River treatment using biofilm growth on coconut and oil palm cellulosic fibres

Abstract

Many conventional treatments have been proposed to reduce river pollution issues in Malaysia. However, the application of these technologies is still expensive and sophisticated in terms of both operation and management. Recently, natural waste materials have been found to successfully treat different types of pollutants from contaminated water. Therefore, in this study, coconut fibre (CF) and oil palm fibre (OPF), two highly available natural materials in Malaysia have been selected for the development of adsorption and filtration materials. Instead of multi-purpose usage as furniture, slope protections and others, fibres (CF and OPF) can performed as a treatment medium for removing organic and nutrient pollutants, as well as providing an ideal biofilm formation platform to enhance removal rates. The main goal of this study is to develop biofilm on cellulosic fibres (CF and OPF) for organics and nutrients removal in river water and elucidate its adsorption mechanisms using modified empirical model. Desa Bakti River which is one of the polluted rivers in Johor, Malaysia due to domestic effluent discharge from nearby oxidation ponds was chosen as sampling site throughout the study. Initially various amounts of CF and OPF were tested in a jar test. Then, the obtained amount of fibres (CF and OPF) was used for organic and nutrient removal in a fabricated model with 0.2 m3 of river water at different flow rates. A same study that used the optimum flow rate was conducted again for biofilm developed fibres (CF and OPF). All the results were analyzed using modified empirical model. This model tested various loading rates and the predicted accumulation rate of adsorbates was found to decrease along with the percentage of outflows. It was discovered that CF with an attached biofilm have a higher mass transfer rate than OPF due to the fact that the thickness of the extracellular polymeric substance on CF was less than on OPF. The global mass transfer factor for the developed biofilm CF was found to be highest at 2% outflow, where chemical oxygen demand, total nitrogen and total phosphorus were 1.0067 d-1, 0.4857 d-1 and 0.1485 d-1 respectively. By using these modified empirical models as an analysis tool, the natural biofilm formation by using both CF and OPF were confirmed based on optimized yield in removal of organics and nutrients from river water.