DEEP BED COLUMN DESIGN USING BURNT OIL PALM SHELL IN URBAN STORMWATER FILTRATION. Universiti Malaysia Sabah, Kota Kinabalu, Sabah.

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1 DEEP BED COLUMN DESIGN USING BURNT OIL PALM SHELL IN URBAN STORMWATER FILTRATION Nurmin Bolong 1, 2*, S. P. Lee 1, Rosdianah Ramli 1, 2 & Z.S. Tang 1, 2 1 Nano Engineering and Materials Research Group (NEMs), School of Engineering and IT, Universiti Malaysia Sabah, Kota Kinabalu, Sabah. 2 Civil Engineering Programme, School of Engineering and IT, Universiti Malaysia Sabah, Kota Kinabalu, Sabah. ABSTRACT. The study utilize burnt oil palm shell (BOPS) and river sand (RS) as filter media in a deep bed column design for stormwater filtration. Combination design of burnt oil palm shell (BOPS) and river sand (RS) were tested to obtain the removal of total suspended solid and turbidity, focusing at 150 mg/l of total suspended solid (TSS) and >50 turbidity which are determined via similar range based on on-site sampling at Sepanggar resident area of Kota Kinabalu stormwater. This value is classified as Class III in Interim National Water Quality Standard (INWQS) as a measure to evaluate the performance and reduce variation of filtration on the laboratory condition. Two groups of both BOPS and river sand media at coarse (range of 1 mm-2.5 mm) and fine ( mm) filter media were also further explored to compare the efficiency based on the fineness of the filter media. The deep bed column with finer filter media with combination media design has shown to have a better result in removal of suspended solid. The filtration results indicate that the optimum of 41% TSS and 35% turbidity removal occurs at mix ratio of 50% BOPS and 50% RS deep filter column design. KEYWORDS. Deep bed column, urban stormwater filtration, burnt oil palm shell (BOPS) filtration, dual media filtration INTRODUCTION River Sand (RS) is a conventional filter media whereas Burnt Oil Palm Shell (BOPS) is new and rare as filter media in Malaysia. BOPS has a tighter, higher resistance to abrasion, lower in and and more microporous pore structure which lead to application as filter media in water treatment (Siemens Water Technology, 2011). Deep bed filter is an equipment with particulate media beds to remove dirt and other solid contaminant from water (Salava & Douglas, 2010). In 1990s, a related study by Rahman (1992), walnut granules were used as deep bed filter media. The study showed that walnut shell granules are excellent coalescing material and have high absorption properties. Later, Jusoh et al (1995) utilized BOPS in rapid deep filtration. It was reported that size of BOPS filter media less than 2 mm could produce effluent turbidity of less than 1 NTU. Recently, investigation of Ahmad et al (2006) claimed that dual filter media performs better in producing high water quality. This is because the BOPS layer can remove bigger flocs while sand layer can remove smaller flocs. Deep bed (depth) filtration is virtually ubiquitous in the treatment of surfaces waters for potable water supply. In spite of its application in the water treatment processes, installation direct for stormwater rainwater harvesting could become one of important water reuse 302

2 opportunity. Rainwater is commonly harvested from roof top but using the ground collection is quite rare. Stormwater can be an excellent harvested surface water resource, especially due to the high rainfall intensity in Malaysia which approximately > 12 mm/h (Varikoden et al., 2011). Furthermore, the impervious surfaces in urban areas usually produces high stormwater, which may comprising of runoff from parking lots and other ground level run-off. Hence this study propose a modified deep bed filter utilizing dual media and propose an agricultural waste by product such as palm oil shell as media bed as a basic treatment of stormwater to be safely used for non-drinking purpose. In this research, utilizing laboratory scale of deep bed column, BOPS and River Sand media were further explored by investigating the removal of total suspended solid (TSS) and turbidity efficiency based on the fineness of the filter media. This work focus on the filtrate water quality, filter media properties and its effective size, and the mix ratio of design filter column. MATERIALS AND METHODS Stormwater Sample Preparation and laboratory testing To determine the stormwater properties, three storm water samples were collected from different location around Sepanggar using sample bottles. Then, the samples were analysed within one hour at School of Engineering Laboratory (Environmental lab) at room temperature to avoid any excessive agitation or prolonged contact with air reaction variations. Furthermore, sample bottles were filled completely and cap tightly. The samples were tested for total suspended solid (TSS) (ASTM D5907) and turbidity test (ASTM D7315) to classify the stormwater based on Interim National Quality Standard (INWQS) for Malaysia parameter. The average TSS and turbidity value were taken as the reference for feed tank water properties for deep bed filtration testing. To determine the efficiency of filtration filter bed design, before and after filtration (filtered at effluent tank) was analysed in terms of suspended solid, and turbidity properties. Filter Media Preparation and Properties for Deep Bed Column Design Prior to filtration as filter bed, both burnt oil palm shell (BOPS) and river sand were prepared and sieved to acquire the specific effective size. The properties of filter media such as specific gravity, absorption (ASTM C128) and moisture content were also determined. Both filtration efficiency between River Sand and BOPS were analyzed based on the removal of physical suspended solid and turbidity. Due to the dust and oil coating, BOPS undergoes pre-treatment. The air dried shells were sieved to remove fibers and rinsed in hot water to remove impurities. Then BOPS were crushed into 0.5 mm to 2.0 mm as fine grain and 1.0 mm to 2.5 mm as coarse grain. Coarse river sand was bought from local supplier whereas the original sand media was used as fine sand media. Deep Bed Filter Column The deep bed filter column (Model: SOLTEQ TR 13) at the laboratory of environmental Engineering UMS has been utilised to study the efficiency of filter media design. The unit consists of a column packed with filter media, a transfer pump, two sump tanks, a flowmeter and a bank of manometer tubes and various valves for flow control and samplings. 303

