• Journal of the Korea Organic Resources Recycling Association
• /
• v.16 no.3
• /
• pp.75-82
• /
• 2008

Two UASB reactors were operated to investigate the effect of high concentration of sulfate on anaerobic digestion of propionate using an upflow anaerobic sludge blanket (UASB) reactor. An organic loading rate of $1.2kg\;COD/m^3{\cdot}d$ and a hydraulic retention time of 1.6 d were maintained during this study. In the absence of sulfate, the UASB reactor achieved about 95% removal of chemical oxygen demand whereas in the presence of $2,000\;SO_4^{2-}mg/L$, the COD removal rate decreased to 83% due probably to the inhibition of dissolved sulfide inhibition. Interactions between the methane producing bacteria (MPB) and sulfate reducing bacteria (SRB) were measured to investigate the competition between MPB and SRB. The MPB consumed average 58% of the available electron donors at $COD/SO_4^{2-}$ ratio of 1. Propionate was consumed mainly by SRB, converting sulfate into sulfide and suppressing the methane production. The specific methanogenic activity (SMA) using acetate and propionate increased as microorganism acclimated to the substrate.

• Journal of Korean Society of Water and Wastewater
• /
• v.20 no.2
• /
• pp.273-280
• /
• 2006

The sludge settleability is a key factor for operating activated sludge process as well as BNR (biological nutrient removal) process, because the poor sludge settling causes an increase of suspended solid in the effluent. In order to improving the sludge settleability, a settling agent such as iron dust can be applied. In this study, the effect of sludge settleability on the performance of DNR (Daewoo nutrient removal) process was investigated with GPS-X, which is the popular wastewater treatment process model program, and the result of modeling was verified with operating lab-scale DNR process. As a result, if the sludge blanket keeps stable in the secondary settling tank, the effluent quality is similar in spite of different SVI values. And in case of the good sludge settleability, short HRT or long SRT increased the biomass concentration in the bioreactor, and improved the pollutant removal efficiency. In spite of daily influent changing, the good sludge settleability also guaranteed the stable effluent quality. And the results of the lab-scale DNR process experiment could support the simulated results.

• Journal of environmental and Sanitary engineering
• /
• v.13 no.2
• /
• pp.47-56
• /
• 1998

Effects of sulfate on the anaerobic substrate utilization were evaluated using UASB (Upflow Anaerobic Sludge Blanket) reactor. Effect of sulfate on the organic removal rate was dependent on the relative amount of microorganisms in the reactor, the operational condition, and the characteristics of sludge. When the sulfate shock was applied to 0.0 - 3.0g SO$_{4}$$^{2-}$/d, more than 95% of COD removal efficiency was achieved. Therefore, if F/M ratio was kept to low sufficiently with recirculation, it is shown that operation of the reactor was not affected significantly, though sulfate shock load was doubled compared to the normal operation. Provided that it is shocked by high strength of sulfate or temporary shock load is applied frequently the efficiency of reactor may be disadvantageous as well as the wash-out of sludge will be increased by decreasing the size to the accumulated frequency of granular sludge and the size with maximum frequency.

• Environmental engineer
• /
• v.21 s.210
• /
• pp.68-71
• /
• 2004

[ $\circ$ ] 본 기술은 기존의 A2O공법과 Sludge Blanket Filtration(SBF)을 단위공법으로 조합한 공정으로서 각 생물반응조의 미생물 농도를 6,000mg/ 이상의 고농도로 운전하여 생물학적 유기물,질소 및 인 제거효율을 극대화하고자 하는 기술 $\circ$ 또한 활성슬러지 반응조로부터 유입된 슬러지를 SBF에서 미세기포를 이용하여 부상시킴으로써 수면에 농축 슬러지층을 형성시키고 이 부

• Environmental Engineering Research
• /
• v.20 no.4
• /
• pp.363-369
• /
• 2015

This study aims to characterize solid household waste and to present physicochemical characteristics of fresh leachate before landfilling in Kasba Tadla city, Morocco. Obtained results show that household waste produced in 2013 were about 11,787 tons, or 0.27 tons/capita/year. These wastes were composed essentially of organic materials (74%), paper (8%), plastics (9%), metals (1%), and glass (0.5%). However, monthly produced leachate ranges from a maximum of $130.92m^3$ during summer and a minimum of $21.88m^3$ in winter. Moreover, leachate treatment using Upflow Anaerobic Sludge Blanket technique was accompanied by a decrease in electrical conductivity, certainly related to leachate-sediment chemical exchanges. Otherwise, the same acidity reduction phenomenon occurs when pH value increased from 4.49 to 6.17 after 24 hours, confirming the system response since the early stages of treatment. In addition, temporal evolution of the treatment efficiency in terms of COD highlighted a very important reduction which reached 94% after 5 days with an average temperature of $25^{\circ}C$.

