A UASB bioreactor using silage as a carbon source to reduce sulfate

2011 ◽  
Vol 11 (2) ◽  
pp. 229-237 ◽  
Author(s):  
Winton Li ◽  
Susan A. Baldwin

Low cost-treatment for sulfate removal is required in many areas where potable water is scarce. The biggest challenge in biological treatment is finding an abundant low or no-cost carbon source. This work demonstrated for the first time that leachate from the agricultural byproduct silage can be used in an upflow anaerobic sludge-bed bioreactor to reduce sulfate for on-farm water treatment. The reactor ran continuously for approximately one year with an average silage leachate feed COD concentration of 4,471 ± 857 mg L−1, and sulfate feed concentrations varying from 1,253 to 2,081 mg L−1. The maximum sulfate reduction rate (SRR) of 9.75 ± 0.23 mmol (L day)−1 was achieved at the high sulfate influent concentration and the amount of organics consumed was between 80–90%. Sulfide levels in the UASB bioreactor were consistently high for most of the experiment, averaging 516.6 ± 188.5 mg L−1. Interestingly, during the last month of operation when sulfide concentrations were highest the SRR continued to increase. It was estimated that 36% of the silage leachate carbon was used directly for sulfate reduction.

1998 ◽  
Vol 38 (8-9) ◽  
pp. 317-324 ◽  
Author(s):  
Gong-Ming Zhou ◽  
Herbert H. P. Fang

This study was conducted to investigate the methanogenic and sulfidogenic activities of biomass in a UASB reactor treating wastewater containing benzoate (680 mg l−1) and sulfate (increased from 1080 to 2680 mg l−1) at 37°C and 12 hours of hydraulic retention. Results showed that after 120 days of acclimation, sludge consistently removed 99.5% of benzoate regardless of increased sulfate concentrations. Sulfidogenesis gradually out-competed methanogenesis during the acclimation phase, as indicated by the increase of sulfate-reducing efficiency (up to 99%) accompanied by the decrease of methane production. Overall sulfate removal efficiency was limited after the reactor had reached its maximum sulfate reduction rate of 2.1 g S (l d−1). Further increasing sulfate concentration from 1080 mg l−1 to 2680 mg l−1 lowered the sulfate-reducing efficiency from 85% to 39%. Flow of available electrons toward sulfidogenesis increased with the decrease of benzoate concentration, and was only slightly affected by the sulfate concentration or the benzoate/SO42−-S ratio.


Author(s):  
Hanna Virpiranta ◽  
Sanna Taskila ◽  
Tiina Leiviskä ◽  
Jouko Vepsäläinen ◽  
Jaakko Rämö ◽  
...  

Abstract The main goal of this study was to develop a cost-efficient biological method for the removal of sulfate from mining effluents in cold conditions. A consortium of cold-tolerant sulfate-reducing bacteria (SRB) was tested at 6 °C regarding the utilization of economically viable, low-cost carbon sources, i.e., whey, conditioned sewage sludge, and peat, in the removal of sulfate from synthetic mining water. Succinate was used as a reference carbon source. Of all the studied low-cost carbon sources, conditioned sewage sludge proved to be the most efficient. Nuclear magnetic resonance (NMR) spectroscopy revealed that sewage sludge contained propionic acid, which proved to be utilizable by SRB under cold conditions. Peat both adsorbed the sulfate and acted as a nutrient source in the sulfate reduction process. When whey was used as a carbon source, only a slight decrease in sulfate concentration was detected. Succinate was found to work in a truly predictable and efficient way as a carbon source in biological sulfate reduction, even at the lowest concentration tested. The use of conditioned sewage sludge increased the bacterial diversity in liquid cultivations significantly. However, the number of SRB was highest in the succinate cultivations.


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.


2001 ◽  
Vol 67 (2) ◽  
pp. 888-894 ◽  
Author(s):  
Jan Detmers ◽  
Volker Brüchert ◽  
Kirsten S. Habicht ◽  
Jan Kuever

ABSTRACT Batch culture experiments were performed with 32 different sulfate-reducing prokaryotes to explore the diversity in sulfur isotope fractionation during dissimilatory sulfate reduction by pure cultures. The selected strains reflect the phylogenetic and physiologic diversity of presently known sulfate reducers and cover a broad range of natural marine and freshwater habitats. Experimental conditions were designed to achieve optimum growth conditions with respect to electron donors, salinity, temperature, and pH. Under these optimized conditions, experimental fractionation factors ranged from 2.0 to 42.0‰. Salinity, incubation temperature, pH, and phylogeny had no systematic effect on the sulfur isotope fractionation. There was no correlation between isotope fractionation and sulfate reduction rate. The type of dissimilatory bisulfite reductase also had no effect on fractionation. Sulfate reducers that oxidized the carbon source completely to CO2 showed greater fractionations than sulfate reducers that released acetate as the final product of carbon oxidation. Different metabolic pathways and variable regulation of sulfate transport across the cell membrane all potentially affect isotope fractionation. Previous models that explained fractionation only in terms of sulfate reduction rates appear to be oversimplified. The species-specific physiology of each sulfate reducer thus needs to be taken into account to understand the regulation of sulfur isotope fractionation during dissimilatory sulfate reduction.


