Control of filamentous bulking and interactions among sulfur oxidation-reduction and iron oxidation-reduction in activated sludge using an iron coagulant

1998 ◽  
Vol 38 (8-9) ◽  
pp. 9-17 ◽  
Author(s):  
Ryoko Yamamoto-Ikemoto ◽  
Saburo Matsui ◽  
Tomoaki Komori ◽  
Edja Kofi Bosque-Hamilton

The effect of iron coagulant on control of filamentous bulking and phosphate removal was investigated using a laboratory scale activated sludge process. Sulfate reduction was correlated to activated sludge bulking. When FeCl2 was added to the aeration tank, most of the phosphate was removed. Sulfate reduction and filamentous bulking were also suppressed. The addition of FeCl2 was also effective in suppressing phosphate release and sulfide production from wasted sludge. Interactions among sulfur oxidation-reduction and iron oxidation-reduction were examined in the batch experiments. When FeCl2 was added, iron reducing bacteria outcompeted sulfate reducing bacteria and iron oxidizing bacteria grew predominantly.

2002 ◽  
Vol 46 (1-2) ◽  
pp. 55-60 ◽  
Author(s):  
R. Yamamoto-Ikemoto ◽  
T. Komori ◽  
S. Matsui

Iron oxidation and reduction were examined using the activated sludge from a municipal plant. Iron contents of the activated sludge were 1–2%. Iron oxidation rates were correlated with the initial iron concentrations. Iron reducing rates could be described by the Monod equation. The effects of iron reducing bacteria on sulfate reduction, denitrification and poly-P accumulation were examined. Iron reduction suppressed sulfate reduction by competing with hydrogen produced from protein. Denitrification was outcompeted with iron reduction and sulfate reduction. These phenomena could be explained thermodynamically. Poly-P accumulation was also suppressed by denitrification. The activity of iron reduction was relatively high.


1998 ◽  
Vol 37 (4-5) ◽  
pp. 599-603 ◽  
Author(s):  
Ryoko Yamamoto-Ikemoto ◽  
Saburo Matsui ◽  
Tomoaki Komori ◽  
Edja. Kofi. Bosque-Hamilton

The interactions between filamentous sulfur bacteria (FSB), sulfate reducing bacteria (SRB) and poly-P accumulating bacteria (PAB) in the activated sludge of a municipal plant operated under anaerobic-oxic conditions were examined in batch experiments using return sludge (RAS) and settled sewage. Phosphate release and sulfate reduction occurred simultaneously under anaerobic conditions. SRB were more sensitive to temperature changes than PAB. SRB played an important role in the decomposition of propionate to acetate. When the sulfate reduction rates were high, there was a tendency for the maximum release of phosphate also to be high. This was explained by the fact that PAB utilized the acetate produced by SRB. Sulfur oxidizing bacteria were sensitive to temperature change. When the sulfate reduction rate was high, the sulfide oxidizing rate was also high and filamentous bulking occurred. The results showed that sulfate reduction was a cause of filamentous bulking due to Type 021N that could utilize reduced sulfur.


1991 ◽  
Vol 23 (4-6) ◽  
pp. 927-935 ◽  
Author(s):  
Ryoko Ikemoto Yamamoto ◽  
Tomoaki Komori ◽  
Saburo Matsui

Sulfate reduction in the activated sludge cultivated with glucose and peptone in the sequential batch reactor system and the continuous anaerobic-oxic system was examined. In both systems, sulfate reduction occurred. When the sulfate reduction ratio increased, Type 021N or Beggiatoa sp. grew in the sludge and settling characteristics became poor. These results suggested that sulfate reduction was a cause of growth of the filamentous bacteria which could utilize sulfide for the energy source. There was a tendency that the greater the sulfate reduction ratio was, the smaller the phosphate removal ratio was. As a result of batch experiments using the mixed liquor and the wall growing sludge, it was demonstrated that the sulfate reducing bacteria grown in the activated sludge mainly produced acetate from propionate and lactate. About 107~108 MPN of sulfate reducing bacteria grew in 1 g of the activated sludge and about 109 MPN grew in 1 g of the wall growing sludge.


