scholarly journals Psychrophilic anaerobic treatment of low strength wastewaters

1999 ◽  
Vol 39 (5) ◽  
pp. 203-210 ◽  
Author(s):  
Salih Rebac ◽  
Jules B. van Lier ◽  
Piet Lens ◽  
Alfons J. M. Stams ◽  
Freddy Dekkers ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Volatile Fatty Acids ◽  
Oxygen Demand ◽  
Granular Sludge ◽  
Anaerobic Treatment ◽  
Cod Removal ◽  
High Rate ◽  
Organic Loading Rate ◽  
Substrate Conversion ◽  
Low Strength

Psychrophilic (2 to 20°C) anaerobic treatment of low strength synthetic and malting wastewater was investigated using a single and two module expanded granular sludge bed (EGSB) reactor system. The chemical oxygen demand (COD) removal efficiencies found in the experiments exceeded 90 % in the single module reactor at an organic loading rate up to 12 g COD dm−3 day−1 and a HRT of 1.6 h at 10-12°C ambient temperature using influent concentrations ranging from 500 to 800 mg COD dm−3. When a two module EGSB system was used at the temperature range 10-15°C, soluble COD removal and volatile fatty acids removal of 67-78% and 90-96% were achieved, respectively, and an OLR between 2.8-12.3 kg COD m−3 day−1 and a HRT of 3.5 h. The second module serves mainly as a scavenger of non-degraded volatile fatty acids (VFA) from the first module. The optimal temperatures for substrate conversion of reactor sludge, after it has been exposed to long term psychrophilic conditions, were similar to those of the original mesophilic inoculum. The specific activities of the sludge in the reactor increased in time by a factor 3, indicating enrichment of methanogens and acetogens even at low temperatures. By adapting the process design to the expected prevailing conditions inside the reactor, the loading potentials and overall stability of the anaerobic high-rate process may be distinctly improved under psychrophilic conditions. The results obtained clearly reveal the big potentials of anaerobic wastewater treatment under low ambient (10-12°C) temperature conditions for low strength wastewaters, very likely including domestic sewage.

Anaerobic treatment of landfill leachate by sulfate reduction

2000 ◽  
Vol 41 (3) ◽  
pp. 239-246 ◽  
Author(s):  
J.G. Henry ◽  
D. Prasad
Keyword(s):  
Landfill Leachate ◽  
High Surface ◽  
High Strength ◽  
Anaerobic Treatment ◽  
Cod Removal ◽  
Sulphate Reduction ◽  
High Rate ◽  
Organic Loading Rate ◽  
Filter Performance ◽  
Low Strength

The present study was conducted to investigate the effectiveness of the sulphate-reduction pathway in the anaerobic treatment of landfill leachate. The effects of several COD/SO4 ratios (keeping COD constant) and loadings on anaerobic filter performance were studied and compared with the results from anaerobic filters which followed the methanogenic pathway. Results indicated that the treatability of leachate by sulphate reducing bacteria (SRB) was dependent upon the leachate strength. With high strength leachate (COD=15000 mg/L) from the Keele Valley Landfill, it was found that at lower COD/SO4 ratios (≤1.6) toxic conditions developed in the system that were more inhibitory to the SRB than to the methane producing bacteria (MPB). As the COD/SO4 ratio increased, methanogenesis predominated. No predominance of SRB occurred at any COD/SO4 ratio with high strength leachate. The highest COD removal achieved was about 70% of which 20% was accomplished by the SRB at a COD/SO4 ratio of 1.6 and an organic loading rate (OLR) of 4 kg COD/m3.d. With low strength leachate (COD=1500-3300 mg/L) from the Brock West Landfill, and a COD/SO4 ratio <1, SRB became predominant. In these anaerobic filters in which SRB were predominant, the SRB reduced the COD as well as the MPB could. Sulphide inhibition did not take place at any loading in units treating low strength leachate. Consequently, both SRB and MPB should function at COD/SO4 ratios between 1 and 3. About 60% COD removal was achieved at a loading of 2.8 kg COD/m3.d and a COD/SO4 ratio of 1.0. However at a loading of 6 kg COD/m3.d only 27% COD removal was achieved, all of it through the sulphate-reduction pathway. These OLR values are comparable to those applied in systems where methanogenesis was dominant. It was also observed that once the methanogens were established in the units, it was not possible to displace them completely. However, where methanogenesis had not been previously established, it was found that sulphate-reduction could be the sole pathway for COD removal. From this study, it can be concluded that there is no advantage to the sulphate-reduction pathway in the anaerobic treatment of landfill leachate. The other options for increasing the loadings, i.e. the use of high surface/volume filter media (to achieve higher biomass concentrations) or high rate systems are likely to be more successful.

