Factors influencing utilization of municipal solid waste compost among urban farmers in western Uganda

Background Effective management of solid waste is one of the most serious environmental problems confronting urban governments in developing countries due to insufficient financial resources and institutional capacity to provide basic solid waste management infrastructure, impoverished urban populations, low rates and coverage of collection, and rising food consumption rates. Composting has been touted as the most economical solution for reducing organic fraction of urban waste volumes while releasing vital nutrients for the soils. However, there is a paucity of information on utilization and associated factors of urban wastes in Uganda. This study aims to assess the level of utilization of Municipal Solid Waste (MSW) compost produced from Clean Development Mechanism (CDM) plants and associated factors among farmers in Fort Portal and Mbarara Municipalities, western Uganda. Methods Data was collected using a cross-sectional survey from 359 and 361 randomly selected farmers in Mbarara and Fort Portal, respectively. A semi-structured questionnaire was employed to collect quantitative data and analyzed statistically using SPSS and STATA statistical programs. Probit model was used to determine factors that influence farmers’ decisions to utilize MSW compost as a soil conditioner. Results The findings revealed a very low level of utilization in both municipalities, 1.7% in Fort Portal and 2.2% in Mbarara. The results indicated that annual farm income, access to other soil conditioners, experience with the use of fertilizers, membership to a farmers’ group and the cost of MSW compost significantly influenced farmers’ decision to use MSW compost. Conclusions The findings call for government investment in policies aimed at increasing the level of utilization of the MSW compost by improving accessibility to soil conditioners, creating opportunities for maximizing household incomes, farmer-to-farmer experience sharing, dissemination of information through extension programmes and other innovative communication approaches, operationalization of farmers’ groups and introduction of subsidy schemes on the price of compost through operational tax waivers in urban areas of Uganda. Finally, to guarantee quality and to improve the adoption of compost generated at the CDM plants, there is a need for research to assess the quality of MSW compost, undertake a supply chain analysis and cost–benefit study and set a price commensurate with the quality, and develop guidelines and rates of application of the MSW compost.

A study of triangular membership function and multiple regressions to calculate the MSW compost index

The municipal solid waste compost consists of elements with a varied composition, including light and heavy metal elements. For MSW compost to act as a soil conditioner, and to ensure agricultural stakeholders to believe in its use for crops production, validation of elements is obligatory. The triangular membership function evaluates each element of a fuzzy set for both discrete and continuous values, and regression analysis estimates the relationship between values. In this paper, a triangular membership function (μf) is studied and used to characterize the effect of individual elements available in the compost sample. The characterization determines the variation in the composition of elements in the compost sample and accordingly calculates its scorei. Furthermore, a reinvestigation is done by applying multiple regression analysis, especially on heavy metals, to compare their composition with light mineral nutrients and other supplementary elements. A relationship between R=4.12 and R2=0.067498635 is derived to determine the predicted value and defines the composition of heavy metals as attributed to another mineral nutrients. Furthermore, a correlation (Co) is derived to find the performance of the compost sample todecide whether both light and supplementary mineral nutrients are capable of minimizing the effect of heavy metals. A gratuity score (Gsi) is added to each heavy metal depending on the correlation value to form a composti. The scorei=88.11 and composti = 9.12 obtained, was summated to derive Ci=97.23, stating that the increase in score value declares that the compost sample is mature enough to be used for agriculture and enhance crops productivity.

Bioaccumulation of Chemical Elements in Vegetables as Influenced by Application Frequency of Municipal Solid Waste Compost

Municipal solid waste (MSW) compost is used to enrich soils by virtue of its bio-physicochemical properties. But undesirable accumulation of chemical elements can reduce soil quality and cause food safety issues. A 5-year field study was carried out to investigate the impact of Compost Quality Alliance tested MSW compost application frequency (annual, biennial and no-compost) on soil quality and chemical elements accumulation in edible portions of lettuce (Lactuca sativa cv. Grand Rapids), beets (Beta vulgaris cv. Detroit Supreme), carrot (Daucus carota cv. Nantes) and green bean (Phaseolus vulgaris cv. Golden Wax). Analysis of soil showed that chemical elements were highest in annual followed by biennial, but less in control (no-compost) and fallow soils. Soil background levels of chemical elements influenced the concentrations of iron and manganese in green bean, aluminum in green bean and beets, and barium in carrot, beets, and lettuce. Cadmium concentration in beets, lettuce, and green bean grown in annual plot was increased by 48%, 52% and 62%, respectively while carrot recorded 56% increase in the biennial plot compared to no-compost. Bioaccumulation factors < 1 for all the essential and non-essential trace elements in all the plant species except boron and molybdenum. However, lettuce showed a higher tendency to accumulate cadmium, rubidium, and strontium. Overall, the health risk for human consumption is low. Although long-term annual application of compost to vegetables seemed safe for human consumption, it is necessary to continuously monitor potential chemical elements accumulation, particularly non-essential trace elements in soils and plants.

