According to world bank researchers, 2.5 million tons of plastic and other solid waste is generated every day all across the globe. Household waste, industrial waste, commercial waste, agricultural waste; all contribute to waste generation. This extensive amount of waste is treated in the wastewater treatment plants. The large scale and small scale processes lead to the development of various by-products which include methane gas or biogas which are used to power these plants. Recently, experts and researchers have found that wastewater treatment plants can be turned into sustainable biorefineries using new technology. This can lead to the extraction of chemicals and production of bio-based products. It will certainly boost the productivity of wastewater treatment plants and revolutionize biorefinery market too.
It is essential to understand in detail how wastewater treatment plant works, how does a biorefinery work and how wastewater treatment plants can be combined with biorefineries. Let’s dive into the details
How do wastewater treatment plants work?
Wastewater treatment plants consist of majorly three stages; Primary, Secondary and Tertiary. In the primary wastewater treatment stage, the physical devices or tools are used to clear out the solid waste from the wastewater. Several tanks and filters help in separation of wastewater from contaminants and what leaves behind is the sludge.
The secondary wastewater treatment involves the treatment of wastewater using biological processes like aerobic, anaerobic and anoxic. The aerobic process requires oxygen in the system to carry out the function of degrading solid waste. On the other hand, the anaerobic process takes place in the absence of oxygen. In these processes, microorganisms are used to act aggressively on the wastewater and thus breaking down the remaining solid organic waste present. This is the stage where various bioreactors are used to extract chemicals present in the organic matter. Know that it is through the anaerobic process, the resulting by-products are further processed to create methane gas, carbon dioxide and water. This process is relevant and important to associate it with biorefinery. More on that later.
The tertiary treatment of wastewater deals with removing unwanted substances like phosphorus and nitrates and thus purify water. Most of the time chlorination takes place in this stage and the effluent is ready to be released in the nearby environment after this process is carried out.
The wastewater treatment is done if different ways at different places according to the type of waste generated and the treatment required.
What are Biorefineries?
Biorefineries are known to convert biomass into energy, fuels, and value-added chemicals using various processes and equipments. It is a great alternative to conventional petrochemical based products as it can meet the energy needs, power production at a place and fuel to vehicles. The liquid fuel such as biodiesel can be produced which can directly replace the existing fuels used for transportation. It can be used to generate electricity and process heat. It is not limited to fuels and energy. But various materials like plastics, construction material, lubricants and adhesives can be made using this process. Also, it is in comparison, causes less pollution than their petrochemical counterparts when we take carbon dioxide and environment into consideration. Thus, one can conclude that bio-based fuel, energy and products are one of the leading sustainable solutions of the future.
It is one of the best ways to utilize organic waste and convert into a substantial amount of energy. This promises to reduce capital expenditures and growth of biorefinery market. The appropriate enzymatic or chemical treatment can help to convert biomass wastes into fuels. With all these positive factors in bio-based products, the market has not yet completely opened up to it. The high cost due to the extensive process involved and feed stock prices are seen to be the major obstacles. This is where the development of a wastewater treatment combined with the biorefinery ecosystem can be a game-changer.
The concept of wastewater biorefinery or WWBR is already under study and various researchers and expert see it as a viable option for treating waste as well as generating bio-based products for the future. This will increase the productivity of both systems. On one side, it will push the bio-based economy which will pave the way for a sustainable future and on the other side, wastewater plant profitability will increase and a reduction in releasing effluents to the surroundings will be achieved. There are two systems in place when we look to transform a wastewater treatment plant into biorefinery: Environmental biotechnology focused on achieving water without impurities and industrial biotechnology meant to get additional by products. There is a considerable amount of research and study to be done and design factors need to be discussed before we see the positive result.
How wastewater treatment plants can be transformed into Biorefineries?
Wastewater treatment plants across the world treat a large amount of waste and it is an opportunity for the biorefineries to, therefore, to integrate with it and create bio-based products from organic materials. As mentioned before, biogas is already produced by wastewater treatment plants in the anaerobic process in the secondary treatment stage. It is widely used to power the wastewater treatment plant itself. In this way, cost-savings can be done through it. Therefore, a broader function can be given to wastewater treatment plants by expanding its capabilities, according to new research carried out by University of Boras, Sweden. Similarly, as per scientists in Resource Recovery, they are working on the concept to produce and extract fatty acids using bioreactors. This can lead to the development of substances like acetic acid and hydrogen. New technologies can be used to develop and combine both systems and prepare different chemical compounds and make different products. As in the case with fatty acids, it can be used for the sustenance of microbes in the processes like that of sugar. The fatty acid can be further used to produce bio-plastics or butanol. The new methods also promises to extract carbon from the sludge and it can be prevented from reaching the water resources and eutrophication as well.
