User-friendly and low-cost wastewater treatment plants are good options for treating wastewater of small communities. The effluent of these treatment plants can be improved by various methods including using a horizontal rouphing filter (HRF). In this paper, HRF performance was evaluat by passing the Parkandabad wastewater treatment plant effluent through pilot scale constructed HRF. The HRF was constudted with fourcompartments of different sand sizes and was operated under three filtration rates of 0. 5, 1 and 1. 5 m3/m2. h. The results obtained from this study showed that the HFR performed the best at filtration rate of 0. 5m/h when the removal efficiency for BOD5 and COD was 61 and 63 %, respectively. Optimum removal efficieny of BOD5 and COD up to 65% could be achieved with an extended filtration run length. However, longer duration of filter operation after 4 months, reduced the filter performance for BOD5 and COD removal efficiency to 56. 8 and 61. 5%, respectivel. In conclusion, by using 4-compartment HRFs, compared with the conventional 3-compartment filtration, it may be possible to produce effluent quality for BOD5 and COD that is permissible for agricultural irrigation purposes.

Background and Objectives: Horizontal roughing filters (HRF) can properly remove suspended solids and microorganisms from surface water resources especially on filtration rates less than 1.5 m/h. This research was aimed at suspended solid removal efficiency of HRF during secondary wastewater effluent filtration. Methods: This experimental study was conducted by installing an HRF pilot system on effluent pumping station of Qom wastewater treatment plant based on aerated lagoon process. The pilot was a horizontal cylindrical column consisting of three compartments filled with river gravels in various sizes. Grab samples were simultaneously taken from HRF inlet and outlet in three filtration rates: 0.5 1 and 1.5m/h Results: The results indicated that filtration rate had a significant effect on the amount of total suspended solids in HRF effluent. During optimum operation of HRF removal efficiencies of three filtration rates (0.5 1 and 1.5 m/h) were 78.5 63.1 and 66.9 respectively. Conclusion: T-test analysis indicated that with a significance difference outlet effluent from HRF in all three flow rates met the standard requirements of Iran Environmental Protection Agency for irrigation and discharge to surface water.

Horizontal roughing filters (HRF) can properly remove suspended solids and microorganisms from surface waters if they operate at filtration rates below 1.5 m/h. These filters are common raw water pre-treatment before slow sand filters. This study was conducted by installing an HRF pilot system on effluent pumping station city of Qom wastewater treatment plant based on the aerated lagoon process. The pilot was a horizontal cylindrical column consisting of three compartments filled with river gravel of various sizes. Grab samples were simultaneously taken from inlet and outlet of the HRF at three filtration rates: 0.5, 1, and 1.5 m/h. Total and fecal coliforms were tested according to standard methods for water and wastewater tests. Results indicated that filtration rate had a significant effect on the amounts of total and fecal coliforms in HRF effluent. For the HRF steady-state operation, average total coliform removal efficiency for all filtration rates was higher than 87 percent.

Slow Sand Filters are as a proper technology for pre-treatment of raw water, with a fine and medium trubidity in small communities in developing countries. Thus, with a minimum operation cost and minimum need for expest bodies have the maximum efficiency. The purpose of this research is carried out to evaluate the efficiency of two processes of horizontal flow roughing filter and vertical flow roughing filter, in order to remove the trubidity and parasite egg from water. For this purpose, two series of pilots are used, each pilot has 3 sections, which consists of granular particles of 4-25 mm. First section of each filter is filed with the granuls of 12-18 mm in diameters. Second section of each filter also contains with sand of 8-12 mm in diameters and the third section of each filter also contains with the sand of 4-8 mm in diameters. The head sections 1, 2 and 3 were 1 meter in down flow roughing filter, respectively. Samples of turbid water, which were made artificially (silty soil + water) and sample waters with different turbidities were injected into two systems and since on of the other goals of research was to study the efficiency of these filters, in removal of parasitic egg from water, therefore from the total concentrates which were prepared from parasitic eggs; such as:Ascaris, Fasicola hepatica and Trichosephal and water was added to them. These samples were finally passed through filters. The outcomes of the study, indicate that accelerating the filteration process, leads to declined efficiency of both filters. Horizontal flow roughing filters also have a higher efficiency compared with medium and fine media filters, in removing trubidities, in such manner that these filters are able to treat and refine waters with turbidities of 500-1000 NTU which vertical flow roughing filters, are only able to receive waters with turbidities up to 150 NTU.