3 RESULTS AND DISCUSSION Influent Stormwater Quality The influent water quality is primarily dependent on the existing urban stormwater characteristic which samples have been collected from the Sepanggar resident area, Kota Kinabalu. As tabulated in Table 1, average value of ±73 mg/l for suspended solid content and 172±69 NTU for turbidity is determined based on the on-site sampling in Sepanggar stormwater. The range of TSS and turbidity of the stormwater samples were quite large and hence this work only focused on 150mg/L of TSS in the influent as a control to measure the performance and reduce the variation of filtration. The result of stormwater influent in Sepanggar is at similar range to the worldwide review conducted by Duncan (1999). He highlighted that the suitable concentrations of total suspended solid of 150 mg/l of the similar condition was been used with the relatively turbidity value would be excess of 50 NTU. This is consistent with the average result for Sepanggar determined and found to be categorised under the class III based on the Interim National Water Quality Standards (INWQS) for Malaysia. The influent water sample is a compromised to be semi-synthetic stormwater by using the dry soil which collected from the construction site surround the sampling point. In this study, Class III stormwater was used in the filtration process and clean water was used for backwashing operation. Table 1: The properties of the collected stormwater sample in Sepanggar Parameter Sample Average S1 S2 S3 TSS (mg/l) ±73 Turbidity ±69 Filter media properties Filter material properties for each group of filter bed which are fine River Sand, coarse river sand, fine burnt oil palm shell (BOPS) and coarse burnt oil palm shell (BOPS) are determined as given Table 2. Table 2: Filter media properties Properties Fine RS Coarse RS Fine BOPS Coarse BOPS Specific Gravity Absorption (%) Moisture Content (%) Effective Size (mm) Uniform Coefficient As tabulated in Table 2, it is observed that the specific gravity of the fine BOPS (Es=0.85 mm) and coarse BOPS (Es=2.4 mm) properties are 1.39 and 1.37, respectively. It was found that the bigger the sample size, the lower the specific gravity. While the absorption for BOPS is likely 26.75% ± 1.15%. This is consistent with earlier study conducted by Mannan and Ganapathy (2004). The finding indicates that the oil palm shell for size range 5 mm to 12.5 mm owns the specific gravity of 1.17 and absorption of 23.30% in their physical properties research of oil palm shell. At the same time, these results appear to match the BOPS properties investigated by Ahmad et al. (2006), that is, specific gravity of 1.40 at effective size of 2.0 mm. 304

4 In the related study of Tao and Karen (2008), the ideal filter medium is to have effective size between 0.3 mm to 1.5 mm where both fine RS and BOPS lie within the range. From Table 3, the uniform coefficient of RS and BOPS is less than 4.0 which to have adequate hydraulics conductivity and this minimize the risk of clogging (Tao and Karen, 2008). Filter Medium for Column Design Single media and dual media of were prepared by using BOPS and RS as filter media in deep bed filter column for both fine and coarse filter media. The combination of BOPS and RS for fine and coarse were prepared as shown in Table 3. Due to lower density of BOPS, the sand was placed at the bottom layer to avoid elution of uppermost layer during backwashing. The column filter design for two types of grain size namely fine and coarse grain were shown in Figure 1. Each column design were filtered with stormwater for two times after backwashing. Table 3: Different Set of Deep Column Filter Design Effective Size (mm) Column Filter Design Fine Grain Coarse Grain 100% RS % BOPS/ RS 0.7/ /2.4 50% BOPS/ RS 0.7/ /2.4 75% BOPS/ RS 0.7/ / % BOPS Figure 1: Arrangement sets of filter media in the column filter design (a-e) Deep Bed Column Design Filtration Efficiency Ten filtration experiments were conducted to evaluate the deep bed filtration efficiency as shown in Table 4. Experiment 1 to 5 are the fine sets column design, meanwhile experiment 6 to 10 are the coarse sets column design. For each experiment, the results of total suspended solids (TSS) and turbidity were tested prior before run and after filtration test and recorded. Filtration performance for first and second run after backwashing can be determined from Table 4. It is clearly showing that fine deep column filter provide better filtration compare to coarse deep column filter. Other than that, the combination of 50% BOPS and RS gives the best removal of TSS and turbidity, which is approximately 41% and 38% respectively. The result is supported with Ahmad et al (2006) which suggested that mixture of 50% BOPS and sand media filter is reliable highest. 305

