Chemical and Biological Characterization of Organic Matter during Composting of Municipal Solid Waste

Abstract

Composting of municipal solid waste (MSW) was studied in an attempt to elaborate transformations of organic matter (OM) during the process and define parameters for the degree of maturity of the product. Composting was performed in 1‐m3 plastic boxes and the following parameters were measured in 13 samples during 132 d of composting: temperature, C/N ratio, ash content, humic substance contents, and fractions (humic acid, fulvic acid, and nonhumic fraction‐HA, FA, and NHF, respectively). Spectroscopic methods (CPMAS 13C‐NMR, DRIFT) were used to study the chemical composition of the OM. A bioassay based on growth of cucumber (Cucumis sativus L. cv. Dlila) plants was correlated to other parameters. The C/N ratio and ash content showed a typical high rate of change during the first 60 d and reached a plateau thereafter. The HA content increased to a maximum at 112 d, corresponding to the highest plant dry weight and highest 1650/1560 (cm−1/cm−1) peak ratios calculated from DRIFT spectra. 13C‐NMR and DRIFT spectra of samples taken from the composting MSW during the process showed that the residual OM contained an increasing level of aromatic structures. Plant‐growth bioassay, HA content, and the DRIFT spectra indicated that MSW compost described in this study, stabilized and achieved maturity after about 110 d.

Controlling Ammonia Volatilization by Mixing Urea with Humic Acid, Fulvic Acid, Triple Superphosphate and Muriate of Potash

“…The soil pH was determined in a 1:2.5 of soil: Distilled water suspension and 1 M KCl using a glass electrode. Soil organic carbon was determined by 58% of the total loss of weight on ignition [10] . The hydrometer method was used to determine soil texture [11] .…”

“…The extraction and fractionation periods used were 24 h. Humic acid and FA was isolated using 0.05 M KOH and 6 N H 2 SO 4 , respectively. Total organic carbon was determined using loss on ignition method [10] . The carboxylic-COOH, phenolic-OH functional groups and total acidity were determined by the method described by Inbar et al [14] .…”

Reducing Ammonia Loss from Urea by Mixing with Humic and Fulvic Acids Isolated from Coal

“…The HA and FA extraction was carried out by the methods of Stevenson [10] and Susilawati et al [11] with some modifications. Selected chemical and physical properties of soil, HA, FA and urea were determined using standard procedures.…”

“…Carboxylic-COOH, phenolic-OH and total acidity of HA and FA were determined using the method described by Inbar et al [16] . Level of humification (E 4 /E 6 ) of HA and FA was determined by spectroscopy [10] . The E 4 /E 6 was determined at wavelengths of 465 and 665 nm.…”

Reduction of Ammonia Loss from Urea through Mixing with Humic Acids Isolated from Peat Soil (Saprists)

“…Soil pH was determined using a glass electrode on a sample soil and 2 N KCl in a ratio of 1:2. Organic carbon was determined by combustion method [12] . Soil CEC was determined by leaching with 1 M ammonium acetate buffer adjusted to pH 7.0 followed by the steam distillation technique.…”