2\;substrates$) were tested in serial subcultures. Biogas yield was higher in the runs inoculated with Rm than in the other runs for both VW (up to 1.10 L/g VS added) and CL (up to 1.05 L/g VS added), and so was biogas production rate. The inocula had different microbial community structures, and both substrate type and inoculum source had a significant effect on the formation and development of microbial community structures in the subcultures. The overall results suggest that the bioaugmentation with rumen microbial consortium has good potential to enhance the anaerobic biodegradability of VW, and thereby can help more efficiently digest high fiber-content Korean FW.

• Journal of Korean Society of Environmental Engineers
• /
• v.31 no.10
• /
• pp.919-926
• /
• 2009

Enrichment of anaerobic ammonium oxidation (ANAMMOX) bacteria is the essential step for operating full-scale ANAMMOX bioreactor because adding a significant amount of seeding sludge is required to stabilize the ANAMMOX reactor. In this study, the enrichment of ANAMMOX bacteria from an activated sludge using sequencing batch reactor was conducted and verified by analyzing changes in the microbial community structure. ANAMMOX bacteria were successfully enriched for 70 days and the substrate removal efficiencies showed 98.5% and 90.7% for $NH_4\;^+$ and $NO_2\;^-$ in the activity test, respectively. The phylogenetic trees of Planctomycetes phylum showed that the diverse microbial community structure of an activated sludge was remarkably simplified after the enrichment. All 36 clones, obtained after the enrichment, were affiliated with ANAMMOX bacteria of Candidatus Brocadia (36%) and Candidatus Anammoxoglobus (64%) genera. The quantification using real-time quantitative PCR (RTQ-PCR) revea ed that the 16S rDNA concentration of ANAMMOX bacteria was 74.8% compared to the granular ANAMMOX sludge obtained from an upflow ANAMMOX sludge bed reactor which had been operated for more than one year. The results of molecular analysis supported that the enriched sludge could be used as a seeding sludge for a full-scale ANAMMOX bioreactor.