5 Table 4: Experimental result for removal of TSS and turbidity for each filter medium No Filter Medium Removal of Total Suspended Solid (%) Removal of Turbidity (%) First Run Second Run First Run Second Run 1 i, J., Zivanovic, S % Fine BOPS/Sand % Fine BOPS/Sand % Fine BOPS/Sand % Fine BOPS % Coarse River Sand % Coarse BOPS/Sand % Coarse BOPS/Sand % Coarse BOPS/Sand % Coarse BOPS It was observed from the second time of filtration test, the efficiency was reduced significantly. From Table 4, second run of filtration s performance is not as optimum as the first run. This is because the pore of the media increased after backwashing and causing less filtration performance. The percentage of removal of TSS as illustrated in Figure 2 is highly dependent on the filter medium grain size. Coarser grain size especially dual media combinations were less affected to the efficiency removal of TSS compared to finer grain size due to less outflow losses during backwash. Whereas in term of turbidity removal, both fine and coarse grain have similar removal efficiency although after backwashing except for 25%BOPS could be due to some technical faulty during the experiment work. Figure 2: Influence of size toward (a)tss and (b)turbidity removal efficiency declining at second filtration run test CONCLUSION Based on the percentage of removal TSS and turbidity, it is suggested that dual BOPS/RS with the combination of 50% of fine BOPS and 50% of fine RS as deep bed filter column has provide the optimum filtration efficiency filter media design to produce removal of TSS and turbidity up to 41% and 35% respectively for a class III-Interim National Water Quality Standards (INWQS) stormwater and applicable to upgrade the storm water to Class IIB, which suits to recreational use and body contact. 306

6 ACKNOWLEDGEMENT The authors would like to thank the School of Engineering and Information Technology, University Malaysia Sabah for the support in this research. REFERENCES Ahmad, J., Goh, E.G., Nora aini, A., Halim, A.G., Noor, M.J.M.M. & Zakaria, M.P Comperative Performances of Single and Dual Media Filters of Sand and Burnt Oil Palm Shell. Jurnal Teknologi. 45 (F): Duncan, H.P Urban Stormwater Quality: A Statistical Overview. Cooperative Research Centre for Catchment Hydrology. 99/3, Melbourne, Australia. ASTM C Standard Test Method for Density, Relative Density (Specific Gravity), and Absorption of Fine Aggregate. Annual Book of ASTM Standards 2003, Pennsylvania: American Society for Testing and Materials. ASTM D Standard Test Methods for Filterable Matter (Total Dissolved Solid) and Non Filterable Matter (Total Suspended Solid) in Water. Annual Book of ASTM Standards 2003, 11.01: section Pennsylvania: American Society for Testing and Materials. ASTM D Standard Test Method for Determination of Turbidity above 1 Turbidity Unit (TU) in Static Mode. Annual Book of ASTM Standards 2003, Pennsylvania: American Society for Testing and Materials. Ahmad Jusoh, Noor, M.J.M. & Ghazali, A.H Potential of Burnt Oil Palm Shell (BOPS) Granules in Deep Bed Filtration. Journal of Islamic Academy of Science. 8(3): Rahman, S.S Evaluation of Filtering Efficiency of Walnut Granules as Deep-Bed Filter Media. Journal of Petroleum Science and Engineering. 7: Siemens Water Technology Coconut Shell Drinking Water Treatment. Retrieved on 1 December 2011, from Slava, K. & Douglas, W.L Deep Bed Nutshell Filter Evolution. Exterran Water Solutions: 20 TH Annual Produced Water Seminar Tao J. & Karen Mancl Determination of Sand Effective Size and Uniformity Coefficient. Sand Size Analysis for Onsite Wastewater Treatment Systems, AEX :