• Journal of Korean Society of Environmental Engineers
• /
• v.28 no.4
• /
• pp.376-383
• /
• 2006

This study was undertaken to control sludge bulking and foaming problems at the biological nutrient removal processes. A sewage treatment plant(STP) had a severe sludge settling problem usually over 90% in 30 min settled sludge volume and 300 mL/g in SVI and also thick and heavy brown foam in the secondary clarifiers. Identification study shows that causative filament was Microthrix parvicella which has not been previously reported in Korea. According to the inspection of processes and other related parameters, excessive growth of this particular filament was associated with high SRT caused by lack of proper capacity in sludge treatment line. After providing an extension of the sludge treatment capability, the plant can decrease SRT by wasting more sludge from the processes and also decreasing SS concentration in recycled stream. Subsequently we were able to control growth of M. parvicella. The SVI value was reduced to half of those observed during the severe bulking, but also sludge blanket and its concentration in the clarifier became compact and dense. However, decrease in population of M. parvicella caused increase of total phosphorus concentration in the effluent.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2001.04a
• /
• pp.172-181
• /
• 2001

Upflow anaerobic sludge blanket (UASB) system employs granular sludge to treat various wastewaters including landfill leachate. CH$_4$ production of the granules determines overall performance of a UASB reactor. Sludge granules are developed by self-granulation of microorganisms and dynamic balance between granule growth and decay results in coexistence of granules with different sizes in the reactor. In this study, granules taken from a laboratory-scale UASB reactor were classified into 4 groups based on their diameters and their Physicochemical characteristics we were investigated. Each group was analyzed for settling ability, specific methanogenic activity (SMA), and elemental content. Settling ability was proportional to granule diameter. suggesting effective detainment of larger granules in the reactor. When acetate or glucose was used as a substrate, all groups showed relatively slight difference in SMA. However SMA with a volatile fatty acid mixture showed significant increase with granule diameter, suggesting better establishment of syntrophic relationship in larger granules. Larger granules showed higher value of SMA upon environmental changes (i.e., PH, temperature, or toxicant concentration). Comparative analysis of elemental contents showed that content (dry weight %) of most tested elements (iron, calcium, phosphorus, zinc, nickel. and manganese) deceased with granule diameter, suggesting importance of these elements for initial granulation. Taken together, this study verified experimentally that Physicochemical Properties of granules are related to granule size distributions. Overall results of physicochemical characterization supports that larger.

• Biotechnology and Bioprocess Engineering:BBE
• /
• v.8 no.1
• /
• pp.54-57
• /
• 2003

H$_2$-producing bacteria were isolated from anaerobic granular sludge. Out of 72 colonies (36 grown under aerobic conditions and 36 under anaerobic conditions) arbitrarily chosen from the agar plate cultures of a Suspended sludge, 34 colonies (15 under aerobic conditions and 19 under anaerobic conditions) produced H2 under anaerobic conditions. Based on various biochemical tests and microscopic observations, they were classified into 13 groups and tentatively identified as follows: From aerobic isolates, Aeromonar spp. (7 strains), Pseudomonas spp. (3 strains), and Vibrio spp. (5 strains); from anaerobic isolates, Actinomyces spp. (11 Strains), Clostridium 5pp. (7 strains). and Porphyromonas sp. When glucose was used as the carbon substrate, all isolates showed a similar cell density and a H$_2$ production yield in the batch cultivations after 12 h (2.24-2.74 OD at 600 nm and 1.02-1.22 mol H$_2$/mol glucose, respectively). The major fermentation by-products were ethanol and acetate for the aerobic isolates, and ethanol, acetate and propionate for the anaerobic isolates. This study demonstrated that several H$_2$ producers in an anaerobic granular sludge exist En large proportions and their performance in terms of H$_2$ production is quite similar.

• 한국생물공학회:학술대회논문집
• /
• 2000.11a
• /
• pp.508-511
• /
• 2000

In situ hybridization with fluorescent oligonucleotides(FISH) was used to detect and localize microorganisms in the granules of lab-scale upflow anaerobic sludge blanket(UASB) reactors. An UASB reactor was seeded with mesophilically-grown($35^{\circ}\;C$) granular sludge, and thermophilically($55^{\circ}\;C$) operated by feeding with a synthetic wastewater. Sections of the granules were hybridized with 16S rRNA-targeted oligonucleotide probes for Eubacteria, Archaeabacteria, and specific phylogenetic groups of methanogens. FISH clearly showed the layed structure of thermophilic granules, which was consisted of outer bacterial cells and inner archaeal cells. Methanoseata-, Methanosarcina-like cells were also found to be localized inside the granules. These results demonstrated FISH was useful in studying the spatial organizations of methanogens and in situ morphologies and metabolic functions in thermophilic granular sludges.

• Journal of Korean Society on Water Environment
• /
• v.25 no.6
• /
• pp.964-971
• /
• 2009

In this paper, activated sludge settling was characterized based on field trip and zone settling tests. Plants used for this study include 5 conventional activated sludge processes and 3 A2O type treatment processes. The treatment capacities are in the range from 12,000 to $250,000m^3$/day. Total number of zone settling tests were 188 set and SVI values representing settling characteristics were from 100 to 300 mL/g. It was found out that zone settling velocity of these examined plant sludges can be approximated by mean values calculated by Keinath and Daigger/Roper models. Based on these three models, solid flux analysis were carried out in order to compare design criteria ($3.96{\sim}6.04kg/m^2-hr$) recommended by Korea Sewage Facility Design Guideline with two models used in USA. The results show that design criteria are only applicable for normal condition in settling characteristics (below SVI 100 mL/g). Solid flux analysis of surveyed plants indicates that most of the plants are operated underload conditions except several plants experiencing poor sludge settling problem. Most of the plants are operated under high sludge blanket depths (SBD).