High rate thermophilic anaerobic wastewater treatment in compartmentalized upflow reactors

1994 ◽  
Vol 30 (12) ◽  
pp. 251-261 ◽  
Author(s):  
J. B. van Lier ◽  
F. Boersma ◽  
M. M. W. H. Debets ◽  
G. Lettinga
Keyword(s):  
Wastewater Treatment ◽  
Volatile Fatty Acids ◽  
Granular Sludge ◽  
Anaerobic Treatment ◽  
High Rate ◽  
Organic Loading Rate ◽  
Reactor Performance ◽  
Operation Performance ◽  
Granulation Process ◽  
Typical Sequence

Thermophilic anaerobic treatment of acidified and partially acidified wastewater was studied using Upflow Staged Sludge Bed (USSB) reactors. Reactors were composed of various compartments of which each was equipped with a gas-solid separator. This novel approach for thermophilic wastewater treatment led to a reduction or even elimination of major biological and physical limitations of conventional high rate thermophilic conversion processes. The main achievements of the plugflow reactor were i) very low concentrations of volatile fatty acids (VFA) in the effluent, ii) a high degree of sludge retention, and iii) stable reactor performance. The start-up of the reactors was done with either ‘crushed’ mesophilic granular sludge (MGS) or the digested organic fraction of municipal solid waste (OFMSW) as inoculum. A mixture of VFA and a mixture of sucrose-VFA were used as feed. A good operation performance was achieved within 1 month, and the granulation process of the thermophilic biomass was clearly visible after 1-1.5 months of operation. Within 2-3 months, the organic loading rate could be increased up to 100 kg sucrose-VFA-COD m−3 day−1 with a COD removal efficiency exceeding 90% at a HRT of 2-2.5 h. No significant wash-out of the thermophilic biomass was observed despite the extreme biogas load of 40-50 m3 m−3 reactor day. A certain percentage of sucrose was essential for the thermophilic granulation process; in the reactors treating solely the VFA mixture almost no granules were formed. Nevertheless, also in the latter reactors a satisfactory biomass hold up was observed despite the disperse nature of the sludge. The advantage of using compartmentalized reactors was clearly demonstrated under extreme loading conditions. A typical sequence in the degradation of the partially acidified substrate was found. In the first compartment sucrose was converted, followed by the conversion of butyrate and acetate in the next compartments. Propionate was the most difficult intermediate to degrade, but in the last compartments even this fatty acid was degraded almost completely.

scholarly journals Anaerobic treatment of high-sulfate wastes

1986 ◽  
Vol 13 (4) ◽  
pp. 423-428 ◽  
Author(s):  
Jan A. Oleszkiewicz ◽  
Barry L. Hilton
Keyword(s):  
Fatty Acids ◽  
Volatile Fatty Acids ◽  
Cheese Whey ◽  
Oxygen Demand ◽  
Anaerobic Treatment ◽  
Pulp And Paper ◽  
Anaerobic Sludge ◽  
Dairy Wastes ◽  
High Sulfate ◽  
Cooking Liquor

Six parallel upflow anaerobic sludge bed reactors were operated at chemical oxygen demand (COD) loads from 3 to 10 kg COD/(m3∙d). Four reactors (R1–R4) were fed sodium sulfate at loads of 1–3 kg S-SO4/(m3∙d). Reactors R1 and R2 were fed spent cheese whey with R1 being operated in an unstripped and R2 in a stripped mode. At COD loads below 5 kg/(m3∙d), the removal in R1 was 60–80% COD and generally trailed R2 by a margin of 0–15%. At higher COD loads and at higher SO4/COD ratios, the performance of R1 deteriorated significantly. A similar situation was found in the pair R3 (unstripped) and R4 (stripped), which was fed a mixture of spent whey and sulfite cooking liquor. Reactors R5 and R6 were subjected to the same feed as R3 and R4, but no sulfate was added. A comparison of R4 with R6 indicated slightly lower COD removal in R4 with similar amounts of volatile fatty acids accumulating in both reactors in cases of overloading. Key words: anaerobic treatment, sulfides, methanogenesis, inhibition, sludge bed reactor, dairy wastes, pulp and paper wastes, sulfate reduction.

