Trickling Filter, Wastewater Treatment method

Trickling Filter
A trickling filter is a type of wastewater treatment system.
• A trickling filter , also called trickling biofilter, biofilter, biological filter and biological trickling filter , is a fixed-bed, biological
reactor that operates under (mostly) aerobic conditions.

1. Trickling Filter
By DewakaPoudel
7
th
semester
Environmental Biotechnology
29/08/2022

2. Content:
Introduction, Principle
Design, Operation
Type, Advantage and Disadvantage
Conclusion

3. https://assignmentpoint.com/wp-content/uploads/2013/05/trickling-filters.jpg
Trickling Fillter

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d-Growth.jpg
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5. Introduction
•Atrickling filteris a type ofwastewater treatmentsystem.
•A trickling filter , also called trickling biofilter, biofilter, biological filter and biological trickling filter , is a fixed-bed, biological
reactorthat operates under (mostly) aerobic conditions.
•Trickling filters are conventional aerobic biological wastewater treatment units, such asactive sludge systemsorrotating biological
contactors.
•Trickling filters are a secondary treatment after a primary setting process (see alsoseptic tanksorpre treatment).
•Trickling filter process can define as the biological system, which tends to separate or degrade the maximum organic and inorganic
waste (up to 85%) out of the primary or raw sludge via the slime layer.

6. Principle:
•Pre-settled wastewater is continuously ‘trickled’ or sprayed over the filter. As the water migrates through the pores of the filter, organics
are aerobically degraded by the biofilm covering the filter material.
Schematic cross-section of a trickling filter. Source: TILLEY et al. (2014)

7. 1.Work Flow Diagram
2. Trickling filter
3.Flow pathway of Trickling Filter

8. BarRacks:A rough screening device, eith
er vertical or inclined, with parallel bars s
paced 3 inches apart, placed in a wastew
ater collection pipe or other waterway to
catch debris. The screenings may be raked
from it.

9. Operation:
The trickling filter process goes through a series of operation, which involves the following stages:

10. 1.Filterbed: It is a bed chiefly containing crushed rock or other coarse media.
The construction of a filter bed is roughly 6 feet deep and 200 feet in thickness.
Settled sewage isflushed evenlyover the filter bed containing organic and
inorganic waste via continuously rotating distributor’s arm. Holes within the
rotary distributor arm facilitates the trickling of primary influent and settled
sewage throughout the filter bed.
2.Microbialfilm: Within the filter media some aerobic microbes are found on the
surface, and some anaerobic microorganisms are found below the filter media.
As the wastewater trickles downward, the microorganisms associated with the
filter media starts utilizing theorganicmatterof the wastewater and forms a
later calledmicrobialslime. Thus, the microorganisms in the filter media play a
pivotal role in degrading the organic matter in the sewage, thereby minimizes
BOD and COD from the sewage.

11. Drainage system: The treated wastewater from the trickling filter bed
goes down the drainage system and further undergoestertiary
treatmentvia membrane filter and disinfection before secondary
sedimentation. Asecondaryclarifieris a sedimentation unit, which
separates the small colloids, suspended particles etc. at the bottom out
of waste fluid.
Besides, the tertiary treatment is also necessary for the safe disposal of
the effluent, as this step eliminates the pathogenic microorganisms. In
contrast, the oxidized or decomposed organic matter sloughed down
and recycled back in the trickling filter mediated via return pump.

12. Types of Trickling Filters:
Depending upon the hydraulic and organic shock load, trickling filters can be categorized into two types,
namelyhigh rateandStandard rate trickling filter. The hydraulic loading rate can define as the sewa
ge flow (Q) per unit volume (V) of filter bed in a day, while the organic loading rate can define as the kil
ograms of BOD (Y
5) introduced into the per unit volume (V) in a day.
1.TheBOD removal efficiencyof both standard and high rate trickling filter is about 75 to 90%. The nitrif
ication of the primary effluent is relatively higher in standard rate filters, whereas high rate trickling filters
produce partially nitrified effluent.
2.Standard rate and high rate trickling filter are suitable for the treatment of low to high strength domestic
wastewaters and industrial wastewater.
Recirculationof the effluent is not provided in the Standard rate filters. In contrast, high rate filters are
provided with return pump between the trickling filter tank and secondary clarifier that aids in efflu
ent recirculation.
To identify the characteristic difference between the two, one can look upon the table given below t
hat specifies the efficiency and depth of the standardandhigh rate trickling filter. Recirculationratio
is recirculation discharge upon incoming discharge.

