Pilot plant study of alternative filter media for rapid gravity filtration

2012 ◽  
Vol 66 (12) ◽  
pp. 2779-2784 ◽  
Author(s):  
P. D. Davies ◽  
A. D. Wheatley

Sand has been the main filter media used in rapid gravity filtration since its introduction. The dominance of sand has been due to its low cost and availability. Extensive experience has led to sand filters with a dependable and predictable performance. Sand remains the preferred filter medium but usually with a larger sized anthracite capping to reduce the onset of head loss. Other approved filter media are now commercially available and this paper compares sand with recycled glass, Filtralite® and slate at pilot scale. The results have reaffirmed the basic importance of particle size on head loss and turbidity performance rather than surface activity or specific surface area. The results did suggest, however, that particle shape and packing exerted a stronger influence on performance than previously acknowledged. These could be used to improve the design and the contribution to sustainability made by rapid gravity filters.

2002 ◽  
Vol 2 (2) ◽  
pp. 107-113 ◽  
Author(s):  
J. Wang ◽  
P. Deevanhxay ◽  
T. Hasegawa ◽  
Y. Ehara ◽  
M. Kurokawa ◽  
...  

A new inorganic polymer coagulant of polysilicato-iron (PSI) was evaluated as an alternative to aluminium coagulant. In this study, long-term performance of PSI on coagulation, sedimentation and filtration for phytoplankton, turbidity and DOC in raw water from a eutrophic reservoir were evaluated by a pilot plant in comparison with PAC. PSI was found to be more effective in the coagulation and removal in comparison with PAC. The flocs formed by PSI could be settled more quickly than those by PAC and, therefore, the size of sedimentation facilities can be reduced by the introduction of PSI. PSI was able to produce filtered water with low turbidity and colour. The number of phytoplankton cells in the filtered water of PSI was smaller than that of PAC. Most of the residual flocs in the settled water were trapped in the coarse layer of anthracite, and this result suggested that a higher rate of filtration can be achieved with PSI by increasing particle size of the filter media.


2019 ◽  
Vol 79 (4) ◽  
pp. 771-778 ◽  
Author(s):  
Junho Lee ◽  
Myungjin Lee

Abstract This study has been carried out to evaluate the applicability of the pilot scale hybrid type of stormwater runoff treatment system for treatment of combined sewer overflow. Also, to determine the optimum operation parameter such as coagulation dosage concentration, effectiveness of coagulant usage, surface loading rate and backwashing conditions. The pilot scale stormwater filtration system (SFS) was installed at the municipal wastewater plant serving the city of Cheongju (CWTP), Korea. CWTP has a capacity of 280,000 m3/day. The SFS consists of a hydrocyclone coagulation/flocculation with polyaluminium chloride silicate (PACS) and an upflow filter to treat combined sewer overflows. There are two modes (without PACS use and with PACS use) of operation for the SFS. In case of no coagulant use, the range of suspended solids (SS) and turbidity removal efficiency were 72.0–86.6% (mean 80.0%) and 30.9–71.1% (mean 49.3%), respectively. And, the recovery rate of filter was 79.2–83.6% (mean 81.2%); the rate of remaining solid loading in filter media was 16.4–20.8% (mean 18.8%) after backwashing. The influent turbidity, SS concentrations were 59.0–90.7 NTU (mean 72.0 NTU), 194.0–320.0mg/L (mean 246.7mg/L), respectively. The range of PACS dosage concentration was 6.0–7.1mg/L (mean 6.7mg/L). The range of SS and turbidity removal efficiency was 84.9–98.2 (mean 91.4%) and 70.7–96.3 (mean 84.0%), respectively. It was found that removal efficiency was enhanced with PACS dosage. The recovery rate of filter was 92.0–92.5% (mean 92.3%) the rate of remaining solid loading in filter media was 6.1–8.2% (mean 7.2%) after backwashing. In the case of coagulant use, the particle size of the effluent is bigger than influent particle size. The results showed that SFS with PACS use more effective than without PACS use in SS and turbidity removal efficiency and recovery rate of filter.


2021 ◽  
Vol 43 (3) ◽  
pp. 146-159
Author(s):  
Junho Lee ◽  
Daesik Song

Objectives : The objective of this study is to investigate the performance of the fiber-ball media upflow filtration system for non-point pollutants treatment.Methods : The additional air backwashing nozzle were installed between upper and lower fliter media cartridge. The effect of feed SS concentration, surface overflow rate, retention time, head loss on the removal efficiency were investigated respectively. Particle size distribution, SEM, and backwashing effect were also analyzed.Results and Discussion : The operated of upflow filter mean retention time, mean head loss were 1.99 min, 7.2 cm. On condition of SOR 480 m3/m2/day, results indicate that the range of removal efficiency of turbidity and SS were 76.8 ~ 93.21% (mean 88.3%) and 85.4 ~ 97.9% (mean 92.7%), respectively. The effluent turbidity and SS were under 15 NTU, 20 mg/L, respectively.Conclusions : Since turbidity can be continuously monitored in a filtration non-point pollution treatment system, turbidity can be used as a operation factor in evaluating operating conditions. The particle size the effluent larger than the influent was due to bonding, collision and adsorption between particles in the pores of the filter media. SEM analysis showed that after backwashing, very fine particles in the filter medium were not removed but adhered to the fiber yarn and remained. The average recovery rate of fiber-ball media filtration was 88.7%, which is evaluated as excellent in backwashing.


