Field experience with different systems for biomass accumulation in anaerobic reactor technology

Thanks to undeniable advantages as recovery of energy and a low sludge production, anaerobic wastewater treatment has received recognition in the last decade. However due to the slow methanogenic growth, inreactor biomass accumulation is essential to maintain high loading rates. Indeed wash-out of biomass is one of the main problems encountered in the anaerobic treatment of industrial effluents. A broad scoped overview of the different reactor technologies is given each with its proper biomass accumulation system. All of them are founded on two basic mechanisms for biomass accumulation: separation and retention. Settling (Anaerobic Contact reactor), ultrafiltration and flotation (FlotametP) are the techniques used to separate externally the biomass from the effluent after which the biomass can be recirculated to the anaerobic reactor. Concentration of biomass can also be achieved by attachment to a mobile (Fluidized Bed reactor) or a static carrier with possible entrapment in its macroporous structure (Anaerobic Filter reactor). The UASB-reactor incorporates retention as well as separation. By stimulating granular growth, biomass is accumulated in the lower part of the reactor. A three phase separator at the top of the reactor contributes to the final clarification of the effluent. Hybrid reactors eventually combine different biomass accumulation mechanisms: granulation, external biomass separation (Upflow Anaerobic Contact reactor) and fixation (Upflow Anaerobic Contact Filter reactor).

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Two-stage UASB concept for treatment of domestic sewage including sludge stabilization process

Water Science & Technology ◽

10.2166/wst.1995.0402 ◽

1995 ◽

Vol 32 (11) ◽

pp. 55-63 ◽

Cited By ~ 8

Author(s):

S. K. I. Sayed ◽

M. A. A. Fergala

Keyword(s):

Granular Sludge ◽

Domestic Sewage ◽

Conversion Ratio ◽

Uasb Reactor ◽

Treatment Efficiency ◽

Second Stage ◽

Sludge Stabilization ◽

Three Phase ◽

Phase Separator ◽

Uasb Reactors

A multi-target study was conducted to assess the feasibility of the UASB-reactor system for the anaerobic treatment of raw domestic sewage (low-strength complex wastewater; CODtot=200-700 mg/l and CODss=45-55% of CODtot) combined with sludge stabilization process under a moderate temperature of 18-20 °C. The study has produced a design of a modified Three-Phase Separator (TPS) to control the sludge retention inside the UASB reactors as well as the determination of design parameters of the treatment process viz. the hydraulic retention time (HRT), the potential period of loading the UASB reactors and the most convenient digestion time required for advanced sludge stabilization. The study was performed in a Two-Stage Flocculent-Granular-Sludge UASB-reactor system. The first stage consisted of two identical UASB reactors seeded with flocculent sludge and operated alternately (i.e. one reactor was fed while the other was unfed for the stabilization of the sludge). The second stage consisted of one UASB reactor seeded with granular sludge and was operated continuously. The feed period and the corresponding feedless period of the first stage were two days. The results study have shown that the removal efficiency of the COD increases considerably with the decrease of the HRT, as a treatment efficiency of 75% was achieved at HRT=10 h (8 h for Stage I and 2 h for Stage II), while the treatment efficiency was 84% at HRT=6 h (4 h for Stage I and 2 h for Stage II). In contrast to the above the extent of sludge stabilization (i.e. conversion into methane) for the first stage of the system was directly proportional to the HRT as 41% of the removed CODtot was converted into methane at HRT=8 h, the conversion ratio decreased to 28% at HRT=4 h. For the granular sludge (the second stage of the system), the conversion ratio of the removed CODtot into methane was almost stable in the range of 17-20%. The percentages CODpaper-filtered of the CODtot were 85-90% and 92-97% for the effluents of the first and second stages respectively with the conclusion that the modified Three-Phase Separator (TPS) has a satisfactory operational potential.

