Mechanical pre-treatment for separation of bio-waste from municipal solid waste: case study of district in Latvia

Abstract

The mechanical pre-treatment technologies are one of the solutions that are planned to be used in all waste management regions to separate biodegradable municipal waste in Latvia, thus inter alia contributing to implementation of the waste policy of the European Union. In Latvia recent research of the collected household waste composition shows that average bio-waste is 39 %. The article provides the results of experimental work for partly sorted municipal solid waste mechanical pre-treatment in Latvia. The goal is to detect the composition of sorted waste parts after separation by the drum screener for evaluation of the effectiveness of the mechanical pre-treatment. The experimental truckloads of the collected waste (bio-waste and partly sorted) were selected from the apartments in Broceni town during a period of one year (2017/2018). Each truckload was weighed and the mass balance of the materials was established. Mechanical pre-treatment equipment is the bag breaker, drum screener and magnetic separator. Samples were taken from partly sorted municipal solid waste in two fractionscoarse, fine. The composition was determined manually in 11 parts. The moisture of fractions was determined. Results-fine fraction is ~34 %, coarse fraction ~65 % and metal ~1 %; separation of biological waste at source variates from 62 % in the autumn to 17 % in the spring season by mass.

Particle Size Distribution in Municipal Solid Waste Pre-Treated for Bioprocessing

“…This is explained by the fact that even before shredding the waste already had an inherent component of smaller particle sizes. Presence of such small particles in MSW was previously reported in literature [56,57].…”

“…This supports the earlier observation that MSW contains a substantial inherent fraction of small-size particles (usually around 5% and up to 10% w/w of <5 mm in the earlier trials of this study) and suggests that this fraction incorporates a significant amount of inert material. It has previously been reported that the fine fraction of MSW contains elevated proportions of inert materials such as sand [56]. The presence of sand and similar inert materials is unfavourable in bioprocessing, since it causes abrasion of technical equipment, reduced operating reactor volume as result of accumulating inert fractions (in particular in wet anaerobic digestion) and a need for regular removal of such material from the reactor [58].…”