Green Engineering: Designing Biogas Plant to Optimize Waste Management

Biogas is a sustainable and renewable form of energy, produced from organic waste matter that is all around us. Biogas plants are typically fueled by waste from feed stock or animal manure, but researchers and industry stakeholders are becoming more creative in their approach to make biogas not only more sustainable, but also an extremely useful tool for treating organic waste. Now a Spanish research and development team from Demede Engineering & Technology is utilizing a pilot biogas plant that was developed at the request of the Universidad de Cadiz, to assess the viability of using anaerobic digesters to transform organic waste in landfills, wastewater, sewage sludge, and purification plants into biogas.

Designing a Biogas Plant that Adheres to the 12 Principles of Green Engineering

Utilizing the principles of “green engineering”, the plant generates biogas — consisting of a combination of methane, carbon dioxide and hydrogen — produced as a result of biological processes performed by anaerobic bacteria in an oxygen-free environment as they break down organic matter. The gases produced can stored and used to produce heat or electricity. “This prototype will serve to optimize the processes that make use of waste material to produce energy and will be a useful instrument for solving the problem of managing potentially toxic wastes in urban, agricultural and livestock areas,” explains the company's director of engineering, Javier Roa Fresno. The prototype biogas plant was developed and designed by a team of multi-discipline engineering experts whose skills and knowledge ranged from process and control engineering, electronic engineering, and mechanical engineering, to name a few. Their goal was to design a biogas plant that was both operationally efficient and economically efficient, that offered the highest waste reduction, and was easy to maintain.

How the Biogas Plant Prototype Works

The pilot biogas plant consists of a main reactor, which is basically a stirred tank reactor within which pH and temperature are controlled. The way the system works is relatively straightforward: organic matter is continuously added, which is then broken down by anaerobic bacteria who produce biogas during the metabolic process. The company is planning to offer similar systems that can be used to treat waste generated from agriculture and aquaculture, as well as mud and sludge produced during water purification processes, to both local and international clients soon. "Since the equipment is used for R+D at the university, it includes some additional equipment that makes the process more versatile," said Javier Roa Fresno. "The ultimate goal is to develop the technology and optimize the processes that lead to energy production on an industrial scale, using organic waste," he concludes.

Sustainable Energy Production

There is no shortage of organic waste; it is continuously produced at aquaculture farms, agricultural farms, wastewater treatment facilities, and landfills. By converting this waste into biogas, we will not only effectively manage out waste stream, but also produce a viable source of renewable energy that will reduce our dependence on dirty fossil fuels. Further Reading: Anastas, P.T., and Zimmerman, J.B., "Design through the Twelve Principles of Green Engineering", Env. Sci. and Tech., 37, 5, 94A-101A. http://pubs.acs.org/doi/abs/10.1021/es032373g

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