Solving the Issues of Current Waste Water Treatment Practices Using Algae
It is a well known fact that the wastewater industry faces a lot of challenges for treatment. Major problems with current wastewater treatment practices include: High energy requirements , high operations and maintenance requirements, odor control in summer, sewer corrosion, sludge age ,ashing and gassing.
Many wastewater treatment processes generate large amounts of sludge that must be sent off-site for disposal. Handling and disposal of this sludge is typically the largest single cost component in the operation of a wastewater treatment plant. Most wastewater treatment processes cannot effectively respond to diurnal, seasonal, or long-term variations in the composition of wastewater.
A treatment process that may be effective in treating wastewater during one time of the year may not be as effective at treating wastewater during another time of the year. High energy requirements will make many wastewater treatment methods unsuitable for low per-capita energy consumption countries. High operation and maintenance requirements, including production of large volumes of sludge (solid waste material), make them economically non viable for many regions are also some of the major challenges faced by waste water treatment industries world over.
Using algae for wastewater treatment offers some interesting advantages over conventional wastewater treatment. The major advantages of algae-based waste water treatment are: Cost effective Low energy requirement Reductions in sludge formation GHG emission reduction Production of useful algal biomass
Cost Effective – It has been shown to be a more cost effective way to remove biochemical oxygen demand, pathogens, phosphorus and nitrogen than activated sludge process and other secondary treatment processes (Green et al., 1996).
Low Energy Requirements – Traditional wastewater treatment processes involve the high energy costs of mechanical aeration to provide oxygen to aerobic bacteria to consume the organic compounds in the wastewater, whereas in algae based wastewater treatment, algae provides the oxygen for aerobic bacteria. Aeration is an energy intensive process, accounting for 45 to 75% of a wastewater treatment plant’s total energy costs. Algae provide an efficient way to consume nutrients and provide the aerobic bacteria with the needed oxygen through photosynthesis.
Reductions in Sludge Formation – In conventional wastewater treatment systems the main aim is to minimize or eliminate the sludge. Industrial effluents are conventionally treated using a variety of hazardous chemicals for pH correction, sludge removal, colour removal and odour removal. Extensive use of chemicals for effluent treatment results in huge amounts of sludge which forms the so called hazardous solid waste generated by the industry and finally disposed by depositing them in landfills. In algae wastewater treatment facilities, the resulting sludge with algal biomass is energy rich which can be further processed to make biofuel or other valuable products such as fertilizers. Algal technology avoids use of chemicals and the whole process of effluent treatment is simplified. There is considerable reduction in sludge formation.
The GHG Emission Reduction – The US Environmental Protection Agency (EPA) has specifically identified conventional wastewater treatment plants as major contributors to greenhouse gases. Algae based wastewater treatment also releases CO2 but the algae consume more CO2 while growing than that is being released by the plant, this makes the entire system carbon negative.
Production of Useful Algal Biomass – The resulting algae biomass is a source of useful products such as biodiesel. Previous research in the early 1990’s by the National Renewable Energy Laboratory (NREL) showed that under controlled conditions algae are capable of producing 40 times the amount of oil for biodiesel per unit area of land, compared to terrestrial oilseed crops such as soy and canola (Sheehan et al., 1998). However, their results also showed that large-scale algae cultivation for energy production was uneconomical at that time and suggested future research into waste – stream integration (Sheehan et al., 1998). It is hoped that the economics will be ultimately improved by combining biodiesel feedstock production with agricultural or municipal wastewater treatment and CO2 fixation.
Read more from Oilgae’s Algae-Based Waste Water Treatment – The one and only such report in the world Oilgae has published a unique report to assist those keen on understanding the algae-based waste water treatment technology and those wanting to venture into this industry. The Oilgae’s guide to waste water treatment is a comprehensive guide to understanding the algae-based waste water treatment, technolgies, challenges and the players that are involved in this industry. Link –http://www.oilgae.com/ref/report/wastewater_treatment/wastewater_treatment.html
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