Process modeling of municipal solid waste compost ash for reactive red 198 dye adsorption from wastewater using data driven approaches

In the present study, reactive red 198 (RR198) dye removal from aqueous solutions by adsorption using municipal solid waste (MSW) compost ash was investigated in batch mode. SEM, XRF, XRD, and BET/BJH analyses were used to characterize MSW compost ash. CNHS and organic matter content analyses showed a low percentage of carbon and organic matter to be incorporated in MSW compost ash. The design of adsorption experiments was performed by Box–Behnken design (BBD), and process variables were modeled and optimized using Box–Behnken design-response surface methodology (BBD-RSM) and genetic algorithm-artificial neural network (GA-ANN). BBD-RSM approach disclosed that a quadratic polynomial model fitted well to the experimental data (F-value = 94.596 and R2 = 0.9436), and ANN suggested a three-layer model with test-R2 = 0.9832, the structure of 4-8-1, and learning algorithm type of Levenberg–Marquardt backpropagation. The same optimization results were suggested by BBD-RSM and GA-ANN approaches so that the optimum conditions for RR198 absorption was observed at pH = 3, operating time = 80 min, RR198 = 20 mg L−1 and MSW compost ash dosage = 2 g L−1. The adsorption behavior was appropriately described by Freundlich isotherm, pseudo-second-order kinetic model. Further, the data were found to be better described with the nonlinear when compared to the linear form of these equations. Also, the thermodynamic study revealed the spontaneous and exothermic nature of the adsorption process. In relation to the reuse, a 12.1% reduction in the adsorption efficiency was seen after five successive cycles. The present study showed that MSW compost ash as an economical, reusable, and efficient adsorbent would be desirable for application in the adsorption process to dye wastewater treatment, and both BBD-RSM and GA-ANN approaches are highly potential methods in adsorption modeling and optimization study of the adsorption process. The present work also provides preliminary information, which is helpful for developing the adsorption process on an industrial scale.

Short term effects of Municipal Solid Waste compost, Khat-Derived Biochar and Co-composted Biochar on Soil quality and Faba bean Yield and Protein content

The effects of organic fertilizer to improve soil fertility and crop yield depend on the quality of organic fertilizer. The aim of this study was to test the short-term effects of the applications of municipal solid wastes (MSW) compost, co-composted biochar and biochar on soil quality and faba bean (Vicia faba L.) grain yield and protein content compared with mineral fertilizer. The study was conducted in a field experiment prepared in randomized complete block design with three replicates of each treatment from February 2019 to June 2019. The eight treatments were; control compost, 5%, 15% and 25% w/w co-composted biochars, recommended rate of mineral N & P fertilizer (NPF), biochar, compost + 50% NPF, and control soil. Results showed that the soil pH, organic carbon, total nitrogen, available phosphorus, exchangeable K+, Ca + 2 and Mg + 2 CEC and moisture in the residual soil were significantly increased in the municipal solid waste compost, co-composted biochar and khat-derived biochar amendments compared to the mineral NPF and control soil treatments. The faba bean grain yield was increased significantly (p < 0.05) by 34.2%, 33.7% and 30.% compared to the control soil and by 11.3%, 10.9% and 7.8% compared to the mineral NPF for the 5% co-composted biochar, compost + 50% NPF and control compost respectively. The organic fertilizer amendments with or without NPF applications were better than NPF alone with promoting nutrient concentrations, faba bean grain yield and protein contents. Thus, MSW compost and co-composted biochars are recommended because of their easy availability, sustainability and sufficient for proper growth of faba bean.

