Waste pretreatment and recycling may harm the environment

According to a dissertation from Lappeenranta University of Technology (LUT), the waste pretreatment required in many waste treatment systems may compose a significant part of the environmental impacts of waste management. In some cases, the environmental impacts of mechanical waste treatment may even exceed the advantages of recycling.

The study analysed six different waste treatment systems and their impact on global warming, the decreasing of non-renewable natural resources, and toxicity to humans. The pretreatment required for waste reuse had the greatest impact when phosphorus was recovered from sewage sludge ash. Pretreatment accounted for 64 per cent of the environmental impact of the entire processing chain. This is due to the fact that the recycling of phosphorus from ash requires a great deal of energy and chemicals, and the reductions in greenhouse gas emissions are minor.

The pretreatment had the lowest human toxicity potential when the ash was recycled for road construction or garden stones. The pretreatment of ash does not affect toxic emissions that affect humans. In addition, the conventional waste disposal avoided and the recycling process itself have a great human toxicity potential.

 "The results indicate that pretreatment methods should be chosen carefully. We may otherwise, in the worst case, increase environmental impacts if some methods consume so much materials or energy that the impacts exceed those of conventional waste disposal or replacing the product," says Researcher Ivan Deviatkin.

Therefore, it is recommendable to find out about the environmental impacts of any planned pretreatment or recycling techniques in advance. To achieve the high recycling rates required by legislation, more advanced pretreatment and recycling methods will likely be needed in the future, and they may require more energy and materials.

Ivan Deviatkin, M.Sc. (Tech.), defended his dissertation at LUT on 20 October 2017. The title of the dissertation is "The role of waste pretreatment on the environmental sustainability of waste management". The opponent was Professor Eva Pongcrácz from the University of Oulu. Professor Mika Horttanainen from Lappeenranta University of Technology was the custos.

The dissertation has been published in the university's publication series Acta Universitatis Lappeenrantaensis, publication number 764. ISBN 978-952-335-129-5, ISBN 978-952-335-130-1 (PDF), ISSN 1456-4491. An electronic version is available in the LUTPub database: http://urn.fi/URN:ISBN:978-952-335-130-1. Printed versions can be purchased from the Aalef bookstore, tel. +358 44 744 5511 kirjakauppa@aalef.fi, or the LUT Shop online store https://lutshop.lut.fi/

Author of the dissertation:

Name: Ivan Deviatkin

Year and place of birth: 1990, Pestovo, Novgorod, Soviet Union

Higher education: Master of Science (Technology), 2013, Lappeenranta University of Technology

Other degrees: M.Sc. (Eng.), 2013, St. Petersburg State Technological University of Plant Polymers

Employment: Doctoral student, LUT, 2014-

Further information:

Ivan Deviatkin, +358 41 709 9988, ivan.deviatkin@lut.fi