Kajian ini mengkaji kesan pembudayaan keusahawanan ke arah mempengaruhi kecenderungan 

pelajar untuk menceburi bidang keusahawanan di kalangan bakal graduan di Universiti Tun 

Hussein Onn Malaysia (UTHM). Kajian ini dijalankan menggunakan kaedah kuantitatif. Untuk 

kaedah kuantitatif penyelidik memilih untuk menggunakan borang soal selidik untuk 

mendapatkan data. Sampel kajian kuantitatif terdiri daripada 120 orang bakal graduan dari dua 

buah fakulti di UTHM iaitu Fakulti Kejuruteraan Awam dan Alam Sekitar (FKAAS) dan Fakulti 

Pengurusan Teknologi dan Perniagaan (FPTP). Data Kuantitatif dianalisis menggunakan perisian 

SPSS 17.0 (Statistical Package for Social Science). Dapatan kajian ini mendapati bahawa 

kebudayaan keusahawanan di UTHM masih diperingkat awal. Akan tetapi telah wujudnya 

ekosistem keusahawanan secara kecil-kecilan dalam usaha menggalakkan pelajar menceburi 

bidang keusahawanan. Selain itu, kajian ini juga mendapati tidak wujud perbezaan

kecenderungan menjadi usahawan dalam kalangan bakal graduan di FKAAS dan FPTP

Mohd Rosli, Farhana

English

UTHM Institutional Repository

FIRST FLUSH LOADING OF POLLUTANTS FROM URBAN STORM RUNOFF IN SKUDAI JOHOR SITI NAZAHIYAH RAHMAT PROSIDING KEBANGSAAN AWAM 2007 29 - 31 MEI 2007 LANGKAWI KEDAH SO First Flush Loading of Pollutants from Urban Storm Runoff in Skudai, Johor 1 Siti Nazahiyah Rahmat, 2Zulkifli Yusop 3Ismail Abustan 'Department of Water and Environmental Engineering, Faculty of Civil Engineering, Universiti Tun Hussein Onn Malaysia, 86400 Batu Pahat, Johor depar tment of Hydraulic and Hydrology, Faculty of Civil Engineering, Universiti Teknologi Malaysia, Skudai, Johor. 3School of Civil Engineering, Universiti Sains Malaysia, Engineering Campus, 14300 Nibong Tebal, Pulau Pinang. E-mail: 'nazahiya@kuittho.edu.my,2 zulyusop@utm.my Abstract Runoff of eight storm events from residential (3.34 ha) and six events from commercial (0.75 ha) catchments were sampled to investigate the first flush phenomenon. The first flush was analysed by plotting the cumulative loading ratio against cumulative runoff ratio. The degree of flushing was higher in the commercial catchment as reflected by more points fall above the bisector line. Results indicated that the first flush phenomenon was greater in the smaller catchment. For the commercial catchment, the first 20 - 30% of the flow evacuated between 20-70% COD, 22-74% SS, 24-68% N0 3 -N , 7-69% NH3-N and 22-87% P. For the residential catchment, the first 20 - 30% of the discharges evacuated between 15-69% COD, 15-78% SS, 14-49% NO3-N, 23-53% NH3-N and 23-43% P. For both catchments, no correlation was found between the pollutant concentration and the antecedent dry weather period. Keywords: Commercial catchment, first flush, residential catchment, storm water runoff 1.0 Introduction Urban stormwater discharge is a major contributor to the pollution of receiving waters. It is also well known that constitu-ents transported in storm runoff are more concentrated at the beginning of a storm event than at the end of the same event (Sansalone and Cristina, 2004). This phe-nomenon is known as 'the first flush of storm runoff. For the past several years, many studies have been carried out to ana-lyse the existing of the first flush, but in Malaysia it is still very rare. There are many factors that affect the occurrence and impact of a first-flush event, such as the size and drainage characteristics of the catchment area, the imperviousness of the basin, rainfall intensity, antecedent dry weather period, and the mobility and prop-erty of the pollutants. However, some of these studies (e.g. Gupta and Saul, 1996; Lee et al., 2002) found no correlation be-tween the first flush and the antecedent dry weather period. The existence of first flush of pollutants provides an opportunity for stormwater managers and engineers