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| Problem 2 : River Pollution Attenuation in Aquifers Using Bank Infiltration Technique |
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BACKGROUND The population of Selangor has now reached around 6 million as of 2010 (Statistic Department, 2010). The rapid population growth in Selangor, along with unplanned urbanisation and industrialisation, overstrains the water supply infrastructure of the capital. In report of Malaysia Water Guide 2005, the water consumption in the state is very high. In 2003, metered domestic water consumption in Selangor was recorded at 478,995,217 cubic meters, while metered non-domestic water consumption was at 245,490,214 cubic metres. The total consumption of metered domestic and non domestic water in Malaysia in 2003 was 1,609,574,693 cubic meters and 843,388,420 cubic meters respectively. In Selangor, domestic demand grew at an average compounded rate of 5.9% from 1960 to 2006. That year, water demand was divided between the domestic and non-domestic sectors by a ratio of 61 to 39. The projected domestic and industrial demand for peninsular Malaysia up to 2050 based on study by Economic Planning Unit, under the National Water Resources Study (GOM, 2000), is about 4,753 million liters per day (MLD), and in 2008, it had almost tripled to 12,468 MLD and projected to reach 24,485 MLD by the year 2020. Demand projections for the Kuala Langat and Sepang districts shown the water demand is 330 MLD in 2010, but increase to 524 MLD in 2020. From the statistic of water consumption in Malaysia from 2008 until 2009 shows that there are about 12,418 water intakes in 2008, taking water directly from rivers for the water supply. The number of the water intakes and has risen to 12,583 in the year 2009 due to increased demand for water of the high demand for water, was feared that the incident would occur if the closure of water intakes are too dependent on the water surface. To meet future water requirements in the country, there has been a recommendation to build 47 new dams, besides three new inter-state water projects that include the Pahang-Selangor Inter State Raw Water Transfer. But, the infrastructure such as dams to treatment plants and distribution systems entails high investments. Operational costs such as energy and labour cost, and cost of maintaining the dams, treatment plants, distribution network, and pumps are no less costly. Langat River Basin is an important water supply source in the Klang Valley. There are two main dams that stored water from Langat River basin which are Langat and Semenyih Dams. Since the last 20 years, there were several occasions where water intakes and treatment plants have been closed as a result of serious river pollution. The closure of water intakes and water treatment plants have an impacts on water supply and thus on economic activities for industries and other sectors. The main sources of river water pollution were discharge of domestic sewage, pollutants from agro-based industries/farming, run-offs from earthworks and land clearing and effluent discharge from manufacturing activities. According to Khairuddin (2002), the sources of the Langat River pollution coming from industrial discharge (58%), domestic sewage from treatment plants (28%), construction projects (12%) and pig farming (2%). Department of Environment (DOE) of Malaysia, Ministry of Natural Resources and Environment of Malaysia, has monitor the water quality of river in Malaysia based on water quality index (WQI) evaluate the water quality status and river classification. The water quality in the basin has been deteriorating over the years, as evidenced from the water quality database compiled for 15 years. The recorded WQI ranged from 58.1 to 75, which corresponds to polluted (WQI, 0-59) and moderately polluted (WQI, 60-80). Based on the average values taken from the 2002 survey, the major pollutants in the Langat River Basin expressed as percentage of stations exhibiting quality corresponding to class 3 and above are as follows (figures in parenthesis indicate percent sampling stations): AN (94%), TSS and BOD (71%), COD (65%), and DO (53%; UPUM 2002). Data on the contamination of the Langat River has been published by various authors: for instance. In Malaysia, Zakaria, M.P and Mahat, A.A. (2005) report, the sources and concentration of polycyclic aromatic hydrocarbon (PAHs) in the river sediment in the Langat Estuary, that this area is dominated by pyrogenic sources which means that most of the PAH compounds are coming from the atmoshphere such as street dust. Farizawati et al. (2005) reported a study of Cryptosporidium and Giardia from cattle farms located near Sungai Langat and Semenyih river showed that out of 24 samples of water taken from Sungai Semenyih, 4.2% was positive for Giardia cysts with a concentration of 1.3 cysts/l and 20.8% were positive with Cryptosporidium oocysts with a range of 0.7-2.7 oocysts/l. In Langat river, from the 43 samples taken, 23.3% were positive for Giardia cysts with a range of 1.5-9.0 cysts/l whereas 11.6% were positive with Cryptosporidium oocysts with a range of 2.5-240.0 oocysts/l. This shows that wastewater was discharged into the river signifying contamination of (oo)cycts from the cattle farms into the river system. Liza, (2010) indentify the point source (PS) and non-point source (NPS) pollution using Geographical Information Systems during the base and stotrm flow event using the DOE data from 2004-2008 and ranked using the violation analysis showed are E.coli (NPS)> E.Coli (PS). TSS(NPS). COD(NPS)> NH3-N (NPS)>BOD(NPS)>COD (PS)>TSS (PS)> NH3-N(PS)>BOD (PS). It also found that the presence of E.coli in Langat river can reach 44 times higher than limiting standard of 2000cfu/100ml. The strong concentrations of BOD and COD are related to anthropogenic pollution sources from sewage treatment plants and industrial effluents. Lee, Y. H et al 2006, examining organochlorine insecticides from sediment and water of lake and Langat river. The results showed that endrin, chlordane and aldrin were present in all water samples with concentrations for endrin: 0.02-0.21  g/L, chlordane: 0.05-0.16 g/L and aldrin 0.03-0.13 g/L. Lindane and heptachlor were rarely detected in the water samples.
