Bakery plants generates huge amount of waste water which are treated and then discharged into municipal drains or central treatment plants .As bakeries does not have heavy metal as its inputs hence waste water contains only bio degradable waste .Waste water is generated in bakeries by cleaning of factory floor , machinery and equipments , hoppers ,utensils and tray wash .This waste water contains flour dust , sugar , vegetable oil , milk ,chemicals which makes this water highly acidic in nature . This Effluent water cannot be discharged in open drains as per the standards stipulated by local /federal govt . Different countries have different values for treated water .Following characteristics are monitored such aspH , COD , BOD , TSS , TDS , Fat &Oil , Heavy Metals.Normally treated water values required would be in between these values
- pH - 6-10
- TSS = 1500 mg or less
- TDS = 2000mg or less
- BOD = 1000mg or less
- COD = 3000mg or less
- Oil&Grease = 100 mg or less
- Heavy metals = 1mg or less
To treat waste water in bakeries different types of effluent treatments methods are used .Following are most used methods for waste water treatment in bakeries .
- Aerobic - Air is mixed with the waste water through blower for aeration depending upon the volume.
- Anaerobic - Air is avoided and the water is maintained in closed tank and anaerobic ( bio culture ) reaction takes place . Methane gas is generated in such reaction which can be used for heating application .
- Combination aerobic and anaerobic method: Both aerobic and anaerobic tanks are used for waste water treatment . Waste water is first passed on to anaerobic tanks here major BOD reduction is done balance reduction is done in aerobic tanks .
Waste water treatment process
Waste Water are collected in collection pits .Waste water is then transferred to oil and grease traps here oil and grease are removed and then this water is transferred to equalisation tanks ,pH correction is done here at equalisation with addition of soda flakes from here water is transferred to aeration tanks where water is subjected to pressurised through root blowers after aeration water moves to clarifiers . In Clarifiers sludge is separated from waste water and transferred to final tank with filters in between which clears water from any flocculation or impurities . This treated water is either disposed of into open drains or are loaded to tankers which then decant this water into central effluent plants of the city . Sludge are spread on drying beds and are disposed off when it becomes dry .
This treated waste water can be recycled and used in agriculture , gardening , road construction , cooling tower , wash rooms .