2008 ◽  
Vol 58 (7) ◽  
pp. 1405-1413 ◽  
Author(s):  
Takahiro Yamashita ◽  
Ryoko Yamamoto-Ikemoto

Phosphorus removal and denitrification using iron and wood as electron donors were examined in a laboratory-scale biological filter reactor. Phosphorus removal and denitrification using iron and wood continued for 1,200 days of operation. Wood degradation by heterotrophic denitrification and iron oxidation by hydrogenotrophic denitrification occurred simultaneously. In the biofilm inside the wood, not only heterotrophic denitrification activity but also sulfate reduction and sulfur denitrification activities were recognized inside the wood, indicating that a sulfur oxidation-reduction cycle was established. Sulfate reduction and denitrification were accelerated with the addition of cellulose. Microbial communities of sulfate-reducing bacteria by PCR primer sets could be amplified in the biofilm in the reactors. The dissimilatory sulfite reductase gene and the 16S rRNA gene of six phylogenetic groups of SRB in the reactors were analyzed. Some SRB group-specific primers-amplification products were obtained inside the wood and around iron.


1996 ◽  
Vol 34 (5-6) ◽  
pp. 119-128 ◽  
Author(s):  
Ryoko Yamamoto-Ikemoto ◽  
Saburo Matsui ◽  
Tomoaki Komori ◽  
E. J. Bosque-Hamilton

Symbiosis and competition were examined among sulfate reducing bacteria (SRB), filamentous sulfur bacteria (FSB), denitrification bacteria (DNB) and poly-P accumulation bacteria (PAB) in the activated sludge of a municipal plant operated under anaerobic-oxic conditions. Batch experiments were carried out using settled sewage from the same plant as the substrate under several conditions. Under oxic conditions, both sulfate reduction and sulfide oxidation occurred simultaneously, making a symbiotic relationship of SRB and FSB for establishment of a sulfur cycle sustaining the energy requirements. Under anoxic conditions, denitrification was dominant because DNB outcompeted PAB and SRB for organic acids. Under anaerobic conditions, phosphate release and sulfate reduction occurred simultaneously. SRB produced for moles of acetate from four moles of propionate and/or unknown substances by reduction of three moles of sulfate. PAB competed with sulfate-reducing bacteria for organic acids such as propionate. However, PAB utilized acetate produced by SRB.


1994 ◽  
Vol 30 (11) ◽  
pp. 201-210 ◽  
Author(s):  
Ryoko Yamamoto-Ikemoto ◽  
Saburo Matsui ◽  
Tomoaki Komori

Effects of anoxic-oxic conditions on the growth of sulfate reduction, poly-P accumulation and filamentous sulfur bacteria were examined in the laboratory scale sequential batch reactors. In the anoxic-oxic conditions, denitrification bacteria are dominant. The growth of sulfate reducing bacteria and poly-P accumulating bacteria was suppressed. The number of sulfate reducing bacteria in the activated sludge was below 104 MPN/g MLSS, and the sulfate reduction rate was very low. Filamentous bulking was also suppressed. On the other hand, when nitrate was removed from the artificial wastewater, sulfate reducing bacteria could grow predominantly in the anaerobic conditions. The number of sulfate reducing bacteria was about 106∼107 MPN/g MLSS and the sulfate reduction rate increased (0.17 ∼ 0.21 g SO4/g MLSS·hr). Filamentous bacteria Type 021N increased over 103 cm/mg MLSS. Sodium molybdate was added to the artificial wastewater in order to prevent sulfate reduction. When the concentration of sodium molybdate increased to 980 mg/L, the number of sulfate reducing bacteria decreased to 103 ∼ 104 MPN/g MLSS and the sulfate reduction rate decreased. Filamentous bulking was completely suppressed in these conditions. These results show that sulfate reduction is a main trigger of the filamentous bulking due to Type 021N that can utilize reduced sulfur for an energy source.