Heavy Metals Accumulations And Health Risk Assessment Of Faba Bean Grow On Soil Amended With Municipal Solid Waste Compost, Biochar And Co-Composted Biochar

Health risk assessment of heavy metals is crucial before large scale applications of municipal solid waste (MSW) as organic fertilizer. This study aimed to estimate Pb, Cd and Cr accumulation and health risk in faba bean (Vicia faba L.) grow on soils amended with MSW compost, biochar and co-composted biochars (5%, 15% and 25% w/w). The heavy metal concentrations were measured by flame atomic absorption spectroscopy. Bioaccumulation Factor (BAF), Estimated Daily Intake (EDI), Hazard Quotient (HQ) and Hazard Index (HI) were calculated. Results showed that Pb, Cd and Cr concentrations in the amended soils and faba bean grain were lower than WHO permissible levels. The EDIs of Pb, Cd and Cr in grains for all amendments were much lower than the reference doses established by USEPA and FAO/WHO. HQs and HIs of heavy metals were < 1 for all amendments indicating that consumption of faba bean grow on MSW compost, khat biochar and co-composted biochar collected from Jimma city was safe related to human health risks. Low accumulation of heavy metals in faba bean indicating that the low fraction of e-waste in the MSW. Since faba bean grain is not accumulator, it’s potential of heavy metals excluder needs further explorations.

Nutrient Enriched Municipal Solid Waste Compost Increases Yield, Nutrient Content and Balance in Rice

Globally a huge amount of municipal solid waste (MSW) is being produced which is very difficult to dispose. Composting of MSW is one of the options of solid waste recycling, but its use by the farmers is limited because of its low nutrient status. This study has considered some organic amendments to increase nutrient status of MSW compost for its potential use as an organic fertilizer in rice cultivation. We prepared three types of amended compost by mixing 20% mustard oil cake (MOC) and 30% poultry manure (PM) or cow dung (CD) or sugarcane press mud (SPM) with 50% MSW compost. The inoculum of Trichoderma viride was used to accelerate the composting process. The use of different amendments improved the nutrient level of MSW compost. A field experiment was conducted to evaluate the performances of amended MSW composts alone and in combination with chemical fertilizers on yield, nutrient content and balance in rice (var. BRRI dhan28). The experiment was conducted in 2018 at Bangladesh Agricultural University (BAU) farm, Mymensingh having silt loam texture, pH in water of 6.7 and 2.79% organic matter; the soil was Aeric Haplaquept under the order Inceptisols. There were 10 treatments consisting of chemical fertilizers (urea, triple superphosphate, muriate of potash, gypsum and zinc sulphate) and four types of MSW compost (three amended and one unamended). Based on the results of yield and N, P, K and S concentration of rice grain, the treatment containing 50% fertilizers +10 t ha−1 of amended compost (MSW + MOC + SPM in a ratio of 5:2:3) performed the best. There were apparent negative balances for N (11–45 kg ha−1) and K (6–48 kg ha−1), and positive balances for P (8–71 kg ha−1) and S (4–46 kg ha−1) in soils, across the treatments. Results of this study have significant value in fertilizer management strategies for rice cultivation in sub-tropical countries.

Effects of Nutrient Enriched Municipal Solid Waste Compost on Yield and Nutrient Content of Cabbage in Alluvial Soil

Composting of municipal solid waste (MSW) is a good option for solid waste recycling, but its use by the farmers is limited because of its very low nutrient status. Aims: The study aimed at nutrient enrichment of marketed MSW compost by using some organic materials and evaluating the influence of nutrient enriched MSW compost on yield and nutrient content of cabbage (Brassica oleracea L.). Place and Duration of Study: MSW compost amendment, field experiment and nutrient analysis were carried out at Bangladesh Agricultural University (BAU), Mymensingh during October 2017 to June 2018. Methodology: We prepared three types of amended compost by mixing 20% mustard oil cake (MOC), and 30% poultry manure (PM) or cow dung (CD) or sugarcane press mud (SPM) with 50% MSW compost. A liquid culture of Trichoderma viride was inoculated to every type of compost. The field experiment was conducted to evaluate the performance of the amended MSW composts on yield and nutrient content of cabbage (cv. Atlas-70), and on soil fertility. The experimental soil was silt loam having 6.7 pH and 2.79% organic matter; according to Soil Taxonomy it belongs to Aeric Haplaquept under the order Inceptisols. Results: Based on the yield and nutrient concentration (N, P, K & S) of cabbage, the treatment containing 50% fertilizers + 50% compost mixture (MSW compost + MOC + SPM in a ratio of 5:2:3) demonstrated the best result followed by poultry manure amended compost. Use of the amended composts had residual effects on soil showing an increased N, P, K & S content. Conclusion: Organic amendment of MSW compost inoculated with Trichoderma is a noble means to increase the nutrient status of marketed MSW compost and improve the soil fertility and crop productivity. The results have significant value in fertilizer management strategies for vegetables cultivation in sub-tropical countries.