13. Properties
Standardrate trickling
filter (SRTF)
High rate trickling
filter(HRTF)
Hydraulic loading 1-4 m3/m2.d 10-40 m3/m2.d
Organic loading 0.08-0.32 kg BOD/m3.d0.32-1.0 kg BOD/m3.d
Depth 1.8-3.0 m 0.9-2.5 m
Recirculation ratio 0 0.5-3.0-domestic
wastewater
8-strong industrial
wastewater

14. Advantage and Disadvantage:
Advantages:
1.Can be operated at a range of organic and hydraulic loading rates
2.High effluent quality in terms of BOD and suspended solids removal; in com
bination with a primary and tertiary treatment also in terms of pathogens
3.It is a simpleand reliable secondary treatment unit of the wastewater.
4.It can be used to degradea variety of organic waste.
5.Trickling filter can resistshock loadings.
6.It efficiently oxidizesthe ammonia or efficient in ammonium oxidation.
7.Trickling filter aids to produce effluentfreeof BOD, COD, nutrients, suspend
ed colloids etc.
8.Its constructionrequires a small land area, unlike constructed wetland.
Disadvantages:
1.Its designing requires highcapital costs.
2.The designing of a trickling filter requires expertskills.
3.Its operation and maintenance require regularattention by the skilled
labourpersonnel.
4.The trickling filter process is a continuousprocess, which needs an
uninterruptedsupply of electricity and wastewater distribution.
5.It sometimes causesflies breeding and odourproblem.
6.The effluent produced by the trickling filter needs to treated furtherby
the chemical disinfectants.
7.Accumulationof excessive biomass may cause clogging of the TF-unit.
8.Notall parts and materials may be locally available.

15. Conclusion:
Therefore, we can conclude that the trickling filter process is one of theattached growth system, which means that the microorgani
sms responsible for the degradation of the organic matter are attached to thenon-submergedpacking material. It is designed forth
e secondary treatment of the primary influent to eliminate the suspended and soluble organic waste along with the nutrients.
https://www.netsolwater.com/netsol-water/assets/img/product-images/How-to
-design-trickling-filters-and-Size-and-capacity.png

16. References:
1.^Jump up to:
abc
"Biological wastewater treatment processes; secondary treatment". Staffordshire University.
Archived fromthe originalon 18 April 2011. Retrieved13 December2019.
2.^"Updates on the wastewater treatment plant stench". Christchurch City Council. Retrieved13 June2022.
3.^Saudi Aramco."Saudi Aramco Engineering Development Program"(PPT). King Fahd University of Petroleum and
Minerals. pp.62–65. Archived fromthe original(PPT)on 2011-07-28.
4.^US patent 4351729, Enrique R. Witt, "Biological filter and process", issued September 28, 1982
5.^Davis, Allen."Recirculating Systems"(PDF).Auburn University. p.6. Archived fromthe original(PDF)on October
23, 2015.
6.^Beychok, Milton R. (1967).Aqueous Wastes from Petroleum and Petrochemical Plants(1sted.). John Wiley &
Sons Ltd.LCCN67019834.
7.^Bryan, E.H.; Moeller, D.H. (April 20, 1960).Aerobic Biological Oxidation Using Dowpac. Conference on Biological
Waste Treatment. Manhattan College.
8.^Van Sperling, Marcus (2007).Activated Sludge and Aerobic Biofilm Reactors. IWA Publications.ISBN978-1-
84339-165-4.
9.https://biologyreader.com/trickling-filter-process.html

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