treatment of distillery spentwash in asbr

TREATMENT OF DISTILLERY WASTEWATER IN ANAEROBIC

SEQUENCING BATCH REACTOR

K.AKIL, M.E., Ph.D.,Assistant Professor of Civil Engg.,

Hindusthan College of Engineering and Technology.

Dr. S. JAYANTHI, M.E., Ph.D.,Associate Professor of Civil Engg.,

Government College of Technology.

R. RATHEESH KUMAR, & C. GIRIJA B.Tech., PG Scholars, Government College of Technology.

INTRODUCTIONINTRODUCTION

• Distilleries are one of the most polluting industries generating large volumes of high strength wastewater

• On an average 8-15L of effluent is generated for every litre of alcohol produced (Saha et. al, 2005)

• In India, there are 319 industries producing 3.25 billion litres of alcohol and generating 40.4 billion litres of wastewater annually (Pant et. al, 2007)

INTRODUCTIONINTRODUCTION

• Alcohol production in distilleries consists of four main steps viz. feed preparation, fermentation, distillation and packaging (Satyawali et.al, 2008)

• The liquid waste from alcohol production can mainly be divided into: stillage from separation and distillation process, cleaning water from fermenters, distillation columns and floors and refrigeration water from cooling after distillation.

IMPACTS OF DISTILLERY IMPACTS OF DISTILLERY SPENT WASHSPENT WASH

• Molasses spent wash has very high levels of BOD, COD as well as high potassium, phosphorus and sulphate content (Pathade, 1999, Wilkie et. al, 2000)

• contains low molecular weight compounds such as lactic acid, glycerol, ethanol and acetic acid (Wilkie et. al, 2000)

• contains 2% of a dark brown pigment called melanoidins that impart colour to the spent wash (Kalavathi et.al, 2001)


• Melanoidins are toxic to many microorganisms involved in wastewater treatment (Sirianuntapiboon et.al, 2004)

• High COD, total nitrogen and total phosphate content of the distillery effluent may result in the eutrophication of the natural water bodies (Kumar et. al, 1997, FitzGibbon et. al, 1998)


• coloured components reduce sunlight penetration in rivers and lakes which in turn decrease both photosynthetic activity and dissolved oxygen concentration affecting aquatic life.

• land disposal of distillery effluent can lead to groundwater contamination (Joshi, 1999 & Jain et. al, 2005). Undiluted effluent has toxic effect on fishes and other aquatic organisms.


• Spent wash is reported to inhibit seed germination, reduce soil alkalinity, cause soil manganese deficiency and damage agricultural crops (Agarwal et. al,1994 & Kannan et.al, 2008)

ANAEROBIC SEQUENCING ANAEROBIC SEQUENCING BATCH REACTORSBATCH REACTORS

Anaerobic sequencing batch reactors (ASBR) are reactors that operate in four cyclic steps: feed, reaction, settling and discharge.

Anaerobic sequencing batch reactors allow typical biological anaerobic metabolism from substrate consumption to methane and carbon dioxide production

FEEDFEED

The first step involves the addition of substrate to the reactor where the contents are continuously mixed to establish a close contact between the substrate and the bacteria for reaction.

The volume of substrate fed depends on a number of factors, including the desired hydraulic retention time (HRT), organic loading and expected

settling characteristics

(Ndon U.J. and Dague R.R.,1997)

REACTREACT

The mixing (may be continuous or intermittent) should however be gentle to avoid the disruption of bacterial flocs formation.

The length of the react period will depend on the required effluent quality and substrate characteristics

SETTLESETTLE

• At the end of reaction period, to enable the biomass to floc and settle, mixing of the contents is stopped.

• The required time for the settling step depends on biomass concentration, temperature and type of biomass (Ndon & Dague, 1997)

DECANTDECANT

• At the end of the settling step, decantation takes place.

• During effluent drawdown, microorganisms with poor settling characteristics are also removed from the reactor, leaving the heavier bacterial flocs (Sung & Dague 1995)

ADVANTAGES OF ASBRADVANTAGES OF ASBR

• Operational simplicity, • Efficient quality control of effluent and • Flexibility of use for both, low strength

and high strength wastewaters.

