Instrumental characterization of organic wastes for evaluation of vermicompost maturity

Abstract

Instrumental analysis of vermicompost with the help of modern technologies provides essential information on its maturity, before it can be used for agricultural application. Nowadays, vermicompost is considered as a promising organic alternative to chemical fertilizers in agriculture and horticulture. The objectives of this review are to summarize the sophisticated instrumental techniques such as scanning electron microscopy (SEM), fourier transform infrared (FT-IR) spectroscopy, thermogravimetry (TG), ultraviolet-visible (UV-vis) spectroscopy techniques, physico-chemical parameters (pH, electrical conductivity, organic carbon content, C:N ratio, nitrogen, phosphorus, potassium, sodium, calcium) and biological indicator (germination index) to determine the maturity of vermicompost produced from organic wastes. These techniques are reliable, fast and are capable of tracking organic waste degradation during the bioconversion process and fertilizing ability of the final product. SEM analysis provides essential information on surface morphology of vermicompost samples. The SEM micrograph of final vermicompost reveals disaggregation. In contrast, the initial SEM micrograph reflects robust and relatively contiguous structures. FT-IR spectroscopy technique is used to confirm the decomposition of polypeptides, polysaccharides, aliphatic, aromatic, carboxylic, phenolic groups and lignin during vermicomposting of organic wastes. TG method is used to characterize organic waste mineralization where progressive reduction in the mass loss of vermicompost indicates net mineralization and degradation. UV-vis spectroscopy is used to assess the degree of humification. The sharp fall in humification index during vermicomposting process indicates high level of organic material humification. Changes in physico-chemical and biological parameters are also an indicative parameter for organic waste mineralization as well as vermicompost stability and maturity.

Analysis and advanced characterization of municipal solid waste vermicompost maturity for a green environment

“…During vermicomposting, the earthworms (Eisenia fetida) ingested and pulverized the initial waste mixture in the gizzard (Ali et al, 2015). Further disintegration of substrate material was assisted by different enzymes and enteric microbial activities mainly by hydrolytic bacteria present in the earthworm's gut (Arancon et al, 2005;Bhat et al, 2017). Our results are in consistence with Unuofin and Mnkeni (2014), who observed fine granular structure of vermicomposts produced from cow dung and paper waste mixtures.…”

“…Thermogravimetry (TG) is a thermal technique which is used to examine the changes in mass of a sample at increasing temperature and constant heating rate. TG analysis of substrate material at two-time intervals during vermicomposting revealed thermal stability of samples explained by mass loss due to dehydration, oxidation and degradation (Bhat et al, 2017;Khatua et al, 2018). The derivative thermogravimetric (DTG) curves were found from the first derivative of thermogravimetric profiles.…”

“…In vermicomposting, degradation of organic waste materializes through gut microbes of earthworm and results in a stable and mature vermicompost (Lim and Wu 2015;. Stable vermicompost is humus like material, having nutrient rich profile and plant growth hormones which can augment soil physico-chemical and microbial properties and enhance plant growth (Srivastava et al, 2016;Bhat et al, 2017).…”

Qualitative and quantitative characterization of municipal solid waste and the unexploited potential of green energy in Tunisia

“…Cherif et al (2009) and Gwenzi et al (2015) assessed the effectiveness of MSW application on agricultural soil in northern Africa arid climate and recommended using MSW compost at a rate of 40 Mg/ha to fertilize wheat crops. Many researchers (e.g., Abbasi and Gajalakshmi 2015;Bhat et al 2017;Sarkar and Chourasia 2017;Chaturvedi and Verma 2015) suggested adding different kinds of bacteria to improve the speed and quality of composting processes. Abbasi and Gajalakshmi (2015), for example, used termites to decompose substances which resist composting, vermin composting, or anaerobic digestion such as cotton waste, coconut shells, and torn jute bags.…”

Abono Orgánico Elaborado Con Lodo Residual Y Estiercol Equino a Través De Vermicomposteo: Una Propuesta Como Mejorador De Suelos

“…Sin embargo a partir de los 60 días fue disminuyendo, como se observa en la figura 4. Esta disminución del C orgánico durante el proceso de vermicomposteo sugiere que la degradación de la materia orgánica, (mineralización y madurez de la misma), es llevada a cabo por la lombriz de tierra y microorganismos, que de manera conjunta la utilizan como alimento y fuente de energía para el desarrollo de sus actividades bioquímicas, lo que concuerda con Amouei et al (2017) y Bhat et al (2017). Se sabe que la pérdida de la materia orgánica puede llegar hasta un 49 % debido a la actividad respiratoria de las lombrices y microorganismos (Deka et al 2011), que junto a la actividad enzimática favorecen la descomposición y reducción de los residuos orgánicos.…”