2006 ◽  
Vol 54 (8) ◽  
pp. 111-119 ◽  
Author(s):  
N. Miyazato ◽  
R. Yamamoto-Ikemoto ◽  
S. Takamatsu

The growth of sulfate reducing bacteria (SRB) and filamentous sulfur bacteria was monitored on a laboratory scale in activated sludge reactors using acetate and peptone as the artificial wastewater. When the artificial wastewater contained acetate and peptone, filamentous bacteria increased in the sludge and the SVI values increased. There was a good correlation between sulfate reducing activity and sulfur oxidation activity in the produced sludge. The microbial community change of filamentous sulfur bacteria and sulfate reducing bacteria was analyzed using the fluorescent in situ hybridization (FISH) method. The tendency for the growth of filamentous sulfur bacteria Thiothrix eikelboomii following the growth of SRB was observed. The percentage of SRB385- hybridized cells and DNMA657-hybridized cells found in the total cell area increased from 2–3% to 7–10% when the filamentous bulking occurred.


1997 ◽  
Vol 35 (5) ◽  
pp. 293-299 ◽  
Author(s):  
Wendy R. Tyrrell ◽  
David R. Mulligan ◽  
Lindsay I. Sly ◽  
L. Clive Bell

The large number of wetlands treating mining wastewaters around the world have mostly been constructed in temperate environments. Wetlands have yet to be proven in low rainfall, high evaporation environments and such conditions are common in many parts of Australia. BHP Australia Coal is researching whether wetlands have potential in central Queensland to treat coal mining wastewaters. In this region, mean annual rainfall is < 650 mm and evaporation > 2 000 mm. A pilot-scale wetland system has been constructed at an open-cut coal mine. The system comprises six treatment cells, each 125 m long and 10 m wide. The system is described in the paper and some initial results presented. Results over the first fourteen months of operation have shown that although pH has not increased enough to enable reuse or release of the water, sulfate reduction has been observed in parts of the system, as shown by the characteristic black precipitate and smell of hydrogen sulfide emanating from the wetlands. These encouraging signs have led to experiments aimed at identifying the factors limiting sulfate reduction. The first experiment, described herein, included four treatments where straw was overlain by soil and the water level varied, being either at the top of the straw, at the top of the soil, or about 5 cm above the soil. The effect of inoculating with sulfate-reducing bacteria was investigated. Two controls were included, one covered and one open, to enable the effect of evaporation to be determined. The final treatment consisted of combined straw/cattle manure overlain with soil. Results showed that sulfate reduction did occur, as demonstrated by pH increases and lowering of sulfate levels. Mean pH of the water was significantly higher after 19 days; in the controls, pH was < 3.3, whereas in the treatments, pH ranged from 5.4 to 6.7. The best improvement in sulfate levels occurred in the straw/cattle manure treatment.


1999 ◽  
Vol 39 (7) ◽  
pp. 41-47 ◽  
Author(s):  
Satoshi Okabe ◽  
Hisashi Satoh ◽  
Tsukasa Itoh ◽  
Yoshimasa Watanabe

The vertical distribution of sulfate-reducing bacteria (SRB) in microaerophilic wastewater biofilms grown on fully submerged rotating disk reactors (RDR) was determined by the conventional culture-dependent MPN method and in situ hybridization of fluorescently-labelled 16S rRNA-targeted oligonucleotide probes for SRB in parallel. Chemical concentration profiles within the biofilm were also measured using microelectrodes for O2, S2-, NO3- and pH. In situ hybridization revealed that the SRB probe-stained cells were distributed throughout the biofilm even in the oxic surface zone in all states from single scattered cells to clustered cells. The higher fluorescence intensity and abundance of SRB probe-stained cells were found in the middle part of the biofilm. This result corresponded well with O2 and H2S concentration profiles measured by microelectrodes, showing sulfate reduction was restricted to a narrow anaerobic zone located about 500 μm below the biofilm surface. Results of the MPN and potential sulfate reducing activity (culture-dependent approaches) indicated a similar distribution of cultivable SRB in the biofilm. The majority of the general SRB probe-stained cells were hybridized with SRB 660 probe, suggesting that one important member of the SRB in the wastewater biofilm could be the genus Desulfobulbus. An addition of nitrate forced the sulfate reduction zone deeper in the biofilm and reduced the specific sulfate reduction rate as well. The sulfate reduction zone was consequently separated from O2 and NO3- respiration zones. Anaerobic H2S oxidation with NO3- was also induced by addition of nitrate to the medium.


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