to control water pollution in an economic and efficient way. If most of the urban-surface pollutant load were transported during the initial phase of a storm, then a small vol-ume of runoff storage would be needed to treat and remove the bulk of urban-surface pollutants. Controlling the first flush has become the most practiced criterion for the design of stormwater treatment facilities (Deng, 2005).The first flush phenomenon could be defined or evaluated using sev-eral methods. In this study, the analysis was done by plotting the cumulative load-ing ratio curve against cumulative runoff ratio. Besides, the relationship between the antecedent dry days and concentrations v re also examined. Pusat Pengajian Kejuruteraan Awam, Universiti Sains Malaysia 693 V /AWAM 2007 ProsirnngXeBangsaan Awam'07, Langkawi, Kedah, 29hb - 31hk Mei 2007 AWAM 2007 ProsWrlgKefiangsaan Awam'07, Langkawi, Kedah, 2<?b - 31"" Mei 2007 2.0 Methods 2.1 Study site The study site is located in Skudai, Johor, Malaysia. The residential catchment is 3.34 ha and the commercial catchment is 0.75 ha (Figure 1). The development in the residential catchment is mainly single sto-rey houses with 147 houses. The catch-ment represents a typical high density low cost residential area. It was estimated that about 15% of the catchment is still pervi-ous while the rest are roofs, pavement and road surfaces. Open spaces are located at the outlet of the catchment. For the com-mercial catchment, about 20% of the catchment is still pervious mainly covered by grass land while the rest are roofs, pavement and road surfaces. Legend m Houses Q Rain gauge i—. Pervious area a m a m m t Catchment boundary — Pavement roads Drainage network — M o n s o o n drain Scale 1: 4,200 TAMAN UNIVERSITI -J ALAN K E B U D A Y A A N CZJ Building • Rain gauge Pervious area * Catchment bounda^l ~ Residential area Drainage network Pavementroads Scale 1:7,000 Figure 1: Residential and Commercial Catchments 2.2 Runoff water quality sampling and analysis Samples are collected manually instead of using automatic water samplers. This is due to safety reasons as the site is very open to public. Although quite laborious, manual sampling could provide opportuni-ties to collect more samples at preferred time intervals. All bottles used for collect-ing samples were washed with dilute acid (sulfuric or hydrochloric) and thoroughly rinsed with deionized distilled water. It is very important to keep these bottles clean to ensure they were free of any contamina-tion. Pusat Pengajian Kejuruteraan Awam, Universiti Sains Malaysia 694 AWAM 2007 ProstaTftgKeBangsaan Awam'07, Langkawi, Kedah, 29hb - 31hb Mei2007 Table 1: Rainfall characteristics of monitored storms Site Event Rain-fall Inten-sity Days measured (mm) (mm/hr ) since last storm (hr) Resi- l l -Jan-04 1.52 3.5 120 dential 2-Mar-04 1.52 2.5 23 catch 4-Mar-04 18.8 16 45 ment 6-Mar-04 2.8 9.3 46.4 12-July-04 19 16 24 8-Sept-04 6.8 8.8 50 4-Nov-04 65 27 21 27-Dec-04 8 9.6 -Com- 8 mer- 21 cial 15 catch l l -Mar-04 20.1 10 24 ment 16-Mar-04 31.3 11 25 18-Mar-04 3 7 47.7 19-Mar-04 7 23.8 14-Apr-04 11 48 10-Sept-04 4.9 49 2.3 Characteristics of rainfall events Characteristics of and runoff data collected from November 2003 to December 2004 are summarised in Table 1. Eight storm events for the residential and six events for the commercial catchments were sampled and analysed. During the monitoring peri-ods, observed antecedent dry period ranged from 21 to 120 hours and the rain-fall size ranged from 1.52 to 65 mm. The storm depth and intensity are important for the transport of particulates whereas the length of dry periods indicate the amount of accumulated pollutant since the preced-ing event (Lee et al, 2004). 