Hybrid reactor performance in pentachlorophenol (pcp) removal by anaerobic granules

2001 ◽  
Vol 44 (4) ◽  
pp. 137-144 ◽  
Author(s):  
M. De Almeida Prado Montenegro ◽  
E. De Mattos Moraes ◽  
H. Moreira Soares ◽  
R. Filomena Vazoller
Keyword(s):  
Fatty Acids ◽  
Volatile Fatty Acids ◽  
Culture Media ◽  
Biogas Production ◽  
Removal Rate ◽  
Oxygen Demand ◽  
Granular Sludge ◽  
Concentration Addition ◽  
Hybrid Reactor ◽  
Reactor Performance

The present research aimed at evaluating pentachlorophenol (PCP) degradation in a hybrid reactor supplied with a mixture of fatty acids (propionic, butyric, acetic and lactic) and methanol. The performance of the reactor is remarkably stable and efficient during PCP additions at range of 2.0 to 21.0 mg/L. The reduction of chemical oxygen demand (COD) was around 97% and methane was found to be 86% in the biogas production. The efficiency of volatile fatty acids breakdown was 93%, 64% and 74% respectively for butyric, propionic and acetic. PCP total removal of more than 99% was reached by granular sludge activities formed during 21 months of reactor operation. Methanogenic microorganisms predominance was noticed with 105 to 106 cells/mL during enumeration on methanol or lactate added to sulfate culture media. The removal rate was 1.07 mg PCP · g−1 VS · d−1 during the highest PCP concentration addition.

Anaerobic baffled reactor treatment of biodiesel-processing wastewater with high strength of methanol and glycerol: reactor performance and biogas production

2011 ◽  
Vol 65 (5) ◽  
Author(s):  
Darin Phukingngam ◽  
Orathai Chavalparit ◽  
Dararat Somchai ◽  
Maneerat Ongwandee
Keyword(s):  
Chemical Oxygen Demand ◽  
Volatile Fatty Acids ◽  
Biogas Production ◽  
Oxygen Demand ◽  
Anaerobic Treatment ◽  
Organic Loading Rate ◽  
Organic Loading ◽  
Reactor Performance ◽  
Electron Microscopic ◽  
Anaerobic Baffled Reactor

AbstractBiodiesel-processing factories employing the alkali-catalyzed transesterification process generate a large amount of wastewater containing high amount of methanol, glycerol, and oil. As such, wastewater has high potential to produce biogas using anaerobic treatment. The aim of this research was to investigate the performance of an anaerobic baffled reactor for organic removal and biogas production from biodiesel wastewater. The effect of different organic loading rates, varying from 0.5 kg m−3 d−1 to 3.0 kg m−3 d−1 of chemical oxygen demand, was determined using three 22 L reactors, each comprising five separate compartments. Wastewater was pretreated with chemical coagulants to partially remove oil prior to experimentation. Results show that the anaerobic baffled reactor operated at 1.5 kg m−3 d−1 of chemical oxygen demand and ten days of hydraulic retention time provided the best removal efficiencies of 99 % of chemical oxygen demand, 100 % of methanol, and 100 % of glycerol. Increasing the organic loading rate over 1.5 kg m−3 d−1 of chemical oxygen demand led to excessive accumulation of volatile fatty acids thereby making the pH drop to a value unfavorable for methanogenesis. The biogas production rate was 12 L d−1 and the methane composition accounted for 64–74 %. Phase-separated characteristics revealed that the highest chemical oxygen demand removal percentage was achieved in the first compartment and the removal efficiency gradually decreased longitudinally. A scanning electron microscopic study indicated that the most predominant group of microorganisms residing on the external surface of the granular sludge was Methanosarcina.