Distinct advantages of ASBR when compared to CSTR system include:

high biomass concentration,

a high degree of process flexibility, and

no requirement to apply a separate clarifier. (Ratusznei et. al, 2000)

DARK FERMENTATIONDARK FERMENTATION

Fermentative conversion of organic substrate to biohydrogen in the absence of light

Complex process accomplished by diverse group of bacteria similar to anaerobic conversion

DARK FERMENTATIONDARK FERMENTATION

Microorganisms hydrolyse complex organic substrates into monomers which are then converted to lower molecular weight organic acids and alcohols with the liberation of hydrogen gas by hydrogen producing bacteria

There is a need of inhibiting hydrogen consuming bacteria such as methanogens

ADVANTAGES OF DARK ADVANTAGES OF DARK FERMENTATIONFERMENTATION

High rate of H2 evolution

Convert organic substrates and sugar wastes

Produce valuable coproducts

Fermentation technology is cheap

STUDIES AT GCT ON STUDIES AT GCT ON ASBRASBR

• Seed sludge

The inoculum (Distillery sludge) was collected from the sludge recycling port in the biogas plant of a distillery at Erode.

• Substrate

The substrate consisted of the spent wash of a distillery at Udumalpet, Coimbatore.

CHARACTERISTICS OF CHARACTERISTICS OF DISTILLERY SPENT WASHDISTILLERY SPENT WASH

Characteristics Concentration

COD 93,000 mg/L

BOD 82,000 mg/L

Total solids 1,19,000 mg/L

Total suspended solids 42,200 mg/L

Total dissolved solids 70,800 mg/L

Total volatile solids 30,800 mg/L

Dissolved volatile solids 21,300 mg/L

Volatile fatty acids 3,586 mg/L

Sulphates 18,476 mg/L

pH 4.18

ASBR FOR METHANE ASBR FOR METHANE PRODUCTIONPRODUCTION

ASBR FOR HYDROGEN ASBR FOR HYDROGEN PRODUCTIONPRODUCTION

ASBR SEQUENCING ASBR SEQUENCING CHARACTERISTICS (4hr seq.)CHARACTERISTICS (4hr seq.)

Parameter Hydraulic Retention Time (HRT), hr

Seq. characteristics 72 48 24 16 12

No. of sequences per day 6 6 6 6 6

Length of sequence, hr 4 4 4 4 4

Vol. of feed per day, ml 1167 1750 3500 5250 7000

Vol. of feed per seq, ml 194.5 291.7 583.3 875 1166.7

Vol. decanted per day, ml 1167 1750 3500 5250 7000

Vol. decanted per seq, ml 194.5 291.7 583.3 875 1166.7

Feeding time, min 10 10 10 10 10

Reaction time, min 180 180 180 180 180

Settling time, min 40 40 40 40 40

Decanting time, min 10 10 10 10 10







Vol. of feed per seq, ml 291.75 437.5 875 1312.5 1750


Vol. decanted per seq, ml 291.75 437.5 875 1312.5 1750











Vol. of feed per seq, ml 389 583.3 1166.7 1750 2333.3


Vol. decanted per seq, ml 389 583.3 1166.7 1750 2333.3





ANALYTICAL METHODSANALYTICAL METHODS

• The major parameters analysed for monitoring the performance of the reactor included pH, Chemical oxygen demand (COD), Bio-chemical oxygen demand (BOD), Total Solids (TS), Total Volatile Solids (VS), Total Fixed Solids (FS), Total Suspended Solids (TSS), and Volatile Suspended Solids (VSS), Volatile Fatty Acids (VFA), Carbonate Alkalinity and Biogas production. All analysis was performed in accordance with Standard Methods

CONCLUSIONCONCLUSION

For industries using large quantities of water such as distilleries, it is essential to treat and reuse their wastewater.

ASBR can extensively be used for distillery wastewater treatment as an alternative for continuous systems owing to its superior biological solids retention and process control.

CONCLUSIONCONCLUSION

The emission standards can more easily be attained through control of the cycle duration and discharge operation of batch reactions, which allow for better effluent quality control.

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treatment of distillery spentwash in asbr

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