Nuhaa Soobhany

Current status of solid waste management in small island developing states: A review

This article reviews the current status of waste management in Small Island Developing States (SIDS) and the challenges that are faced in solid waste management. The waste generation rates of SIDS were compared within the three geographic regions namely Caribbean SIDS, Pacific SIDS and Atlantic, Indian Ocean, Mediterranean and South China (AIMS) SIDS and with countries of the Organisation for Economic Co-Operation and Development (OECD). Only Pacific SIDS had a waste generation rate less than 1kg/capita/day. The waste generation rates for the three SIDS regions averaged 1.29kg/capita/day while that for OECD countries was at a mean value of 1.35kg/capita/day. The waste compositions in the different SIDS regions were almost similar owing to comparable consumption patterns while these differed to a large extent with wastes generated in OECD countries. In SIDS, the major fraction of MSW comprised of organics (44%) followed by recyclables namely paper, plastics, glass and metals (total: 43%). In contrast, MSW in OECD countries consisted mainly of recyclables (43%) followed by organics (37%). This article also reviewed the other functional elements of the waste management systems in SIDS. Several shortcomings were noted in the process of waste collection, transfer and transport namely the fact of having outdated collection vehicles and narrow roads which are inaccessible. Among the waste management practices in SIDS, waste disposal via landfilling, illegal dumping and backyard burning were favoured most of the time at the expense of sustainable waste treatment technologies such as composting, anaerobic digestion and recycling.

Spectroscopic, thermogravimetric and structural characterization analyses for comparing Municipal Solid Waste composts and vermicomposts stability and maturity

This is the first-ever study of its kind for an extensive assessment and comparison of maturity indexes between compost and vermicompost that have been derived from Municipal Solid Waste (MSW). The spectroscopic (Fourier transform infrared spectroscopy: FT-IR), thermogravimetric analysis (TG), differential scanning calorimetry (DSC) and structural characterization (scanning electron microscope: SEM) were recorded. FT-IR spectra showed an increase in conversion of polysaccharides species and aliphatic methylene groups in vermicompost compared to compost as depicted from the variation of the intensity of the peaks. TG curves of final vermicompost showed a much lower mass loss when compared to compost, indicating higher stability in feedstock. SEM micrographs of the vermicompost reflected strong fragmentation of material than composts which revealed the extent of intra-structural degradation of MSW. These findings elucidate on a clear comparison between composts and vermicomposts in terms of maturity indexes for soil enhancement and in agriculture as organic fertilizer.

Inactivation of bacterial pathogenic load in compost against vermicompost of organic solid waste aiming to achieve sanitation goals: A review

Waste management strategies for organic residues, such as composting and vermicomposting, have been implemented in some developed and developing countries to solve the problem of organic solid waste (OSW). Yet, these biological treatment technologies do not always result in good quality compost or vermicompost with regards to sanitation capacity owing to the presence of bacterial pathogenic substances in objectionable concentrations. The presence of pathogens in soil conditioners poses a potential health hazard and their occurrence is of particular significance in composts and/or vermicomposts produced from organic materials. Past and present researches demonstrated a high-degree of agreement that various pathogens survive after the composting of certain OSW but whether similar changes in bacterial pathogenic loads arise during vermitechnology has not been thoroughly elucidated. This review garners information regarding the status of various pathogenic bacteria which survived or diffused after the composting process compared to the status of these pathogens after the vermicomposting of OSW with the aim of achieving sanitation goals. This work is also indispensable for the specification of compost quality guidelines concerning pathogen loads which would be specific to treatment technology. It was hypothesized that vermicomposting process for OSW can be efficacious in sustaining the existence of pathogenic organisms most specifically; human pathogens under safety levels. In summary, earthworms can be regarded as a way of obliterating pathogenic bacteria from OSW in a manner equivalent to earthworm gut transit mechanism which classifies vermicomposting as a promising sanitation technique in comparison to composting processes.

A comparative analysis of composts and vermicomposts derived from municipal solid waste for the growth and yield of green bean (Phaseolus vulgaris)

This work was conducted to evaluate and compare the responses of Phaseolus vulgaris to three types of composts and vermicomposts derived from municipal solid waste (MSW). Different amendment rates were used and evaluated for their effect on germination, growth, and marketable yield. MSW-derived vermicomposts and composts were substituted into mineral brown-earth soil, applied at rates of 0 (control), 10, 20, 30, 40, 50, and 100% (v/v) in plastic pots of 7.2-L capacity. Green beans which are grown in 40% vermicompost/soil mixtures and compost/soil mixtures yielded 78.3–89.5% higher fruit weights as compared to control. Results showed that MSW vermicomposts consistently outperformed equivalent quantities of composts in terms of fruit yield, shoot, and root dry weights, which can be attributed to the contributions of physicochemical properties and nutrients content (N, P, and K) in the potting experiments. Consequently, it seemed likely that MSW vermicompost provided other biological inputs such as plant growth regulators (PGRs) and plant growth hormones (PGHs), which could have a considerably positive effect on the growth and yields of P. vulgaris as compared to composts. More in-depth scientific investigation is required in order to identify the distinctive effects and the exact mechanisms of these PGRs in MSW vermicomposts which influenced plant growth responses.

Process parameters analysis for the vermicomposting of shredded paper using Pheretimoid Spp.

This study was to assess the effect of new species of earthworms; Pheretimoid Spp.on vermicomposting and compare the quality of vermicompost against compost produced from the same mix ratio of shredded office paper (SOP) together with grass clippings (GC) and cow manure (CM). Two composting experiments were setup in rotary drum composters namely: 1) composting of SOP, GC and CM followed by vermicomposting (denoted as reactor VC); 2) composting of SOP, GC and CM without the addition of worms (denoted as reactor C). The composting mixes consisted of a ratio of 1:4.3:3 on a mass basis of SOP, GC and CM respectively. When a temperature of 28–30°C was reached in reactor VC, adult Pheretimoid Spp. were introduced for the vermicomposting experiment. Copper and lead were found to be 44.8 mg/kg and 21.2 mg/kg, respectively for VC whereas a concentration of 51.2 mg/kg and 27.0 mg/kg were obtained in C. Cadmium was undetectable in vermicompost whilst 0.945 mg/kg of Cd was present in the compost. Analysis of the total nutrients content suggest that the amount of nutrients present (N, P, K, Ca, Mg) in VC was relatively higher than that of C with an increase of 0.05% to 0.23%.