Chemical and biological properties of composts produced from organic waste

Abstract

The aim of the investigations was to determine the effect of composting municipal waste with various added substances (starch, edible oil or urea) on the content of selected forms of zinc, cadmium, copper and lead, the quality of organic matter and counts of some groups of physiological microorganisms. The above properties of compost may provide the basis for assessment of the composting process efficiency. The research object was biomass prepared from plant and other biodegradable waste generated in the area of Krakow. The biomass for composting was prepared from the following organic waste: deciduous tree chips, chicory coffee production waste, grass and tobacco waste. There were two stages of the composting process: I-lasting for 14 days, to obtain "heated" compost, and II-lasting for 210 days, when starch, edible oil or urea was added to the composted biomass. The total content of Zn, Cd, Cu and Pb determined in the analyzed composts does not pose a threat to the purity of the soil environment. The content of water-soluble forms of trace elements and forms bound to organic matter was affected by the loss of organic matter, chemical properties of a given element and the addition of supplement, mainly urea, to the composted biomass. Analysis of the fractional composition of humic compounds revealed higher values of the Cha:Cfa ratio in the composts with added edible oil or urea than in the other composts, which may indicate a much more advanced decomposition process of the material subjected to composting. Among the analyzed microorganisms, bacteria were most numerous in the composts. The introduction of urea to the composted biomass reduced microbial activity. Adding starch or oil stimulated microbial development and may have stimulated the composting process.

Food Waste Composting and Microbial Community Structure Profiling

“…The content of organic carbon in organic waste compost can be determined by using oxidation-titration with ferrous ammonium sulfate method followed by the process of mineralization in potassium dichromate [33]. The nitrogen content in the organic waste compost is determined by using the Kjeldahl method.…”

The dynamics of some physical and physico-chemical properties during composting of municipal solid wastes and biomass of energetic plants

“…Studies carried out by Chen et al (1996) and Drozd et al (2004) indicate there are pH changes during the composting process. The value of this parameter in the final phases is close or slightly higher than the initial value (Gondek et al 2014), whereas during maturation, small changes in pH are usually observed. These changes result from different intensities of biochemical processes occurring during composting, which depend mainly on maturing compost temperature, oxygen content and humidity.…”

Monitoring of Heavy Metals, Eox and Las in Sewage Sludge for Agricultural Use: A Case Study

“…The majority of these toxic metals accumulate in the sludge, since only a small amount is released with the treated final effluent (Sorme and Lagerkvist, 2002). Once sludge from WWTPs are applied to the soil, the degradation of organic compounds in sewage sludge affects the availability of heavy metals, inducing accumulation in plant biomass, one of the primary elements of the human food chain (Gondek et al, 2014). A recent study by Romanos et al (2019) highlighted that to reduce metals and pathogenic microorganisms in sludge in line with strict legislative limits, further processing (such as composting) may be required.…”