Fraction Of Solid Waste Research Articles

Design of a stand‐alone 1000‐kW biogas power plant from codigestion of organic waste and microalgae grown in a tubular photo bioreactor at Bomaka‐Buea

Buea is connected to the south interconnected grid (SIG) of Cameroon. But the power supply is unreliable, not accessible to all and of very low quality. In addition, solid municipal waste generated in Buea is poorly collected by Hysacam and dumped at Musaka with no further valorization. There is an acute need to improve on the quantity, reliability and quality of the power supplied to inhabitants of Buea as well as to improve on the environmental management system of the town. In this study a project is proposed to design a stand-alone 1000-kW biogas power plant from the codigestion of organic fraction of solid municipal waste with microalgae (Chorella Sorokiniana) grown in tubular photo bioreactor (PBR) in Bomaka-Buea. As far as electrical energy production is concerned, the aforementioned anaerobic biological treatment unit will produce almost 9311.88 MWh/y. Assuming an average electricity consumption of 3 to 4 MWh/y/household the annual produced electrical energy from the anaerobic digestion (AD) unit could supply almost 3000 to 4000 households in the Municipality of Buea. So by treating the 39% of annual organic waste produced in Buea it can cover between 31.3% and 31.8% of Buea municipality's electrical energy demand. With a levellized cost of electricity at 0.265 $/kW and a net present value of 25.3million dollars if this energy is sold to the national grid then the annual profit of energy production will be around $4,188,888/y (assuming a selling price of 0.36 $/kWh) that is valid now in Cameroon.

Organic matter and nutrient removal in a combined anaerobic–aerobic fixed-bed reactor treating digestate from anaerobic biodigester

Anaerobic digestion has become a possible approach for treating organic fraction of urban solid waste. However, the treatment of the digestate is still a matter for technological development. In this work a single anaerobic–aerobic fixed-bed reactor subjected to recirculation was used to treat the effluent from an anaerobic digester fed with organic food waste. The reactor was operated for 100 days, with hydraulic retention time of 24 h. The organic loading rate applied was 1 kg COD m−3 d−1. The efficiency in removing nitrogen, organic matter, and phosphorus were 73%, 83%, and 23%, respectively. This reactor configuration proved to be quite promising to promote simultaneous removal of carbon, nitrogen, and phosphorus from effluents with high nitrogen and organic matter contents.

Controlling the soundness of Portland cement clinker synthesized with solid wastes based on phase transition of MgNiO2

A Portland cement clinker containing high content of ferrite phase (>18%) is synthesized with high fractions (60 mass%) of solid wastes, including steel slag, copper tailing, coal gangue and phosphate tailing. Controlling the soundness of clinker caused by the MgO (about 9% in mass) is the key challenge. Adding NiO into the raw meal of clinker controls its soundness via the formation of MgNiO2 with free MgO, showing little effect on the hydration and strength development of cement synthesized with solid wastes. The cement satisfy the 42.5 grade according to the Chinese standard GB 175–2007.

Application of Iron Ore Tailings and Phosphogypsum to Create Artificial Rockfills Used in Rock-Filled Concrete

Rock-filled concrete (RFC) has good performance in terms of energy savings, cost reduction, and CO2 emissions as a novel massive concrete construction technology. There have been studies into replacing natural rocks in RFC with large blocks of solid waste, and this method has been used on several construction sites. However, the granular and powdery solid waste utilized in RFC is limited, as a consequence of the special requirement of self-compacting concrete (SCC) in RFC. The goal of this paper is to increase the amount of granular and powdery solid waste in RFC. Iron ore tailing (IOT) and phosphogypsum (PG) were used separately as granular and powdery solid waste. The modified PG, ground blast-furnace slag (GBFS), steel slag, and cement clinker are combined to form parathion gypsum slag cement in a specific proportion, with the ratio of PG, GBFS, steel slag, and cement being 47:47:2:2. To replace the natural rocks in RFC, artificial rockfills made of IOT and parathion gypsum slag cement are used to increase the dosage of solid waste. The artificial rockfills were formed using three methods: compressing, roller compacting, and normal vibrating. When the compressive strength and material costs of the three types of artificial rockfills are compared, the compressing method is the best for maximizing the IOT. In artificial rockfills, the mass fraction of granular solid waste is 83.3%, and the mass fraction of total solid waste is 99.3%.

Mechanism of pH sensitive flocculation for organic load and colour reduction in landfill leachate

Landfill leachate has an important fraction of humic substances, mainly humic acids (HAs), which often represent more than half value of COD, specially in liquids proceeded from composting processes of organic fraction of solid wastes. We propose in this article a new method of pH sensitive flocculation for COD and colour reduction in landfill leachate based on the chemical properties of HAs. Landfill leachate with a high content of humic acids can be efficiently treated by pH sensitive flocculation at pH 2.0, reducing COD value in 86.1% and colour in 84.7%. Mechanism of pH sensitive flocculation is based in protonation first of phenolic groups and later of carboxylic acid groups in the HAs molecules, resulting in a reduction of Zeta potential value. For pH over neutrality, carboxylic acid and phenolic groups are ionized and Zeta potential increases in absolute value, maintaining HAs in suspension as colloids and conducting flocculation to be obstructed. Ionized anionic groups (carboxylates) can interact electrostatically with cations abundant in leachate (site binding) aiding to maintain HAs in suspension. Simulation of this situation and ideal visualization of Zeta potential behavior is described in the paper and aggregation of molecules by H-bonds is proposed as the main step in separation of HAs from leachate and reduction of COD value in this complex liquid. CHNS analysis, FT-IR spectrometry and UV–VIS spectrophotometry show chemical elements content in the range of natural and commercial HAs, clear aromaticity and carboxylic acids and phenolic groups presence in the precipitate from landfill leachate.

