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Volume 42 (2006)
- Issue 4 Pages 159-
- Issue 3 Pages 99-
- Issue 2 Pages 45-
- Issue 1 Pages 1-
Volume 42, Issue 3
Displaying 1-6 of 6 articles from this issue
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ORIGINALS
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CHIKA TADA, SHIGERU HAYASHIBARA, YOUICHI UTATSU, SHIGEKI SAWAYAMAArticle type: ORIGINALS
2006 Volume 42 Issue 3 Pages 99-106
Published: 2006
Released on J-STAGE: March 10, 2018
JOURNAL FREE ACCESSIn this study, the effects of Fe-type, Ca-type, and low-sodium-level Ca-type artificial zeolites, made from waste coal ash, on methane production and the methanogen communities under ammonium-rich conditions were investigated. Methane production with Fe-type zeolite was higher than that with the other types of zeolites, and was about four times higher than that without zeolite. Acetate was not accumulated during anaerobic digestion of ammonium-rich organic waste with Fe-type zeolite. The methanogen community which were analysed by real-time polymerase chain reaction (PCR) with Fe-type zeolite was almost the same as that with Ca-type zeolite. These results showed that quantities of methanogen have not relation with the volume of methane production. A comparison of methane production with Fe-type zeolite and that with Fe ions or Ca ions in anaerobic digestion under ammonium-rich conditions confirmed that Fe-type zeolite was the most effective in enhancing methane production, Ca ions addition was not enhancing the methane production contrary. Fe-type zeolite is considered to play two roles in anaerobic digestion; namely, supplying iron to the anaerobic microbes, and decreasing the ammonium concentration.View full abstractDownload PDF (710K) -
TAKAYUKI NISHIO, TARO YOSHIKURA, YASUHIRO FUJIWARA, ISAO FUKUNAGAArticle type: ORIGINALS
2006 Volume 42 Issue 3 Pages 107-117
Published: 2006
Released on J-STAGE: March 10, 2018
JOURNAL FREE ACCESSAt a sea-based solid waste disposal site where intermittent landfill is employed to control the concentration of nitrogenous and organic pollutants, nitrification and denitrification activity in the sediment and water of a facultative pretreatment pond were investigated in order to estimate the contribution of these two processes to maintaining the water quality of the pond. Empirically determined activities were evaluated by comparing them with apparent values estimated from the annual change in the concentration of nitrogenous compounds. Nitrification activity in both sediment and water samples was often found to be higher than denitrification activity. The contribution of nitrification activity in water to that in the pond as a whole was estimated to be higher than that in sediment, while the opposite was the case with denitrification activity.View full abstractDownload PDF (1046K) -
XIAOHUI LEI, NORIO SUGIURA, TAKAAKI MAEKAWAArticle type: ORIGINALS
2006 Volume 42 Issue 3 Pages 119-128
Published: 2006
Released on J-STAGE: March 10, 2018
JOURNAL FREE ACCESSThe nitrogen removal mechanism of soil trench systems is considered to involve coupling of nitrification and denitrification in different soil layers; however, the distribution and population sizes of the nitrifying and denitrifying bacteria present in it have not been clarified. The primary objective of this research was to spatially quantify the population size of ammonia-oxidizing bacteria (AOB) in a soil trench system in Sasagi (Tsukuba, Japan) by using potential nitrification activity and the real-time PCR method. From the potential nitrification activity analysis, it was found that nitrification occurred predominantly in the depths above 40 cm and decreased with an increase in the depth except at the 10-cm depth. AOB were found at all depths by real-time PCR except at the depths of 50 cm and 60 cm, which was explained by the very low saturated conductivity and high bulk density unsuitable for the growth of AOB. At depths above 40 cm, the AOB population size estimated by potential nitrification activity and the real-time PCR method had nearly the same tendency to decrease with an increase in the depth except at the 10-cm depth. The vertical distribution of the total bacteria was also estimated by real-time PCR. Moreover, the population sizes of AOB and total bacteria increased near and below the depth of 70 cm where influent flows in.View full abstractDownload PDF (4102K) -
YINGJUN CHENG, YUSUKE WATANEBE, SEN QIAO, TOICHIRO KOYAMA, KENJI FURUK ...Article type: ORIGINALS
2006 Volume 42 Issue 3 Pages 129-137
Published: 2006
Released on J-STAGE: March 10, 2018
