Currently the palm industry creates significant environmental pollution. This is partly due to the huge areas of land which have to be cleared, often by slash-and-burn agriculture for palm trees. This destroys habitats and produces a lot of greenhouse gas emissions. However, palm oil produces the most oil per land area compared with all other equivalent vegetable oil crops and so if it can be produced in a more sustainable way then palm oil is likely to be a more sustainable oil to produce in the future. The other key issue is that the palm industry generates palm oil mill effluent (POME) which is the wastewater produced in the production of palm oil. This pollutes freshwater and impacts biodiversity further downstream if it is not treated properly. This can therefore have knock on impacts on people using this now polluted water.
The Chitose group in Japan is using biotechnology to purify wastewater using microbes and aquatic plants. The aim of this project is to reduce the biochemical oxygen demand (BOD) of the waste fluids. In palm oil wastewater there is a large amount of biomass (living organisms in an ecosystem) which requires decomposition by microorganisms. To decompose this biomass, microorganisms digest it aerobically (using oxygen) this means that there is a high oxygen demand in the water. BOD measures the amount of dissolved oxygen which the microorganisms use and so gives an indication of the effect the water will have on the receiving environment. The high BOD of POME means that it can create damage to other ecosystems when it is released into watercourses. Algal blooms and eutrophication are a high risk due to the high quantities of water and large amounts of nutrients which enter the freshwater. This throws the ecosystem out of balance because plants such as algae can suddenly thrive in places they couldn’t before, impacting the food chain and sometimes producing toxins which directly impact other organisms. Moreover, the higher BOD values in POME means the bacteria needs more oxygen than the freshwater water contains which then leads to further issues. Plants and organisms (biomass) living in the water may die due to lack of oxygen. Anoxic zones may also occur which is where microorganisms begin to decompose matter anaerobically (without oxygen) due to lack of dissolved oxygen. Although some wastewater trestments do use anaerobic microbes to decompose matter, this is done in a heavily controlled environment. In a situation when it is un coton rolled there is potential to produce many harmful types of microbes. For example, anaerobic bacteria are responsible for the pungent smell of stagnant water as the process releases hydrogen sulfide and other noxious gases. Therefore, treating water to remove excess nutrients and ensure sufficient oxygen levels is essential for maintaining aquatic life and a healthy water source.
The way this process works is that microbes and bacteria are put in the POME to efficiently breakdown the organic matter and excess nutrients. This breakdown of nutrients creates an activated sludge which means that there are both microbes and undigested materials present. The sludge is aerated using machines which move the sludge to allow oxygen entry in order to promote further breakdown and growth of microbe populations. Over time, the microbes digest enough nutrients and organic matter in the effluent to make the runoff safe in freshwater: reducing the risk of algal blooms and reducing the BOD as fewer respiring organisms will be present when there is less organic matter.
Not only does this project benefit the local and global environment through cleaner water, reduced greenhouse gas emissions and a more sustainable production process of palm oil. It also has economic advantages as the gases produced by bacteria can be collected for biogas and excess biomass can be burnt for biofuel.