3.0 Results and Discussion 3.1 Event mean concentration (EMC) Due to high variability in pollutant con-centrations throughout a given rainfall -runoff event, a single parameter known as Event Mean Concentration (EMC) is often used. EMC of contaminants can be repre-sented by the total constituent mass dis-charged, during an event, divided by the total runoff volume of the event as follows (Adam and Papa, 2000); EMC=M = £ Qi C, At I I 0, At (1) V M is the total mass of pollutant over the entire event duration (g), V is the total vol-ume of flow over the entire event duration (m3), t is time (mm), Q, (t) is the time-variable flow (m3/min), Q is the time-variable concentration (mg/V) and At is the discrete time interval (miri) measured dur-ing the runoff event. Pusat Pengajian Kejuruteraan Awam, Universiti Sains Malaysia 695 Stormwater was grab-sampled using a 1-litre polyethylene bottle. Samples were taken when there was noticeable change in the water level. For every sample taken, the sampling time and water level were re-corded. About 10 to 15 samples were col-lected during each storm on both the rising and the falling limbs of the hydrograph. In the small catchment, more samples were collected on the rising limb than on the fal-ling limb. This is important to get a better description of the first flush phenomenon. Water samples were sent for analysis within 24 hours after sampling. The pa-rameters analysed were Chemical Oxygen Demand (COD), Suspended Solids (SS) and Nutrients (NO3-N, NH 3 -N and P). The laboratory analysis followed the Standard Methods for the examination of water and wastewater (APHA et al, 1995). The analysis of phosphorus was carried out us-ing Inductively Coupled Plasma-Mass Spectrometry (ICP -MS). AWAM 2007 ProstMg'Teb~angsaan Awam '07, Langkawi, Kedah, 29hk - 31hb Mei 2007 The loadings were than obtained by multiplying the concentration (EMC) from the flow-weighted composite sample by the total runoff volume for the event (Lee etai, 2004). 3.2 First Flush Analysis For a given catchment the pollutographs and hydrographs vary from one storm event to another depending on the rainfall intensity, the antecedent dry weather pe-riod, the condition of the sewer system, the dry deposits and the accumulation of pol-lutants. To resolve this discrepancy, Saget et. al. (1996) proposed a dimensionless represen-tation of cumulative loading ratio curve against cumulative runoff ratio or M(V) curve. Equations (2) and (3) represent the first flush phenomenon; L = m(t)l M F=v(t)/V (2) (3) where L is dimensionless cumulative pol-lutant mass; m(t) is pollutant mass trans-port up to time t (g); M is total mass of pollutant over the entire event duration (g); F is dimensionless cumulative runoff volume; v(t) is flow volume up to time t {m3) and V is total volume of flow over the entire event duration {m3). The diagonal line represents the loading of a hypotheti-cal pollutant with constant concentration. The loadings for COD, SS, NO3-N, NH3-N and P are plotted in Figure 2. Data points above the diagonal line repre-sent a higher loading and associated with pollutants that exhibit a seasonal first flush (Lee et al, 2004). Bertrand et al. (1998) defined first flush by the fact that at least 80% of the pollutant mass is transported in the first 30% of the volume. Meanwhile, Wanielista and Yousef (1993) proposed that 50% of the pollutant mass is trans-ported in the first 25% of the volume. In this study, for both catchments, most data points within the initial 30% of the runoff volume fall above the diagonal line. Table 2 shows averages cumulative pollutant loadings that fall in the 20-30% range of runoff volume. The mean values ranged from 0.38 to 0.55, with a maximum of 0.87. Since the average cumulative pollut-ant load that fall in the 20-30% range of runoff volume are considered, there is no first flush exist if the mean values was 0.25. It can be concluded that all contami-nants exhibited strong first flush. Table 2: Cumulative load at 20-30% of