For sediment, lindane, endrin and heptachlor were detected in all sediment samples. Their levels in sediments were 0.28-0.53 g/kg for lindane, 0.06-0.53 g/kg
for heptachlor and 1.06-2.06 g/kg for endrin. The source would be from the river upstream flow through an area of oil palm plantation, where these insecticides
might have been used for pest control in the past. Osman, R. et al (2012), identifying sources of organic contaminants using chemometric techniques to classify
the pollution sources in Langat river basin based on the analysis of water and sediment samples collected from 24 stations, monitored for 14 organic contaminants
from polycyclic aromatic hydrocarbons (PAHs), sterols, and pesticides groups. They obtained from chemometric techniques indicated that sterols (coprostanol,
cholesterol, stigmasterol,  -sitosterol, and stigmastanol) are strongly correlated to domestic and urban sewage, PAHs (naphthalene, acenaphthene, pyrene,
benzo[a]anthracene, and benzo[a]pyrene) from industrial and urban activities and chlorpyrifos correlated to samples nearby agricultural sites. Othman M. S and Gasim M.B, (2005),
reported that heavy metal concentrations such as mercury (Hg), cadmium (Cd), zinc (Zn), lead (Pb), copper (Cu), nickel (Ni), iron (Fe), cobalt (Co) and manganese (Mn)
in water of Semenyih river watershed were determined in the water samples. Al-Odaini et al 2011, observed a pharmaceuticals in Langat river indicate that samples
collected from the remaining sampling stations along the Langat river were found to contain 15 out of the 19 targeted pharmaceuticals. However, chlorpheniramine,
lovastatin, simvastatin, and amlodipine were never detectable in any samples. The frequencies of detection for each pharmaceutical in all thirty samples are depicted.
Mefenamic acid, glibenclamide, and salicylic acid were present in samples from all the sampling sites, suggesting both their widespread use and their high degree of persistence in the environment. Metformin, chlorothiazide, and atenolol were detected in 83%, 80%, and 73% of the samples, respectively. On the other hand, nifedipine and loratadine have the lowest frequency of detection (6.6 %). The overall high pollution of the river has alarmed Malaysia scientists, population and authorities. In the past 20 years, judicial intervention and huge financial investment were undertaken to save the Langat, but despite all attempts both the contamination upstream of Langat river and the contaminant load from the urbanisation itself are still rising and need the Strategic Planning and Management for the Langat River Basin (U.N., 2005). Based on the previous study by some researcher in Malaysia, surface waters are not generally safe for human consumption unless they are properly treated.
In tropical countries like Malaysia where the rainfalls continuously recharge river flow, the main source of dependable water supply is essentially river water.
However, as development and economic activities spreads, the management of water resources can be very critical due to increase demand as well as environmental degradation. Pollution of rivers has made surface water unsuitable for sources of raw water for treatment and in certain cases has caused the treatment costs to rise unexpectedly. One of the alternative ways to improve dependable clean portable water supply that is being considered is through Bank Infiltration (BI) technology as a second source of water supply to guarantee clean and dependable water supply solution without neglecting the polluted surface water. To manage and protect the water supply, transport processes need to be predicted by using the BI method. To date, the method has mostly been studied by using mathematical solutions. To identify infiltration-related parameters, such as optimum pumping rate and distance between the riverbank and the production well, data on travel time, pathlines, and influence zone of river water were determined to characterize the interactions between water in the river and the alluvial aquifer are important factors that influence the BI method. The applications of mathematical solutions are important in transportation studies and to predict pathogen attenuation during transportation and artificial recharging. Primarily, the requirements for soil retention time need to be met to prevent pathogens and anthropogenic impact on the environment. Another goal of the mathematical solutions was to obtain pertinent data regarding BI implementation and its results, which can be used by water operators. | |