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Research for Operation Stability of TUSB Reactor and the Feasibility in Organic Wastewater Treatment

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.183-185.489 ◽

2011 ◽

Vol 183-185 ◽

pp. 489-494

Author(s):

Jin Liu ◽

Dong Wei Li ◽

Xian Ping Gao

Keyword(s):

Loading Rate ◽

Impact Load ◽

Removal Rate ◽

Uasb Reactor ◽

Two Phase ◽

Reactor Technology ◽

Operation Stability ◽

Cod Removal Rate ◽

Volumetric Loading ◽

Phase Separator

According to the design concept of UASB reactor with three-phase separator, a suite of self-made TUSB reactor was produced. The operational characteristics of the reactor were tested after the reactor completed start-up, and analyzed the factors that affected the COD removal rate. The results show that, as the load changes rapidly, although there was a short decline on removal efficiency; the system still can adapt to the changes quickly, and return to its original level; the load continually increases, then the removal rate tends to be constant; the same time as the volumetric loading rate increases, the gas yield is on the rise. It is proved that the reactor technology has the resistance to flow and anti-impact load capability; meantime it also shows that the high volumetric loading rate within the two-phase separation can retain the sludge, avoiding UASB sludge wastage washout under high-load operation.

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A novel application of an anaerobic membrane process in wastewater treatment

Water Science & Technology ◽

10.2166/wst.2005.0620 ◽

2005 ◽

Vol 51 (6-7) ◽

pp. 45-50 ◽

Cited By ~ 12

Author(s):

H.S. You ◽

C.C. Tseng ◽

M.J. Peng ◽

S.H. Chang ◽

Y.C. Chen ◽

...

Keyword(s):

Wastewater Treatment ◽

Anaerobic Treatment ◽

Synthetic Wastewater ◽

Uasb Reactor ◽

Anaerobic Sludge ◽

Membrane Process ◽

Chemical Cleaning ◽

Anaerobic Reactor ◽

Membrane Scaling ◽

Aerobic Reactor

The applications of membrane processes in anaerobic biological wastewater treatment still have some limitations due to severe membrane scaling and fouling, although they have been proven to achieve superior COD removal and biomass retention. An innovative anaerobic membrane process for wastewater treatment was conducted to control the membrane scaling problems. The process comprises an anaerobic reactor, an aerobic reactor, and a membrane separation tank. Anaerobic sludge from a full-scale UASB reactor treating food wastewater was inoculated to anaerobic and aerobic reactor to purify synthetic wastewater consisting of glucose and sodium acetate. The anaerobic reactor was operated in a sludge bed type without three-phase separator. The aerobic reactor can eliminate residual organics from the anaerobic reactor effluent using facultative microorganisms. To provide solid-liquid separation, hollow fiber ultrafiltration module was submerged in the separation tank. The results clearly show that the anaerobic membrane process combined methanogenic and aerobic COD reduction is a stable system. No fatal scaling was found after two months of operation even without chemical cleaning for the membrane. It was also found that inorganic precipitates formed in the aerobic reactor were reduced due to CO2 stripping in aerobic reactor. Another important finding was that the inorganic precipitates were entrapped into facultative aerobes floc. The ash/SS ratio of aerobes floc increased from 0.17 to 0.55 after 50 days of operation, which confirms this phenomenon. Based on our investigation, the new process can control scaling effectively to extend the membrane application in anaerobic treatment.

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Inhibition of methanogenic activity of starch-degrading granules by aromatic pollutants

Water Science & Technology ◽

10.2166/wst.1997.0320 ◽

1997 ◽

Vol 35 (8) ◽

pp. 247-253 ◽

Cited By ~ 3

Author(s):

Herbert H. P. Fang ◽

Ivan W. C. Lau ◽

Denis W. C. Chung

Keyword(s):

