N.D.M.V.P.SAMAJ’S

GUIDE BY

Prof. A. B. SANERACADEMIC YEAR 2013-2014

DISTILLERY SPENTWASH TREATMENT USING ACTIVATED SLUDGE PROCESS.

UNIVERSITY OF PUNE

PRESENT BYPACHPUTE AJAY L.

NERKAR JITENDRA R.VALVI BHASKAR

INTRODUCTION TO THE ACTIVATED-SLUDGE PROCESS

The process deals with the treatment of sewage (and industrial wastewater) and was developed around 1912-1914

Activated sludge is a biochemical process for treating sewage and industrial wastewater that uses air (or oxygen) and microorganisms to biologically oxidize organic pollutants, producing a waste sludge (or floc) containing the oxidized material

Atmospheric air or pure oxygen is bubbled through primary treated sewage (or industrial wastewater) and combined with organisms to develop a biological floc which reduces the organic content of the sewage

The combination of raw sewage and biological mass is commonly known as Mixed Liquor.

In all activated sludge plants, once the sewage (or industrial wastewater) has received sufficient treatment, excess mixed liquor is discharged into settling tanks and the treated supernatent is run off to undergo further treatment before discharge.

Mixed Liquor is a mixture of raw or settled wastewater and activiated sludge within an aeration tank in the activated sludge process

Mixed Liquor Suspended Solids (MLSS) is the concentration of suspended solids in the mixed liquor, usually expressed in milligrams per litre (mg/l)

TYPICAL TREATMENT PLANT

Mixed Liquor Suspended Solids

Returned Activated Sludge

Surplus Activated Sludge

Sludge Production

Sludge will accumulate in the activated-sludge process if it cannot be processed fast enough by an undersized sludge-handling facility.

The observed yield decreases as the SRT is increased due to biomass loss by more endogenous respiration. The yield is higher when no primary treatment is used, as more nbVSS remains in the influent wastewater(A-B).

WHY MEASURE MLSS

If MLSS content is too high

The process is prone to bulking and the treatment system becomes overloaded

This can cause the dissolved oxygen content to drop with the effect that organic matters are not fully degraded and biological 'die off‘

Excessive aeration required which wastes electricity

If MLSS content is too low

The process is not operating efficiently and is wasting energy

Typcial Control band 2,000 to 4,000 mg/l

To maintain high levels of treatment performance

The principal approaches to process control are (1) maintaining dissolved oxygen levels in the aeration tanks, (2) regulating the amount of return activated sludge (RAS), and (3) controlling the waste-activated sludge (WAS).

The parameter used most commonly for controlling the activated-sludge process is SRT.

PROCESS CONTROL

Dissolved Oxygen Control.

When oxygen limits the growth of microorganisms, filamentous organisms may predominate and the settleability and quality of the activated sludge may be poor. In general, the dissolved oxygen concentration in the aeration tank should be maintained at about 1.5 to 2 mg/L in all areas of the aeration tank.

• Wastewater normally contains soap, detergents, and other surfactants that produce foam when the wastewater is aerated.

• ( fig – Tapovan S.T.P. )

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