Background: The need to improve the quality of lagoon effluent is one of the environmental priorities for wastewater projects. Thus, the study objective was to investigate horizontal roughing filter (HRF) performance in reducing total suspended solides (TSS), chemical oxygen demand (COD), turbidity and fecal coliform in the effluent from polishing pond following aerated lagoons in order to comply with the national effluent standards.Methods: A pilot-scale experimental study was carried out on-site in the wastewater treatment plant of Boukan, Iran. Design, manufacture and installation of horizontal roughing filter pilot were performed according to Wegelin guidelines. HRF Performance for the removal of TSS, COD, turbidity and fecal coliform was studied in three filtration rates of 0.5, 1 and 1.5 m3/m2.hr. The results were analyzed by analysis of covariance (ANCOVA) using SPSS software, V.16.Findings: The mean TSS, COD, turbidity and fecal coliform in the horizontal roughing filter effluent had significant difference within various hydroulic loading rates (P<0.001). Accordingly, in hydroulic loading rate of 0.5 m3/m2.hr as optimum loading rate, the HRF reduced TSS, COD and turbidity of effluent from the polishing pond following aerated lagoons to 21 mg/L, 35 mg/L and 8.33 NTU, respectively.Conclusion: The HRF can be used as appropriate option, due to high efficiency and easy operation, to improve the quality of effluent from the polishing pond following aerated lagoons in order to reach the national discharge standards.

The creation of very pollute palm oil mill waste water has resulted in semiserious environmental hazards. The reason for the current study is to test the optimal removal of ammonia nitrogen (NH3-N) from palm oil mill waste water by filtration using inexpensive filters media in place of current methods, to remove ammonia nitrogen from palm oil mill effluent. A series of batch and column studies were conducted using a different particle size of limestone (4, 12 and 20 mm) at various filtration rates of 20 ml/min, 60 ml/min and 100 ml/min. An experimental model design was conducted using Central Composite Design (CCD) in Response Surface Methodology (RSM). RSM was used to calculate the outcomes of process variables and their role in reaching ideal conditions. Equilibrium isotherms in this study were evaluated using the Langmuir and Freundlich isotherm. Using statistical analysis, the NH3–N removal model proved to be very significant with very low probability values (0.0001). The column study showed that ideal NH3-N removal was attained using a lower flow rate and smaller sized limestone (LS). The ideal conditions found when using 4 mm limestone and a 20 ml/min flow rate. This resulted in 45.3% removal of NH3–N which was seen in the predicted model, and fit well with the laboratory results (45%). The adsorption isotherm data fit the Langmuir isotherm.

This study aimed at the examination of the efficiency of a roughing filter in nitrate and Chemical Oxygen Demand (COD) removal from fresh leachate from a municipal solid waste landfill. Sampling was done at three rates of 0. 5 m/h, 1 m/h, and 1. 5 m/h from input and output of the filter to determine the concentration of nitrate and COD. The average efficiencies of COD removal at filtration rates of 0. 5 m/h, 1 m/h, and 1. 5 m/h were 84, 88, and 85%, respectively. The average removal efficiencies of nitrate at filtration rates of 0. 5 m/h, 1 m/h, and 1. 5 m/h were 88, 88, and 85%, respectively. The effluent concentrations of COD and nitrate were lower than the environmental protection agency standard values (P<0. 05). Based on the results, nitrate removal with a roughing filter was better than COD removal.

Vertical or horizontal flow gravel beds can be used in water treatment as roughing filters. In order to improve the performance of horizontal flow roughing filtration (HRF) this process has been modified earlier by applying a constant coagulant dose prior to filtration named direct horizontal roughing filtration (DHRF). In this research a lab scale DHRF pilot plant was used for investigate DHRF performance. The study results indicated that DHRF (6.5 m long consisting of 2.5 m first compartment with 12-18 mm diameter grain, 2 m/s compartment with 8-12 mm diameter and 1.5m third compartment with 4-8 mm diameter) was systematically yielded good effluent quality (<2NTU, C.I=0.95) with raw water quality of 200-400 NTU. DHRF is a versatile pretreatment process capable of handling wide fluctuation in raw water turbidity (200-400 NTU) while operating condition such as coagulant dose [2mg Fe (III)/L], mixing intensity, time and filtration rate remained unchangeable.