Chemical Industry ◽

Functional Group ◽

Anaerobic Treatment ◽

Upflow Anaerobic Sludge Blanket ◽

Uasb Reactor ◽

Anaerobic Sludge ◽

Aromatic Pollutants ◽

Methanogenic Activity ◽

Phenolic Pollutants ◽

Ic50 Values

The effects of nine common aromatic pollutants from chemical industry on the bioactivity of anaerobic granules were examined. The granules were obtained from an upflow anaerobic sludge blanket (UASB) reactor treating wastewater containing colloidal starch. The specific methanogenic activities (SMA) of granules were measured at 37°C in serum vials using 3000 mg/l of colloidal starch as substrate, plus individual pollutants at various concentrations. The toxicity was expressed by the IR50 and IC50 values, i.e. the toxicant/biomass ratio and concentration at which levels the granules exhibited only 50% of their original bioactivities. Results showed that in general the granules exhibited mild resistance to toxicity of aromatic pollutants, probably due to the granules' layered microstructure. The toxicities, which were dependent on the nature of chemical functional group, of the aromatic pollutants were in the following descending order: cresols > phenol > hydroxyphenols/phthalate > benzoate. There was only marginal difference between the toxicity of the steric isomers. For the seven phenolic pollutants, the more hydrophobic the functional group the higher the toxicity. The granules' resistance to toxicity suggested the plausibility of anaerobic treatment of wastewater from the chemical industry.

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Influence of a Three-Phase Separator Configuration on the Performance of an Upflow Anaerobic Sludge Bed Reactor Treating Wastewater from a Fruit-Canning Factory

Water Environment Research ◽

10.2175/106143006x111790 ◽

2007 ◽

Vol 79 (2) ◽

pp. 199-207 ◽

Cited By ~ 4

Author(s):

Rachbordin Wongnoi ◽

Warinthorn Songkasiri ◽

Chantaraporn Phalakornkule

Keyword(s):

Anaerobic Sludge ◽

Three Phase ◽

Phase Separator

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The Future of Three Phase Separator Control

10.2118/77891-ms ◽

2002 ◽

Cited By ~ 3

Author(s):

J.S. Charlton ◽

R.P. Lees

Keyword(s):

Three Phase ◽

The Future ◽

Phase Separator

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Application of the UASB-Reactor for Anaerobic Treatment of Paper and Board Mill Effluent

Water Science & Technology ◽

10.2166/wst.1985.0005 ◽

1985 ◽

Vol 17 (1) ◽

pp. 61-75 ◽

Cited By ~ 21

Author(s):

L H A Habets ◽

J H Knelissen

Keyword(s):

Waste Water ◽

Water Treatment ◽

Energy Savings ◽

Hydraulic Retention Time ◽

Waste Water Treatment ◽

Anaerobic Treatment ◽

Raw Material ◽

Uasb Reactor ◽

Seed Sludge ◽

Uasb Reactors

Within the holding of Bührmann-Tetterode NV, 7 Dutch paper and board mills are operating, all of them using mainly waste paper as raw material. While three of them completely closed their watercircuits, two other mills put into practice biological waste water treatment namely anaerobic and anaerobic/aerobic. Number 6 is realising an anaerobic plant this year and for number 7 research is still being carried out, dealing with several unfavourable aspects. In September 1981 research for anaerobic treatment (UASB reactors) was started. After good results had been achieved on laboratory scale (301), further investigations were started on semitechnical scale (50 m3). In both cases the anaerobic seed sludge granulated after a while and loadings up to 20 kg COD/m3.d could be handled. COD-removal was 70 per cent, even when the hydraulic retention time was only 2.5 hours. In April 1983 a 70 m3 practical scale UASB reactor was started up at the solid board mill of Ceres. In October 1983 a full scale plant was started up at Papierfabriek Roermond. This plant consists of a 1,000 m3 UASB reactor and a 70 m3 gasholder. It has been designed and constructed by Paques BV and is used for pretreatment of effluent, in order to reduce the loading of the activated sludge plant. Besides energy savings on the oxygen input, about 1 million m3/year of biogas is being generated and is used for steamproduction. Both plants are working satisfactorily. Investment costs appeared to be relatively low. At Ceres, pay-out time is 1.5 year, while at Papierfabriek Roermond waste water treatment is cheaper than before, although capacity is doubled.

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