• Journal of the Korea Organic Resources Recycling Association
• /
• v.16 no.4
• /
• pp.91-97
• /
• 2008

The objective of this research is to investigate the effect of the addition of granular activated carbon (GAC) and granular sludge on the performance of upflow anaerobic sludge blanket (UASB) reactors for treating leachate. For the control reactor, sludge obtained from an anaerobic digester was used as a seed material. On the other hand, GAC and granular sludge were incorporated with the seed sludge in the GAC reactor and the Granule reactor, respectively. The shortest acclimation period was observed in the Granule reactor. The GAC reactor also gave comparable performance to the Granule reactor at the beginning of operation. However, as the adsorptive capacity of GAC was exhausted, the effluent COD concentration increased gradually. Once the systems were stabilized, the GAC reactor showed slightly better results than the other two reactors in terms of chemical oxygen demand (COD) removal. COD removal in all reactors was more than 90% at hydraulic retention time of 1.0 day. Furthermore, GAC reactor showed little variation in COD removal rate and remained at 95% with organic loading rate (OLR) of 4.0 to $8.2kg\;COD/m^3.d$. Initial operating period was reduced by the addition of granular sludge, while the treatment efficiency was enhanced by the addition of GAC.

• 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 the Korea Organic Resources Recycling Association
• /
• v.14 no.4
• /
• pp.151-160
• /
• 2006

Anaerobic treatment of landfill leachate was studied to investigate the behaviors of pollutant and the characteristics of microorganism for 10 months. The upflow anaerobic sludge blanket (UASB) reactor achieved about 90% chemical oxygen demand (COD) removal at organic loading rates(OLR) up to $20kgCOD/m^3.d$. At higher OLR ($8-20kgCOD/m^3.d$), the propionate concentration increased, indicating that converting propionate to acetate was the rate-limiting step. Nevertheless, increase in the precipitate inside and on the surface of granules as well as on the wall of the reactor resulted in operational problems. The main inorganic precipitate in the granule was calcium compound. Although specific methanogenic activity (SMA) was not affected seriously in this study, metals had to be removed prior to anaerobic treatment so as to be free from the excessive inorganic accumulation that resulted in operational problems.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.15 no.2
• /
• pp.136-146
• /
• 2007

Landfill leachate was successfully treated in upflow anaerobic sludge blanket (UASB) reactors regardless of the addition of granular sludge. Initial operating period was significantly reduced by the addition of granular sludge. At hydraulic retention time (HRT) of one day, chemical oxygen demand (COD) removal rates in Control and Granule reactor were maintained over 90%, respectively with organic loading rate (OLR) of $4-8kgCOD/m^3.d$. During the experiment, the inorganic precipitates were accumulated in and around the sludge, and in the wall of the reactors were formed in both reactors regardless of addition of granular sludge. Specific methanogenic activity (SMA) increased as adaptation of microorganism to the substrate and OLR were increased. The maximum SMA value of the sludge for Granule reactor was about $0.57gCOD/g{\cdot}VSS{\cdot}.d$. The SMA value was not decreased because of excessive inorganic accumulation, however, it was needed to have pre-treatment process of influent to remove the inorganic metals.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.14 no.3
• /
• pp.126-137
• /
• 2006

Behaviors of simple organic compound and granular sludge in an upflow anaerobic sludge blanket (UASB) reactor treating propionate at high ammonia nitrogen levels were investigated for 12 months. The UASB reactor achieved about 80% removal of chemical oxygen demand (COD) at ammonia nitrogen concentration up to 6000 mg-N/L. At higher concentration of ammonia nitrogen, the propionate in the effluent increased whereas the acetate was very low. At ammonia nitrogen concentration of 8000 mg-N/L, the volatile suspended solids (VSS) increased sharply due probably to the decrease of the content of extracellular polymer (ECP) although methane production was very low. The specific methanogenic activity (SMA) using formate, acetate, and propionate as substrate to granules decreased as ammonia nitrogen concentration increased. The ammonia nitrogen concentration $I^{50}$, causing 50% inhibition of SMA were 2666, 4778 and 5572 mg-N/L, respectively. The kinetic coefficients of ammonia inhibition using formate, acetate, and propionate as substrate were 3.279, 0.999 and 0.609, respectively. The SMA using formate was severely affected by ammonia nitrogen than those using acetate and propionate. This result indicated that the hydrogenotrophic methanogens was most affected by ammonia nitrogen. Granules were mainly composed of microcolonies of methanothrix-like bacteria resembling bamboo-shape, and several other microcolonies including propionate degrader with juxtapositioned syntrophic associations between the hydrogen-producing acetogens and hydrogen-consuming methanogens.

• Journal of Korean Society on Water Environment
• /
• v.23 no.6
• /
• pp.993-997
• /
• 2007

The upflow anaerobic sludge blanket (UASB) reactor can be effective for treating simple organic compounds containing high concentration of ammonia nitrogen. The chemical oxygen demand (COD) removal efficiency was about 80% at ammonia nitrogen concentration up to 6,000 mg-N/L. This result also showed that it would be possible to treat propionate effectively at free ammonia nitrogen concentration up to 724 mg-N/L if sufficient time was allowed for adaptation. However the specific methanogenic activity (SMA) of granule was lower than that of granule in the reactor with lower ammonia nitrogen concentration. At 8,000 mg-N/L, the inhibition of high ammonia concentration was observed with evidence of increase of the volatile suspended solids (VSS) concentration in the effluent. It might be ascribed to the decrease in the content of extracellular polymer (ECP), which resulted to the sloughing off of obligated proton-reducing acetogens and heterogenotrophic methanogens from the exterior of granular sludge. This caused a great portion of the finely sludge to be easily washed out. Therefore, failure to maintain the balance between these two groups of microorganism cause accumulation of the hydrogen partial pressure in the reactor, which could have inhibited the growth of acetate utilizing methanogens.