This document discusses different types of trickling filters classified by organic and hydraulic loadings or by the number of units used in series. Trickling filters are classified as low rate, high rate, intermediate rate, or roughing filters depending on loadings. They can also be single stage or double stage depending on the number of units used. Low rate trickling filters typically produce consistent effluent quality with varying influent. High rate trickling filters use recirculation to increase hydraulic loading and improve sloughing. Roughing filters are high rate filters that require low energy for treating high strength wastewater.

1. Presentation onTypes of
Trickling filters
By:Muttu j Hugar
1MS14CV072
M S raMaIaH INStItutE OF
tECCHONOLOgy

2. Types of Trickling Filters
They are classified based on
1)According to Organic & Hydraulic loadings
2)According to the number of units used in series
1)According to Organic & Hydraulic loadings
1)Low rate trickling filters
2)High rate trickling filters
3)Intermediate rate trickling filters
4)roughing trickling filters
2)According to the number of units used in series
1)Single stage trickling filters
2)Double stage trickling filters

3. Low rate trickling filters (LRTF)
➢
These relatively simple treatment units that normally
produce a consistent effluent quality even with
varying influent strength.
➢
They are generally not provided with recirculation of
effluent.
➢
Depending upon the dosing system, wastewater is
applied intermittently
➢
With proper loadings the LRTF, including primary
and secondary sedimentation units, should remove
from 80 to 85 percent of the applied BOD.

4. High Rate Trickling Filters (HRTF)
●
When recirculation is used, the hydraulic loading
per unit area of filter media is increased.
●
As a result, higher flow velocities will usually occur
causing a more continuous and uniform sloughing
of excess growths.
●
High-rate trickling filters, including primary and
secondary sedimentation, should, under normal
operation, remove from 65 to 85 percent of the
BOD of the wastewater.

5.  Roughing Filter
●
Roughing filters are high rate type filters
designed with plastic packing.
●
In most cases roughing filters are used to
treat wastewater prior to secondary
treatment.
●
low energy is required for BOD removal of
high strength wastewaters as compared to
activated sludge process because the
energy required is only for pumping the
influent wastewater and recirculation flows

7. Single stage trickling filter
●
Here only single filter is adopted
●
When two or more filters are required
they will provide in parallel
●
Generally recirculation is not provided

8. Single stage filter with recirculation

9. 2)Double stage trickling filter
●
This system consist of two filters in
series
●
Here re-circulation of effluent is
normally adopted

10. Two-stage filter with recirculation

11.  Advantages
The effluent obtain is highly nitrified and stabilised
They can remove about 80% of suspended solids and about 80%
BOD
The rate of loading is in comparison with contact bed process
It is simple, cheap and does not required any skilled supervision
They are self cleansing
Mechanical wear ant tear is less as it contain less mechanical
equipments
It require less electricity power to run mechanical equipment
The moisture content of sludge obtained from this is as high as
99%

12. Disadvantages
 High capital costs
The loss of head through the filter system
is high thus making the automatic dosing
It requires large area
Final settlement in humus tank necessary
This process may develop odur and fly
nuisance

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