Industrial effluent load characterization of Sungai Perembi watershed

Current concentration based environmental regulations are insufficient in dealing with the pollution of various water bodies, particularly issues pertaining to effluent discharge. It is no longer a question of effective implementation, but rather effective legislation. Concentration based standards fail to take into account critical factors such as Waste Assimilative Capacity (WAC) and Total Maximum Daily Load (TMDL), which are specific to a given water body and in association with assorted physical, chemical and biological characteristics. Sg. Perembi is located in the Pasir Gudang industrial area and receives primary effluent input from the various industries situated in that area. Water quality analysis, loading quantification and QUAL2E modeling of the watershed, not only give a systematic representation of the rivers’ ecological state, but also ease pollution control implementation strategies without incurring substantial cost. This is because Sg. Perembi experiences a dynamic distribution in overall pollutant species concentration, which is quite expected due to batch discharge practices. BOD5, COD and TSS concentration fluctuations are prominent in the overall river system. The study findings showed that the best control method would be via a Waste Load Allocation strategy (WLA). In general, a mass loading decrement of between 70% to 95% is usually required for compliance with Class III, Class II and Class I designators. This is done through the water quality modeling procedure, whereby after a precise representation of the aquatic body is achieved through QUAL2E, calibration efforts, through adjustments of concentration properties in the model is done to match the INWQS classes. Given that Sg. Perembi receives its base flow from industrial effluents as well as the short travel time of pollutants (< 5km), total load reduction was expected to be quite enormous as settling and decay phenomenon does not play a major role in the river’s WAC. BOD5 for example requires between 60% – 87% reduction in total load to achieve a Class IV denotation, whereas Class II and Class I compliances require an above 95% reduction. Abstrak : Perundangan masa kini berkaitan kawalan pencemaran jasad-jasad air yang berlandaskan had kepekatan, terutamanya dari segi pelepasan effluen tidak lagi mampu untuk membendung aktiviti tersebut daripada terus berleluasa. Perundangan yang berdasarkan had kepekatan ini tidak mengambil kira faktor kritikal lain seperti Kapasiti Asimilasi Bahan Tercemar (KABT) dan Had Beban Maksima Harian (HBMH). Faktor-faktor tersebut berkait khusus terhadap sesuatu jasad air dan ciri-ciri fizikal, kimia serta biologinya. Sungai Perembi terletak di kawasan perindustrian Pasir Gudang dan menerima bebanan effluen daripada pelbagai jenis kilang dan loji industri di kawasan berkenaan. Menerusi analisa kualiti air, pengiraan nilai bebanan dan simulasi berkomputer, didapati cara terbaik untuk menangani masalah pencemaran Sungai Perembi adalah menerusi Catuan Bebanan Bahan Buangan (C3B), di mana setiap punca pencemaran tetap dan spesis berkaitan ditetapkan kadar pelepasan maksimanya. Untuk BOD5 misalnya, pengurangan sebanyak 70% 95% daripada bebanan yang sedia diperlukan bagi menetapi syarat Kelas III, Kelas II dan Kelas I INWQS untuk sungai tersebut.