Treatment of Low-Strength Wastewater Using an Anaerobic Baffled Reactor at Low Temperature

2013 ◽  
Vol 325-326 ◽  
pp. 822-826
Author(s):  
Zong Lian She ◽  
Xiao Hui Fu ◽  
Jian Wu ◽  
En Shi ◽  
Lai Li Zhao ◽  
...  
Keyword(s):  
Low Temperature ◽  
Loading Rate ◽  
Oxygen Demand ◽  
Granular Sludge ◽  
Organic Loading Rate ◽  
Scanning Electron Micrographs ◽  
Organic Loading ◽  
Microbial Composition ◽  
Anaerobic Baffled Reactor ◽  
Low Strength

Treatment of low-strength wastewater of chemical oxygen demand (COD) around 500-1500 mg/L was studied in a 100 L capacity laboratory scale anaerobic baffled reactor (four compartments) at low temperature (17 oC-25 oC). The reactor was operated at influent COD concentrations of 1500, 1000 and 500 mg/L and hydraulic retention times (HRTs) of 24, 12 and 8 h, with the average COD removals changing from 94% to 83%. Compartment-wise studies of various parameters revealed that if the organic loading rate (OLR) was larger, the initial compartment played significant role in the removal of organics. The examinations of scanning electron micrographs (SEM) indicated that the microbial composition of granular sludge were obviously different in four compartments.

Performance and stability of an expanded granular sludge bed reactor modified with zeolite addition subjected to step increases of organic loading rate (OLR) and to organic shock load (OSL)

2017 ◽  
Vol 77 (1) ◽  
pp. 39-50 ◽  
Author(s):  
T. Pérez-Pérez ◽  
I. Pereda-Reyes ◽  
E. Pozzi ◽  
D. Oliva-Merencio ◽  
M. Zaiat
Keyword(s):  
Volatile Fatty Acids ◽  
Loading Rate ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Stable Process ◽  
Oxygen Demand ◽  
Granular Sludge ◽  
Swine Wastewater ◽  
Organic Loading Rate ◽  
Organic Loading ◽  
Microbial Composition

Abstract This paper shows the effect of organic shock loads (OSLs) on the anaerobic digestion (AD) of synthetic swine wastewater using an expanded granular sludge bed (EGSB) reactor modified with zeolite. Two reactors (R1 and R2), each with an effective volume of 3.04 L, were operated for 180 days at a controlled temperature of 30 °C and hydraulic retention time of 12 h. In the case of R2, 120 g of zeolite was added. The reactors were operated with an up-flow velocity of 6 m/h. The evolution of pH, total Kjeldahl nitrogen, chemical oxygen demand (COD) and volatile fatty acids (VFAs) was monitored during the AD process with OSL and increases in the organic loading rate (OLR). In addition, the microbial composition and changes in the structure of the bacterial and archaeal communities were assessed. The principal results demonstrate that the presence of zeolite in an EGSB reactor provides a more stable process at higher OLRs and after applying OSL, based on both COD and VFA accumulation, which presented with significant differences compared to the control. Denaturing gradient gel electrophoresis band profiles indicated differences in the populations of Bacteria and Archaea between the R1 and R2 reactors, attributed to the presence of zeolite.

scholarly journals High-Rate Anaerobic Treatment of Wastewater at Low Temperatures

1999 ◽  
Vol 65 (4) ◽  
pp. 1696-1702 ◽  
Author(s):  
Gatze Lettinga ◽  
Salih Rebac ◽  
Sofia Parshina ◽  
Alla Nozhevnikova ◽  
Jules B. van Lier ◽  
...  
Keyword(s):  
Low Temperatures ◽  
Oxygen Demand ◽  
Granular Sludge ◽  
Anaerobic Treatment ◽  
High Rate ◽  
Degradation Rates ◽  
In Series ◽  
Propionate Oxidation ◽  
Stage System ◽  
Specific Degradation

ABSTRACT Anaerobic treatment of a volatile fatty acid (VFA) mixture was investigated under psychrophilic (3 to 8°C) conditions in two laboratory-scale expanded granular sludge bed reactor stages in series. The reactor system was seeded with mesophilic methanogenic granular sludge and fed with a mixture of VFAs. Good removal of fatty acids was achieved in the two-stage system. Relative high levels of propionate were present in the effluent of the first stage, but propionate was efficiently removed in the second stage, where a low hydrogen partial pressure and a low acetate concentration were advantageous for propionate oxidation. The specific VFA-degrading activities of the sludge in each of the modules doubled during system operation for 150 days, indicating a good enrichment of methanogens and proton-reducing acetogenic bacteria at such low temperatures. The specific degradation rates of butyrate, propionate, and the VFA mixture amounted to 0.139, 0.110, and 0.214 g of chemical oxygen demand g of volatile suspended solids−1 day−1, respectively. The biomass which was obtained after 1.5 years still had a temperature optimum of between 30 and 40°C.