the runoff volume in the commercial catchments Commercial COD SS NO3-N NH3-N P Minimum 0.25 0.22 0.24 0.07 0.22 Maximum 0.82 0.74 0.68 0.69 0.87 Mean 0.54 0.48 0.46 0.38 0.55 Pusal Pengajian Kejuruteraan Awam, Universiti Sains Malaysia 696 AWAM 2007 ProsuWgKefiahgsaan Awam'07, Langkawi, Kedah, 29hb- 31hbMei2007 COD • Commercial • • r 0 0 'J 0 0 Dimen 2 0.4 0 6 0 8 \ sionless Cumulative Flow rate SS 'Commercial £ 1 Dimensionless Cumulative Flow rats NO,-N -Commercial Di mansion less Cumulative Flow rate NH3-N -Commercial Dimensionless Cumulative Flow rate P - Commercial • i m e r w o n l e s s Cumulative Flow rata Figure 2: Mass Volume, M (V) ratios of COD, SS, NO3-N, NH 3-N and P in the commer-cial catchment For the residential catchment, the mean flush with mean mass to volume ratio of values ranged from 0.17 to 0.47 as shown 0.47. in Table 3. SS showed the strongest first Table 3: Cumulative load at 20-30% of the runoff volume in the residential catchment Residential COD SS NO3-N NH3-N P Min 0.15 0.15 0.14 0.23 0.23 Max 0.69 0.78 0.49 0.53 0.43 Mean 0.42 0.47 0.3 0.38 0.33 Pusat Pengajian Kejuruteraan Awam, Universiti Sains Malaysia 697 AWAM 2007 ProsuWfKebWgsaan Awam '07, Langkawi, Kedah, 2<?b - 3Jhb Mei 2007 COD - Residential y isionlesB Cumulat ive Flow rate SS • Residential D i m e n s i o n l e s s Cumulat ive F l o w rate NHj-N - Residential warn W-\—— 0.0 0 .2 0.4 0.6 0.8 It D i m e n s i o n l e s s Cumulat ive F l o w rate NO-N -Residential 0 2 0 4 0.6 0.8 V D i m e n s i o n l e s s Cumulat ive F l o w r a t e 0.0 0 .2 0 4 0.6 0.8 D i m e n s i o n l e s s Cumulat ive F l o w r a t e Figure 3: Mass Volume, M (V) ratios of COD, SS, N 0 3 - N , NH 3-N and P in the residen-tial catchment The degree of flushing, however, was higher in the commercial catchment as re-flected by more points fall above the bisec-tor line. The first 20 - 30% of the flow evacuated between 25-82% COD, 22-74% SS, 24-68% N0 3 -N , 7-69% NH 3 -N and 22-87% P. For the residential catchment, the first 20 - 30% of the discharges evacuated between 15-69% COD, 15-78% SS, 14-49% NO3-N, 23-53% NH 3 -N and 23-43% P. In this study, it was found that the first flush was greater for smaller catchment area. Concentrations of SS, NO3-N, NH3-N and P are plotted against the antecedent dry days (Figure 4). For the commercial catch-ment, the observed antecedent dry days ranged from 24 to 49 hours and the rainfall size ranged from 3 to 31.3 mm. In-terestingly, even with less than 1 dry day period, the event on March 19, 2004 pro-duced the highest SS concentration com-pared to the other events. Storm size also didn't seem to be a single factor influencing the SS concentration. No correlation was found between the concentration of SS and the antecedent dry day period. COD shows the highest value of median concentration with 49 hours (2.04 days) antecedent dry day. But again there was no correlation be-tween COD and dry day period. The same case was found for the other parameters. For the commercial catchments, there was no correlation between pollutant concentration and the antecedent dry day period. This finding agrees with Gupta and Saul (1996). Since some kitchens in the residential catchments, especially after renovation, di-rectly discharge sullage into drains, the pol-lutant transport behaviour is less predict-able. Pusat Pengajian Kejuruteraan Awam, Universiti Sains Malaysia 698 /AWAM 2007 ProstMg'KeBangsaan Awam '07, Langkawi, Kedah, 29hb- 31hb Mei 2007 COD - Commercial SS - Commercial 0.99 1.04 2 1 1.99 2.04 DiyDays 0.99 1.04 2 1 1.99 2.04 Dry Days P - Commercial NHJ-N - Commercial N03-N - Commercial 0,99 1.04 2 1 1.99 2.04 Dry Days 0.99 1.04 2 1 1.99 2.04 0.99 1.04 2 1 1.99 2.04 Dry Days Figure 4: Effects of antecedent dry days on pollutant concentrations Concentrations of various pollutants of the residential catchments are plotted against