Civil - Environmental Engineering - Sewage Treatment
Important Question And Answer: Primary Treatment Of Sewage
1.Define humus tank?
The efficient of the filter is therefore, passed through a sedimentation take called Humus tank otherwise called secondary clarifier or secondary setting take.
2.What are the distinct stages in the sludge digestion processes?
· Acid fermentation
· Acid repression
· Alkaline fermentation
3.Define the term ripened sludge?
This digested sludge is collected at the bottom of the digestion tank and is also called repented sludge.
4. What are the factors effecting sludge digestion?
· Pit value
· Seeding wotu digested sludge
· Mixing and stirring of the raw sludge with digested sludge.
5.What are functions of aeration in ASP?
· Oxygenation of the mixed log wor
· Flocculation of the colloid in sewage influent
· Suspension of activated sludge
6.What are the methods employed for the purpose of certain in ASP?
· Diffused air aeration air aeration
· Mechanical aeration
· Combined diff used air and Mechanical aeration
7.What are the patterns of mechanical aeration?
· Haworth paddle or Sheffield aeration system
· Hartley paddle or bir Mangham Bio flocure lation system
· Simplex aeration system
· Link belt aeration system
· Kessner Brush aeration system
8.List out the important aeration processes in the ASP?
· Conventional process
· Tapered aeration process
· Step aeration process
· Contact slabolisection process
· Completely mixed process
· Modified aeration
· Extended aeration
9.What are the advantage of stabilization ponds or cagoins
· Lower initial lost than required for a mechanical plant.
· Tower operation costs
· Regulation of efficient discharge possible their provoelving control of pollection during critical times of the year.
10.What are the disadvantage of tagoons?
· Requires extensive land area.
· Hence the method can be used only on rural area.
· If used in urban areas, expansion of town and new developments may encroach on the lagoon site.
11.What do you understand by facultative ponds?
A facultative panel combine the features of the acrobite and anacrobic ponds.
· Constructed of intermediate depta (1, to 1.5m)
· A facilitative bond consists of three
ü Aaerobic Zone
ü Faculative zone
ü Anacrobic zone
12.What are remedial measurement for rising sludge problem?
· Increasing the return sludge age
· Increasing the speed of the sludge scroper mechanism, where possible
· Decreasing the mech cell residence come by increasing the sludge write rate
13.What is meant by sludge bulking?
Sludge with poor setting characteristics is termed bulking sludge. It
results on poor influent due to thee presence of excessive suspended solids and also in rapid loss of MISS from aeration tank.
· The efficient from intermittent sand filter is of better quality. It is more clean and more stable and hence does not need further treatment before disposal
· The filter work under acrobic conditions, and hence there is no trouble of odour, files and inserts
· The operation is very simple, requiring no mechanical equipment except for dosing
15.What are the disadvantages of intermittent sand filters?
· The rate of filtration and hence that of load long is very small per unit surface area of the filter hence they cannot be employed for medium size or bigger plants
· They requires large area and large quantity of sand due to which their construction is very lostly.
16.What do you understand by contact beds?
· Confact beds, also called confact filters, are similar to inter mitten sand filters in construction, except that th filtering media is very coarse, consisting of broken stones called ballart of 20 to 50mm gauge.
· A contact bed is a water trough take of masonry walls and of rectangular shape.
· The depth of filtering media is kept b/w 1 to 1.8m
17.What are the operations involved in the contact beds?
work under small heads.
· Contact beds can be operated without exposing the sewage efficient to view.
· There is no nuisance of filter flows
· The problem of odour is much less as compared to trill long filters.
19.What are the disadvantage of contact beds in T.F?
· Rate of loading is mech less in comparison to trilling filters.
· Large areas of land is required for their installation
· intermittent operation requires continceoces attendance
· The cost of contact beds is mech more as compared to trick long filters
19.What do you mean by tracking filters?
Tricking filters, also as percolating filters or sprinkling filters or sprinkling filters are similar to contact beds in construction, but their operation is confinceous and they allow constant aeration In this system sewage is allowed to sprinkle or trickle over a bed of coarse, rough hard filter media and it is then collected through the under drainage system
20.What are the purpose of under drainage system?
The purpose of under drainage system is two fold
· To carry away the liquid efficient and sloughed biological solids.
· To distribute air through the bed
· The efficient obtained from truckling filters is highly nitrified and stabilized. The efficient can there fore be disposed of in smaller quantity of deputation water
· It has good dependability to produce good efficient under very widely varying whether and other conditions
· The working of truckling filter is simple and sheep and does not require any skilled supervision
22.What are the demerits of conventional trickling filters?
· The loss of head through the filter system is high their making the automatic dosing through siphonic doing tank necessary.
· The cost of construction of the filter is high .
· They require large area in comparison to their biological treatment processes.
23.What is the necessary of Recirculation in T.F?
Recirculation is necessary to provide uniform hydraulic loading as well as to dilute the high strength waste waters. In constant to the low rate filters, in high rate filters a part of settled or filter efficient is recycled through the filter.