2012 ◽  
Vol 5 (1) ◽  
pp. 73-85 ◽  
Author(s):  
L. D. Sánchez ◽  
L. M. Marin ◽  
J. T. Visscher ◽  
L. C. Rietveld

Abstract. This paper assesses the operational and design aspects of coagulation and flocculation in upflow gravel filters (CF-UGF) in a multi-stage filtration (MSF) plant. This study shows that CF-UGF units improve the performance of MSF considerably, when the system operates with turbidity above 30 NTU. It strongly reduces the load of particulate material before the water enters in the slow sand filters (SSF) and therewith avoids short filter runs and prevents early interruption in SSF operations. The removal efficiency of turbidity in the CF-UGF with coagulant was between 85 and 96%, whereas the average efficiency without coagulant dosing was 46% (range: 21–76%). Operating with coagulant also improves the removal efficiency for total coliforms, E-coli and HPC. No reduction was observed in the microbial activity of the SSF, no obstruction of the SSF bed was demonstrated and SSF runs were maintained between 50 and 70 days for a maximum head loss of 0.70 m. The most important advantage is the flexibility of the system to operate with and without coagulant according to the influent turbidity. It was only necessary for 20% of the time to operate with the coagulant. The CF-UGF unit represented 7% of total construction costs and the O&M cost for the use of coagulant represented only 0.3%.


Author(s):  
Bruno Moreno Ramos da Silva ◽  
Rafael Kopschitz Xavier Bastos ◽  
Pedro Kopschitz Xavier Bastos

Abstract The objective of this work was to evaluate the crushed rock sand (CRS) as a filter bed in rapid filtration for water treatment. The experiments were carried out using pilot-scale filtration units: one with a CRS filter bed and the other with natural river sand (NRS). Both filter media were prepared in accordance with typical standards for rapid sand filtration (particle size range and distribution, and filter bed depth), and were further characterized in terms of chemical composition, particles and bulk density, porosity, acid solubility and sphericity coefficient. Over four months, 14 filter runs using filtration rates of 90, 180, 270 and 360 m3 m−2 d−1 were monitored and characterized in terms of run length, head loss increase along filter bed depth, turbidity removal along filter bed depth. Overall, the performance of the CRS filter was similar to or even better than that of the NRS filter, producing filtered water with turbidity lower than 0.50 NTU along the entire run, with head loss increasing rates and run length similar to those of the NRS filter. It is concluded that CRS presents a high potential for use as filter media for rapid filtration in water treatment, without technical or operational disadvantages.


2012 ◽  
Vol 5 (1) ◽  
pp. 291-332 ◽  
Author(s):  
L. D. Sánchez ◽  
L. M. Marin ◽  
J. T. Visscher ◽  
L. C. Rietveld

Abstract. This paper assesses the operational and design aspects of coagulation and flocculation in upflow gravel filters (CF-UGF) in a multi-stage filtration (MSF) plant. This study shows that CF-UGF units improve the performance of MSF considerably, when the system operates with turbidity above 30 NTU. It strongly reduces the load of particulate material before the water enters in the slow sand filters (SSF) and therewith avoids short filter runs and prevents early interruption in SSF operations. The removal efficiency of turbidity in the CF-UGF with coagulant was between 85 and 96%, whereas the average efficiency without coagulant dosing was 46% (range: 21–76%). Operating with coagulant also improves the removal efficiency for total coliforms, E-coli and HPC. No reduction was observed in the microbial activity of the SSF, no obstruction of the SSF bed was demonstrated and SSF runs were maintained between 50 and 70 days for a maximum head loss of 0.70 m. The most important advantage is the flexibility of the system to operate with and without coagulant according to the influent turbidity. It was only necessary for 20% of the time to operate with the coagulant. The CF-UGF unit represented 7% of total construction costs and the O&M cost for the use of coagulant represented only 0.3%.


2002 ◽  
Vol 46 (9) ◽  
pp. 171-177 ◽  
Author(s):  
E. Yüksel ◽  
Ö Akgiray ◽  
A.M. Saatçi ◽  
H.Z. Sarikaya ◽  
I. Koyuncu

Two identical pilot scale sand filters were operated in parallel to study the effects of preozonation in direct filtration. No coagulants were used. The influent of one filter was ozonated, whereas the influent to the second filter was aerated. Significantly improved reduction in turbidity, particle count, and iron was observed with the filter receiving preozonated water. The head loss development rate was increased as a result of using ozone. In a second set of experiments, the effects of ozone injection point on filter performance were investigated. Two identical filters both receiving preozonated water were operated. With one of the filters, the raw water was ozonated immediately before it entered the filter. The entrance of the preozonated water to the other filter was delayed by using a detention tank between the ozone contact chamber and the filter. In addition to effluent turbidity and particle count values, zeta potentials of the waters entering the two filters were measured. Head loss development at several locations within each filter bed was also observed and recorded. Slightly better effluent quality (turbidity and particle count) was observed with the filter receiving preozonated water without delay. It was observed that the zeta potential of the prezonated water became more negative with increasing delay time.


2008 ◽  
Vol 3 (3) ◽  
Author(s):  
O. González-Barceló ◽  
S. González-Martínez

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.


1993 ◽  
Vol 27 (5-6) ◽  
pp. 381-390 ◽  
Author(s):  
John Upton

The European waste water industry will need to develop denitrification processes to remove nitrogen as pressures increase to reduce nutrient levels discharged in effluents. In the USA deep bed filter technology has been used extensively to provide denitrification to levels less than 5 mg/l TN. This paper describes this technology and the full scale performance at some waste water plants in Florida, USA. This paper also describes a pilot study in the United Kingdom at Severn Trent Water. The results of the pilot plant study indicate that denitrification in deep bed sand filters is a sound robust technology using methanol addition. Nitrogen removals greater than the 70% required in the EC Directive 1991 are possible at winter sewage temperatures. The process is most suitable for achieving nitrogen removal at trickling filter plants. The cost of methanol addition is calculated to be ₤10/1000m3.


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