2004 ◽  
Vol 70 (3) ◽  
pp. 1608-1616 ◽  
Author(s):  
Ketil Bernt S�rensen ◽  
Donald E. Canfield ◽  
Aharon Oren

ABSTRACT The salinity responses of cyanobacteria, anoxygenic phototrophs, sulfate reducers, and methanogens from the laminated endoevaporitic community in the solar salterns of Eilat, Israel, were studied in situ with oxygen microelectrodes and in the laboratory in slurries. The optimum salinity for the sulfate reduction rate in sediment slurries was between 100 and 120‰, and sulfate reduction was strongly inhibited at an in situ salinity of 215‰. Nevertheless, sulfate reduction was an important respiratory process in the crust, and reoxidation of formed sulfide accounted for a major part of the oxygen budget. Methanogens were well adapted to the in situ salinity but contributed little to the anaerobic mineralization in the crust. In slurries with a salinity of 180‰ or less, methanogens were inhibited by increased activity of sulfate-reducing bacteria. Unicellular and filamentous cyanobacteria metabolized at near-optimum rates at the in situ salinity, whereas the optimum salinity for anoxygenic phototrophs was between 100 and 120‰.


2015 ◽  
Vol 14 (3) ◽  
pp. 399-410 ◽  
Author(s):  
R. P. Rodriguez ◽  
D. V. Vich ◽  
M. L. Garcia ◽  
M. B. A. Varesche ◽  
M. Zaiat

The production of low-pH effluent with sulfate and metals is one of the biggest environmental concerns in the mining industry. The biological process for sulfate reduction has the potential to become a low-cost solution that enables the recovery of interesting compounds. The present study analyzed such a process in a horizontal-flow anaerobic immobilized biomass (HAIB) reactor, employing ethanol as the carbon and energy source. Results showed that a maximal efficiency in the removal of sulfate and ethanol could only be obtained by reducing the applied sulfate load (225.1 ± 38 g m−3 d−1). This strategy led to over 75% of chemical oxygen demand (COD) and sulfate removal. Among the COD/SO42− studied ratios, 0.67 showed the most promising performance. The effluent's pH has naturally remained between 6.8 and 7.0 and the complete oxidation of the organic matter has been observed. Corrections of the influent pH or effluent recirculation did not show any significant effect on the COD and sulfate removal efficiency. Species closely related to strains of Clostridium sp. and species of Acidaminobacter hydrogenomorfans and Fusibacter paucivorans that can be related to the process of sulfate reduction were found in the HAIB reactors when the initial pH was 5 and the COD/SO42− ratio increased to 1.0.


2014 ◽  
Vol 68 (5) ◽  
Author(s):  
Hesam Kamyab ◽  
Mohd Fadhil Md Din ◽  
Chew Lee Tin ◽  
Mohanadoss Ponraj ◽  
Mohammad Soltani ◽  
...  

Algae are well known photosynthetic organisms that are able to grow at various environmental conditions. Microalgae and macrophytes are two categories of algae generally having similar biological activities with several industrial advantages. In recent years, micro and macro algae have been increasingly used as animal fodder supplements for farm animals. The main aim of this study is to propose the micro and macroalgae obtained from Palm Oil Mill Effluent (POME) waste water discharge as a promising low-cost-treatment and high-energy method for harvesting the nutritional supplements in order to enhance the animal feedstock production. The mixed micro and macro algal sample was collected from POME and Desa Bakti river. Then it was characterized for nutritional content as appropriate animal feed stock by diluting POME to various concentrations (0, 250, 500, 100 mg/L) in order to enhance their growth and to increase its nutritional value. It was found that a maximum of 23% COD reduction rate was obtained, while the COD concentration above 500 mg/L affected the growth of biomass. The potential use of algae as cheapest aquaculture diets can be considered to be as appropriate source for overcoming the problem of food scarcity and thereby minimizing the negative environmental impacts.


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.


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