Anaerobic treatment of a municipal landfill leachate

1997 ◽  
Vol 43 (10) ◽  
pp. 937-944 ◽  
Author(s):  
Jean-Claude Frigon ◽  
Jean-Guy Bisaillon ◽  
Gilles Paquette ◽  
Réjean Beaudet
Keyword(s):  
Landfill Leachate ◽  
Growth Parameters ◽  
Oxygen Demand ◽  
Anaerobic Treatment ◽  
Cod Removal ◽  
Organic Loading Rate ◽  
Oil And Grease ◽  
Municipal Landfill ◽  
Fixed Film ◽  
Film Reactor

Leachate from a municipal landfill site was treated in a laboratory using fixed-film cultures under anaerobic conditions. Serum-bottle cultures were used for optimization of the growth parameters. The reduction of the chemical oxygen demand (COD) of the leachate was faster at 29 °C compared with lower temperatures. Gradual acclimation of the microbial population to temperatures as low as 4 °C considerably increased the rate of COD removal at these temperatures. Addition of supplements to the leachate was not needed and it was not necessary to adjust the pH (5.9) for optimal COD reduction. Continuously fed reactors were also used to treat the leachate. The maximum organic loading rate of the reactor at 22 °C to obtain 85% COD removal was 2.1 kg COD∙m−3∙day−1, which corresponded to an hydraulic retention time of 1.5 days. After treatment under these conditions, the toxicity (Microtox method) of the leachate was completely eliminated and the required quality standards were met for iron, oil and grease, and phenols. The fermentative microorganisms in the biofilm of the reactor were evaluated to 4.6 × 107cells∙cm−2and identified as Streptococcus gallinarum, Clostridium glycolicum, Clostridium bifermentans or sadallii, Citrobacter amalonaticus, Bacteroides capillosus, and Eubacterium sp.Key words: anaerobic treatment, landfill, leachate, growth parameters, fixed-film reactor, microbiology.

Anaerobic Treatment of Polyethylene Terephthalate (PET) Wastewater from Lab to Full Scale

1999 ◽  
Vol 40 (8) ◽  
pp. 229-236 ◽  
Author(s):  
F. Fdz-Polanco ◽  
M. D. Hidalgo ◽  
M. Fdz-Polanco ◽  
P. A. García Encina
Keyword(s):  
Polyethylene Terephthalate ◽  
Loading Rate ◽  
Treatment Plant ◽  
Textile Wastewater ◽  
Anaerobic Treatment ◽  
Cod Removal ◽  
Organic Loading Rate ◽  
Foam Formation ◽  
Organic Loading ◽  
Start Up

In the last decade Polyethylene Terephthalate (PET) production is growing. The wastewater of the “Catalana de Polimers” factory in Barcelona (Spain) has two main streams of similar flow rate, esterification (COD=30,000 mg/l) and textile (COD=4000 mg/l). In order to assess the anaerobic treatment viability, discontinuous and continuous experiments were carried out. Discontinuous biodegradability tests indicated that anaerobic biodegradability was 90 and 75% for esterification and textile wastewater. The textile stream revealed some tendency to foam formation and inhibitory effects. Nutrients, micronutrients and alkali limitations and dosage were determined. A continuous lab-scale UASB reactor was able to treat a mixture of 50% (v) esterification/textile wastewater with stable behaviour at organic loading rate larger than 12 g COD/l.d (0.3 g COD/g VSS.d) with COD removal efficiency greater than 90%. The start-up period was very short and the recuperation after overloading accidents was quite fast, in spite of the wash-out of solids. From the laboratory information an industrial treatment plant was designed and built, during the start-up period COD removal efficiencies larger than 90% and organic loading rate of 0.6 kg COD/kg VSS.d (5 kg COD/m3.d) have been reached.

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