Application of filter media surface hydrophobic modification to reduce bioclogging in the infiltration system

Biological aerated filtration is a viable option for small municipal wastewater treatment plants. A low cost filter media was obtained by triturating volcanic rock. An apparent porosity of 46 % and a specific surface area of 395 m2/m3·d were obtained once the filter was packed by using a grain size of 8.2 mm. The performance of the system, operated as a biological filter, was evaluated under an average organic load of 2.6±0.4 kgCODT/m3·d (6.7±1.1 gCODT/m2·d) without primary and secondary settling. The average CODT decreased from 220 mg/l in the influent to 88 mg/l in the effluent and the CODD was decreased from 148 mg/l in the influent to 50 mg/l in the effluent. The filter media, in combination with the biofilm, allowed a 75 % TSS removal. The ammonia nitrogen decreased from 51 mg/l in the influent to 33 mg/l in the effluent. The maximum flux coefficients of 9.3gCODdissolved/m2·d and 2.9gNH4-N/m2·d at the biofilm surface were used to simulate, with the Michaelis-Menten model, the profiles of dissolved COD, ammonium and nitrates through the aerated filter. It was possible to conclude that the backwashing procedure removed the excess biomass and was responsible for a homogeneous distribution of heterotrophic and autotrophic microorganisms along the filter depth.

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Role of filter media in an anaerobic fixed-bed reactor

Water Science & Technology ◽

10.2166/wst.1995.0353 ◽

1995 ◽

Vol 31 (9) ◽

pp. 137-144 ◽

Cited By ~ 3

Author(s):

T. Miyahara ◽

M. Takano ◽

T. Noike

Keyword(s):

Anaerobic Bacteria ◽

Fixed Bed ◽

Methanogenic Bacteria ◽

The Other ◽

Fixed Bed Reactor ◽

Filter Media ◽

Fixed Bed Reactors ◽

Attached Bacteria ◽

The Relationship

The relationship between the filter media and the behaviour of anaerobic bacteria was studied using anaerobic fixed-bed reactors. At an HRT of 48 hours, the number of suspended acidogenic bacteria was higher than those attached to the filter media. On the other hand, the number of attached methanogenic bacteria was more than ten times as higher than that of suspended ones. The numbers of suspended and deposited acidogenic and methanogenic bacteria in the reactor operated at an HRT of 3 hours were almost the same as those in the reactor operated at an HRT of 48 hours. Accumulation of attached bacteria was promoted by decreasing the HRT of the reactor. The number of acidogenic bacteria in the reactor packed sparsely with the filter media was higher than that in the closely packed reactor. The number of methanogenic bacteria in the sparsely packed reactor was lower than that in the closely packed reactor.

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Pilot-plant experiments for improvement of polluted canal/klong water by rock-bed filtration

Water Science & Technology ◽

10.2166/wst.1997.0300 ◽

1997 ◽

Vol 35 (8) ◽

pp. 83-90

Author(s):

Shigeo Fujii ◽

Chiaki Niwa ◽

Mitsuo Mouri ◽

Ranjna Jindal

Keyword(s):

Organic Matter ◽

Pilot Plant ◽

Horizontal Flow ◽

Removal Mechanism ◽

Soluble Organic Matter ◽

Filter Media ◽

Canal Water ◽

Rock Bed ◽

One Year ◽

Filtration Technique

Applicability of the rock-bed filtration technique was investigated through pilot-plant experiments in Bangkok, Thailand. Polluted canal water was used as horizontal flow influent to two reactor channels filled with rocks. During one year operation, HRT, filter media, and aeration mode, were changed in several runs. The results showed that 1) the rock-bed filtration with aeration and the HRT more than 6 h can successfully improve polluted klong water by reducing the pollutants (e.g. 60-120mg/L of SS to 20-40 mg/L and 15-30 mg/L of BOD to 5-20 mg/L); 2) main removal mechanism seems to be the sedimentation resulting from the settleability enhanced by aeration, and the biofilm attached onto rocks also works in the reduction of soluble organic matter; 3) a combination of three rock sizes arranged in descending order showed best results; 4) longer HRT (13 h) produces better effluent but is not so effective if it exceeds 9 hours; 5) 60-70% of sediment IL was decomposed in a year, and porosity in rock beds reduced approximately 16%.

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