Maturity and hygiene quality of composts and hygiene indicators in agricultural soil fertilised with municipal waste or manure compost

Abstract

Composts produced from municipal source separated biowaste (Biowaste), a mixture of biowaste and anaerobically digested sewage sludge (Biosludge) and cattle manure (Manure) were examined for their maturity and hygiene quality. The composts were applied to a potato crop in 2004 and to a barley nurse crop of forage ley in 2005 in a field experiment. Numbers of faecal coliforms, enterococci, clostridia and Salmonella in field soil were determined 2 weeks and 16 weeks after compost applications. Municipal compost batches chosen based on successful processing showed variable maturity during field application, and the need to evaluate compost maturity with multiple variables was confirmed. The numbers of faecal coliform were similar in all compost types, averaging 4.7 and 2.3 log( 10) CFU g(-1) in the first and second years, respectively. The highest number of enterococci was 5.2 log(10) CFU g(-1), found in Manure compost in the first year, while the highest clostridia numbers were found in Biosludge compost, averaging 4.0 log(10) CFU g(-1) over both years. Except for one case, less than 2.4 log(10) CFU g(-1) of faecal coliforms or clostridia were found in compost-fertilised soil, while the numbers of enterococci were mostly higher than in unfertilised soil (<4.2 or <3.2 log(10) CFU g(-1), respectively). No hygiene indicator bacteria were present in compost-fertilised potato at harvest. Overall, compost fertilisations caused rather small changes in the counts of hygiene indicators in the field environment.

Design of a Bioreactor for Aerobic Biodegradation of Biowaste Based on Insight into Its Composition and Estimated Process Parameters

“…The results showed that, after 21 days in the reactor, about 50% of the volatile solids were degraded, which corresponded to the values determined in similar experiments and in practice under real conditions [37,38]. The specific aeration during the entire duration of the experiment was 0.55 L/min/kg The duration of biological treatment at temperatures above 50 • C depends on the type of microorganisms in the mixture and the type of biowaste and can last from a few hours to several days [32,33]. For the substrate used, i.e., the biowaste sample, according to the European and Mediterranean Plant Protection Organization-EPPO (2008) and German "Ordinance on the Utilisation of Biowastes on Land used for Agricultural, Silvicultural and Horticultural Purposes-BioAbfV (1998) [34], it was necessary to prolong the thermophilic phase in a closed biowaste mixture and keep it at 55 • C for 14 days (consecutively) or at 60 • C for 7 days (consecutively) and at a moisture content of 40% and more to ensure hygienization.…”

Stability and maturity of biowaste composts derived by small municipalities: Correlation among physical, chemical and biological indices

“…Although at the end of the monitoring period, both the laboratory tests and the on-site tests indicated stability, this condition was indicated more rapidly (on day 86) in the laboratory tests, namely RI and the self-heating potential. This also indicates that the decisions based on only one quality test can be erroneous and it is necessary to simultaneously perform more tests to reach a decision (Komilis and Tziouvaras, 2009;Tontti et al, 2011).…”