the antecedent dry days (Figure 5). The observed antecedent dry days ranged from 21 to 120 hours and the rainfall size ranged from 1.52 to 19 mm. Similar to the commercial catchments, no discernible trend was found between pollutant concen-tration and the antecedent dry day period Pusat Pengajian Kejuruteraan Awam, Universiti Sains Malaysia 699 /AWAM 20Q7 ProsWMgXe^angsaan Awam'07, Langkawi, Kedah, 29hb - 3lhb Mei 2007 N03-N. Residential 0.88 1 193 5 0.96 1.68 208 Dry Days l i t 1.93 5 1.88 2.08 NH3-N - Residential COO - Residential l i I 0.88 t 0.96 1.88 2.08 .S6 t 1.93 5 0.96 1.88 Z.08 Figure 5: Effects of antecedent dry day on pollutant concentrations 4.0 Conclusion and Recommendations Despite limited samples, this study pro-vides interesting results on the occurrence of first flush phenomenon of pollutants in typical residential and commercial catch-ments. First flush loadings were greater in a smaller catchment. For the commercial catchment, the relative strength of the first flush was P> COD>SS> N0 3 -N> NH 3-N but slightly different sequence in the resi-dential catchment - SS> COD> NH 3-N> P> N0 3 -N . This preliminary finding is useful as basis for designing pollutant con-trol structure. It is more efficient to treat storm runoff during the early part of the storm events before it enters the water bodies. Future sampling design must include various lengths of dry period and rainfall intensity. Further analysis should be done to estimate the critical amount of runoff volume to treat the early runoff quality. Acknowledgement This study was financially supported by IRPA grant no 08-02-06-0011-EA14S. References Adams, B.J. and Papa, F. (2000). Urban Stormwater management planning with analytical probabilistic models, John Wiley & Son, New York. APHA, AWWA and WEF, 1995, Standard Methods for the examination of water and wastewater. Washington, DC: American Public Health Association, no 19. Bertrand, J.L., Chebbo, G., and Saget, A. (1998). Distribution of pollutant mass vs Pusat Pengqjian Kejuruteraan Awam, Universiti Sains Malaysia 7 0 0 /AWAM 2007 ProsWKftgKeffangsaan Awam'07, Langkawi, Kedah, 29hb-31hbMei2007 volume in stormwater discharges and the first flush phenomenon. Water Research, 32: 2341-2356. Deng, Z-Q, de Lima J.L.M.P. and Singh V. P. (2005). Fractional Kinetic Model for First Flush of Stormwater Pollutants. Journal of Environmental Engineering. 131 (2), 232-241. Gupta, K. and Saul, A. J. (1996). Specific relationships for the first flush load in combined sewer flows. Water Re-search, 30 (5): 1244-1252. Lee, H., Lau, S.-L, Stenstrom, M.K. (2004). Seasonal first flush phenomenon of urban stormwater discharges. Water Re-search, 38(19): 4153-4163. Lee, J. H., Bang, K. W., Ketchum, L.H., Choe, J.S. and Yu, M.J. (2002). First flush analysis of urban storm runoff. The Science of the Total Environment, 293:163-175. Lee, J. H., Bang, K.W. and Lee, J.K. (1996). A study of runoff characteristics of pollutants in combined sewer overflow. Journal of Korean Society Environmental Engineering, 18(10), 1147-1160. Characterization and Load Estimation in Saskatoon, Canada. Journal of Environ-mental Engineering, 132 (11), 1470-1482. Saget, A., Chebbo, G. and Bertrand - Kra-jewski, J.L. (1996). The first flush in sewer systems. Water Science Technol-ogy, 33 (9), 101-108. Sansalone John J. and Cristina Chad M. (2004). First Flush Concepts for Sus-pended and Dissolved Solids in Small Im-pervious Watersheds. Journal of Environ-mental Engineering, 130 (11), 1301-1314. Wanielista, M.P. and Yousef, Y.A. (1993). Stormwater Management. New York, USA John Wiley and Sons, Inc. Pusat Pengajian Kejuruteraan Awam, Universiti Sains Malaysia 701 

Pembudayaan keusahawanan ke arah mempengaruhi kecenderungan menceburi bidang keusahawanan dalam kalangan bakal graduan di UTHM

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