PROBLEM STATEMENT
Oxidation pond techniques have become very popular with small communities because of their low construction and operating cost,
as well as a significant financial advantage over other recognized treatment methods (Hussein and Mohammed, 2007).
Oxidation ponds are stages in a water treatment plant in which solid effluent and organic matter are degraded anaerobically or aerobically.
Both of anaerobic and aerobic ponds utilize indigenous microorganisms in their treatment to breakdown solid content of effluent and degrade organic matter into carbon dioxide, water, and cell biomass.
To improve the efficiency of the water treatment, beneficial microorganism based product may be added to the ponds to provide efficient removal and break down of solid content of effluent and pathogens, which are generally not sufficiently removed by oxidation ponds. The microbial approach can help in purifying heavily polluted water especially area that exposed to sunlight. However, the right amount of the product must be determined to ensure that sufficient dose is added, thus maintaining its efficiency and prevent excessive use.
Therefore, the aim of this study is to utilize a mathematical model to determine the optimal amount of beneficial microorganism product (mPHO) to be used in order to improve water quality of Indah Water Konsortium (IWK) oxidation pond treatment plant. The mPHO's ability to photosynthesis and photometabolize many organic substances may help to reduce biochemical oxygen demand (BOD5), chemical oxygen demand (COD), total suspended solids (TSS), ammoniacal nitrogen (NH3-N), total coliform (TC), and E. coli (EC) content in wastewater
LITERATURE REVIEW
- Oxidation Pond
The oxidation pond system consists of two types of pond, an aerobic and an anaerobic pond. The anaerobic pond is the first pond in the treatment system while the aerobic is last pond in the system. Anaerobic pond is devoid of oxygen. This encourages the growth of anaerobic bacteria, which breakdown the solid content of effluent. This process removes much of the nutrient from the effluent. To operate well, deep of the pond must be 4 meters or more with relatively small surface are. This helps maintain a low oxygen content and high temperature, which help the survival of anaerobic bacteria. Anaerobic ponds operate best at a temperature of at least 20.5C. The discharge from anaerobic pond is devoid of oxygen and is only partially treated. It is toxic to most aquatic life and must pass through aerobic pond before discharging the effluent (Taranaki Regional Council, 2013). Layout of Indah Water Konsortium Oxidation Pond Treatment System is presented in Figure 1.
In aerobic treatment ponds, aerobic microorganisms use dissolved oxygen to degrade the organic matter into carbon dioxide, water and cell biomass. Passive or naturally aerated ponds rely on oxygen produced by phytoplankton during photosynthesis and to a lesser extent, diffusion of oxygen from the air into surface layers (Shilton 2005). Microorganism growth is rapid, and a large proportion of the organic matter is converted into cell biomass, which may also need to be treated and stabilized before the reuse of recovered sludge. Naturally aerated facultative ponds are suited to relatively dilute effluents and should be used only after an anaerobic pond has provided substantial treatment. Although they could be used as a standalone option, the required surface area would be too large to be economical, and poor water quality would restrict light transmittance and algal photosynthesis (Dairy Australia, 2008).
- Phototrophic Bacteria
Phototrophic bacteria are widely distributed in nature especially in aquatic environment. Phototrophic bacteria such as green sulfur bacteria, purple sulfur bacteria and purple non-sulfur bacteria usually found in anaerobic area. Both green sulfur bacteria and purple sulfur bacteria begin to take place the photosynthesis to consume hydrogen sulfide as an electron donor. The purple non-sulfur bacteria also begin to take place the photosynthesis to consume organic materials as an electron donor (N.S Vision, 2005). Apart from that, phototrophic bacteria also have high toxicity resistant level and able to utilize toxic substances as carbon source for growth and reproduction (Ding, 2008; Madukasi et al., 2010).
The genus of interested, Rhodospirillaceae (Purple non sulfur bacteria), currently are getting more and more attention of scientist, specifically for its incredible ability in waste water treatment and aquaculture farming. The spesies of popular would be Rhodopseudomonas palustris, Rubrivivax gelatinosa, Rhodobacter capsulata, R. spaheroides, Phaeospirillum fulvum. The purple non-sulfur photosynthetic bacteria constitute a non-taxonomic group of versatile organisms in which most can grow as photoheterotrophs, photoautotrophs or chemoheterotrophs, switching from one mode to another depending on conditions available, especially the following: degree of anaerobiosis, availability of carbon source (CO2 for autotrophic growth, organic compounds for heterotrophic growth), and availability of light (needed for phototrophic growth). Chemotrophic growth for the purple non-sulfur bacteria is achieved by respiration in the dark, although there are some exceptional strains and species which can obtain energy by fermentation or anaerobic respiration (Holt et al. 1994).
- Wastewater Quality
In Malaysia, the effluent of sewerage treatment must comply Environmental Quality Act (Sewage and Industrial Effluent) 1974. In this research, there few parameters are selected based on this standard which have determined as pH, Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Suspended Solid (SS), Ammoniacal Nitrogen (AN) and Oil and Grease. IWK also measure these parameters at the effluent system in order to control their treatment plant.
The level of pathogen in black water poses a threat to public health, if people get exposed to wastewater (Henrik and Larsen, 2004). This black water contains high concentration of organic matter, Nitrogen and also pathogenic bacteria such as E.coli.
Most of the new treatment plant includes biological treatment. Therefore, microbial parameters are important to evaluate the system. Two parameters are chosen in this research, namely Total Coliform and E-coli. The biological characteristics of wastewater are of fundamental importance in the control of disease caused by pathogenic organism of human origin, role played by bacteria and other microorganism (Nur Amani, 2007).
- Regulation
Effluent that is discharged upstream of a water supply intake should meet Standard A, while effluent that is discharge downstream has to meet Standard B (Nor Amani, 2007). Standard A is the most stringent standard enforced by the DOE due to the possibility that the water collected will end up being treated at a municipal water treatment plant as drinking water. These standards are According to Malaysia's Environmental Law, Environmental Quality Act, 1974. Table 1 shows the detail values for each standard. Taman Timor Oxidation Pond effluent is discharge to Melana River which is tributary of Skudai River. The discharged outlets are located downstream of Skudai River. Therefore, the effluent must comply with DOE Standard B.
Table 1: Environmental Quality (Sewage and Industrial Effluent) Regulations 1979, Environmental Quality Act 1974
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