JOURNAL FREE ACCESSSome operational problems remain unsolved for the conventional activated sludge (CAS) process, such as the large space requirement, high operational cost and large excessive sludge production. Swim-bed technology using a novel acrylic-fiber material biofringe (BF) material for biomass attachment is considered as a solution to some of these problems. In lab-scale tests, the CAS and BF processes were operated in parallel while contaminant removal efficiencies and sludge productions were compared. The study was conducted in two runs with BOD volumetric loading rates of 0.5 kg-BOD/m3/d for the Run I and 1.0 kg-BOD/m3/d for the Run II, corresponding to hydraulic retention times of 7.2 h and 3.6 h, respectively. Overall, superior contaminant removal efficiencies were demonstrated for the BF process. Average COD removal efficiencies for the BF and CAS processes in Run I were 92% and 86%, respectively, and in Run II, 90% and 83%, respectively. High nitrification efficiencies were obtained for both processes throughout the study; however, during Run II, the BF process had a significantly improved nitrogen removal efficiency of 44% versus 34% for the CAS process. After increasing the volumetric loading rates in Run II, sludge washout occurred in the CAS process, while high biomass levels were maintained in the BF process, demonstrating the retention capacity of the BF carrier. Sludge yields were calculated to be 0.12 kg-MLSS/kg-CODremoved for the CAS process versus 0.081 kg-MLSS/kg-CODremoved for the BF process in Run I and 0.22 kg-MLSS/kg-CODremoved versus 0.12 kg-MLSS/kg-CODremoved, in Run II, respectively. A large amount of protozoa and metazoa were found in the BF process, which could have contributed to the observed reduction of excess sludge.View full abstractDownload PDF (1731K) -
TRAN THI HIEN HOA, LUONG NGOC KHANH, LIU ZHIJUN, TAKAO FUJII, JOSEPH D ...Article type: ORIGINALS
2006 Volume 42 Issue 3 Pages 139-149
Published: 2006
Released on J-STAGE: March 10, 2018
JOURNAL FREE ACCESSThe use of a biomass carrier is preferred for the cultivation of slowly growing anammox sludge. In this study, PVA gel was selected as a biomass carrier for anammox sludge and applied in a fluidized-bed reactor (FBR). A recycle pump was used to induce a flow rate of 6 － 7 l/min to maintain fluidized bed conditions. Both influent NH4-N and NO2-N concentrations were increased stepwise to 300 mg N/l. With hydraulic retention times (HRTs) from 16 h to 9 h in phase 1, NH4-N and NO2-N removal efficiencies were about 81% and 92%, respectively. With HRTs from 9 h to 4 h in phase 2, NH4-N removal efficiency was 77% and NO2-N removal efficiency was 89%. The removal rates of ammonium and total nitrogen in phase 1 increased up to 0.71 and 1.35 kg N/m3/d, respectively. Maximum removal rates of ammonium and total nitrogen in phase 2 increased quickly up to 1.5 and 3.0 kg N/m3/d, respectively. Ratios of T-N removal, NO2-N removal, and NO3-N production to NH4-N removal during phase 1 were 1.91:1.12:0.22. These ratios during phase 2 were 1.96:1.18:0.21. The color of the PVA-gel beads changed from white to brownish red, which is consistant with anammox bacteria. By the Denaturing Gradient Gel Electrophoresis (DGGE) method, both KSU-1 and KU-2 anammox strains were detected with KSU-1 in dominance in the FBR process.View full abstractDownload PDF (1998K) -
HIROSHI YAMAZAKI, RIE SUZUKI, YASUTOSHI SHIMIZU, YOSHITAKA EBIE, YUHEI ...Article type: ORIGINALS
2006 Volume 42 Issue 3 Pages 151-157
Published: 2006
Released on J-STAGE: March 10, 2018
JOURNAL FREE ACCESSEffects of high circulation ratio on nitrification and denitrification processes were investigated. In bench-scale Johkasou model system, increase in hydraulic retention time was effective for BOD removal. However, T－N removal efficiency was not increased because of NO2＋3－N remaining in effluent. Because both nitrification and denitrification rates were high, effluent concentration of T－N should depend on the operational parameter, circulation ratio. Therefore, circulation ratio was set from 0 to 7 in bench-scale systems although circulation ratio is normally set from 3 to 4 empirically. In the case of higher circulation ratio such as 6, denitrification was affected by the large volume of circulation water causing increase in dissolved oxygen in anaerobic tank. Meanwhile, lower circulation ratio decreased dilution rate of influent domestic wastewater and increased NH4－N concentration in the inlet water of aerobic tank. The effect of NH4－N concentration on ammonia oxidation rate was investigated by batch test, and it was found that ammonia oxidation rate was not affected by NH4－N concentration ranging from 5.6 to 11.25 mg l－1. According to these results, optimum circulation ratio should be 5. The effect of high circulation ratio was also demonstrated in the full scale Johkasou systems.View full abstractDownload PDF (1010K)
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