The contribution of water extractable forms of plant nutrients to evaluate MSW compost maturity: a case study

Abstract

were determined using FAAS; the N-NH 4 and N-NO 3 content was analysed using a SAN ++ SFA continuous flow colorimeter (Skalar Analytical B.V., Holland). The solubility index (I), presented as the percentage share of water-extractable forms of macro-and micronutrients in the total content, was calculated according to Eq. (1): p-macro-or microelement, pw-water-extractable form of element, pt-total content of the element. Statistical analysis. Results were statistically verified using Statistica 12.5. Means were compared by the Tukey test, at a confidence level of P < 0.05. Results and discussion pH and ec during composting. Changes in H + concentration were observed during composting of MSW, reflected by analysis of water solution pH (Table 1). The lowest pH values (6.9) were found for water extracts from raw material. During the composting process, the pH increased, with the highest values being observed at between 54 and 126 days. In the following phases of the composting process, a slight decrease in pH was observed (8.0-8.1), but the result was significantly higher than those observed in the first days of the composting process. The decomposition of organic matter, particularly its components like proteins, amino acids and peptides, causes the release of ammonium which contributes to an increase in pH 36. Changes in the EC of water extracts during the composting process were observed as well (Table 1). The values of this parameter depended on the length of the composting process, significantly decreasing with an increased in composting time. After about 54-70 days of composting, the EC value was about 2 mS/cm, and in the final phase it increased slightly to 2.15 mS/cm. From the 54th to 68th day of composting, we observed some stabilization of EC, and lower values with respect to that of the initial material, indicating a reduction in the amount of soluble salts in the matured compost. The results obtained, according to many authors 36,37 , suggest that the concentrations of soluble salts in the compost analysed here were in the range considered non-phytotoxic.

The Use of New Parameters to Optimize the Composting Process of Different Organic Wastes

“…This is in accordance with Puyuelo et al and Trémier et al who reported that, more so than the total amount of N, it is the soluble forms of the element that should be taken into consideration to optimize composting [14,16]. This is because soluble N compounds (i.e., amino acids, small peptides and ammonium-N) are easily available forms of N that microorganisms can use for their metabolism and growth [36,37]. With respect to TOC/WEN, TOC/ammonium-N, TOC/WEON, WEOC/WEN and WEOC/WEON ratios and their relationship with temperature parameters during the active phase of composting, the correlation found in the present work was negative.…”

Physical and Chemical Properties, Pretreatment, and Recycling of Municipal Solid Waste Incineration Fly Ash and Bottom Ash for Highway Engineering: A Literature Review

“…Furthermore, if the waste is not harmlessly treated, the remaining bacteria, viruses, heavy metals, and other pollutants will exist for a long time and may pollute the surrounding environment [15,16]. Composting refers to the treatment of degradable organic waste by biochemical technology [17][18][19]. e organics in the MSW are decomposed and converted into stable soil humus.…”

Effect of Differently Matured Compost Produced from Willow (Salix viminalis L.) on Growth and Development of Lettuce (Lactuca sativa L.)

“…However, it should be noted that the dynamics of these changes differed between the composting variants. They result mainly from the composition of the composted biomass and the intensity and direction of organic and mineral component transformations [8,9]. These phenomena are determined by the biodegradability of the substrates used and the conditions of the composting process [10].…”