Physio-chemical evaluation and Co-combustion efficiency of different biomass waste fractions with indigenous coal blends for utilization as alternative fuel

<p>Severe energy crisis and vilest economic conditions in Pakistan demand the country’s energy portfolio to be revised with increased reliance on indigenous energy resources. The perspective of utilization of abundantly available biomass waste fractions as a fuel alone and their co-combustion with two different indigenous coal varieties has been emphasized in this study. Coal samples were blended with the organic fraction of municipal solid waste, rice husk and sugarcane bagasse waste fractions in varying ratios of 20%, 40%, 60% and 80% and the resulting variation in their fuel characteristics and co-combustion efficiency was determined. The execution is a basis to assess the assumption that co-combusion in appropriate proportions can arrange a solution for the massive amounts of produced organic waste and cut dependency on imported energy sources. The tanner diagram visualization for the assessment of proposed blends suggest that the blending samples exhibit an increase in moisture and combustible content while some decrease in ash content and calorific values with increased biomass ratios. Within the assortment of conducted trials, khaushab coal and rice husk in various proportions evidenced to be the best arrangement for fuel consumption based on energetic optimization. The overall results of studies inferred that both coal and biomass fuels alone and their co-firing can sustain self-combustion and subsequently arrange for finding area based solutions related to various energy operations.</p>

Snapshot review of refuse-derived fuels

Refuse-derived fuel (RDF) is generated by selected Municipal Solid Waste (MSW) fractions. Due to MSW composition changes by location, it is challenging to sell RDF as a product in the market. This article compiles the significant standards and rules governing RDF manufacture and usage. Additionally, it emphasizes the key actors that have already made a business of its commercialization and energy production through thermochemical processes. Combustion is the most often utilized thermochemical process, and this paper gathers information from several works on the combustion of RDF and RDF blends. Pyrolysis and gasification are also discussed, along with the primary benefits and drawbacks of RDF usage. Finally, the market's potential and significant constraints are examined. The primary constraint is the RDF price due to commercialization fees. However, RDF is aligned with the circular economy, sustainable development goals, and CO2 reductions by avoiding the extraction of new fossil fuels.

Factors and Constraints Hindering Effective Municipal Solid Waste Management Systems in Sub-Saharan Africa: Case Study of Northern Uganda

In developing countries, little information is available about solid-waste characteristics, determinants for adoption and performance-evaluation of municipal-waste management systems in Municipals. This study aimed: to characterize the municipal solid-wastes, collection, dumping and evaluate the efficiency and reliability of Municipal solid-waste management system. A total of 200 households were randomly sampled and interviewed. Data was analysed using Binary-Logistic Regression model to determine factors influencing collection and dumping of solid wastes. Results showed that biodegradable/organic wastes comprise a major fraction of solid-wastes produced. Factors that influenced solid-waste collection and dumping included: household-age, unavailability of solid-waste containers, inadequate collection/dumping space and weak legal-enforcement against poor-dumping. The waste system is constrained by inadequate transport facilities, inadequate space for temporal dumping; and lack of legal enforcement in matters of solid-waste poor handling. These have made the systems ineffective and unreliable. This study recommends involvement of all stakeholders in innovative approaches to uphold sustainable municipal sanity.

POWER-GENERATING FUEL BASED ON THE PROCESSING OF MUNICIPAL SOLID WASTE ORGANIC COMPONENTS

The article considers effective technologies for processing the organic fraction of solid waste, involving the use of various approaches with the concept of preserving the ecology of the environment. Biomass cannot be simply collected and burned, the authors suggest using an effective method of its processing, which will allow fuel from it. To obtain energy, biomass can be used to produce biogas or liquid biofuels using various technological processes, for example, by fermentation. They, in turn, can be converted into electricity and heat, through combustion or the creation of fuel cells or used as fuel for motor vehicles. The purpose of this article is to use alternative methods, such as pretreatment of the organic fraction of municipal solid waste, ethanol fermentation with alcohol yeast, and anaerobic digestion are attracting increased attention. Using these methods, a liquid with alcohol-containing substances has been obtained from 1.5 kg of the organic fraction of municipal solid waste, in which the percentage of ethyl alcohol was 97.5%. Therefore, organic municipal solid waste can be a promising source of fuel in modern energy.

Comparative Study on Anaerobic Degradation Processes of Pressed Liquid Fraction of Organic Solid Waste

Anaerobic degradation processes: anaerobic digestion (biogasification), biohydrogen fermentation (dark) and microbial fuel cells were applied to treat the organic fraction of a municipal solid waste. The processes were compared based on their ability of energy recovery and Chemical Oxygen Demand reduction.

An effective organic waste recycling through vermicomposting technology for sustainable agriculture in tropics

PurposeThe management of household wastes has been a real challenge for the capital city of Cameroon for some years now. In order to adopt ecological and sustainable strategies for better management of organic fraction of solid wastes, the present work was aimed to propose a sustainable alternative for the recycling of household organic waste through a vermicomposting process. Method A vermicomposting of household organic waste was carried out during 46 days, preceded by 23 days of pre-composting. Then, three treatments were established by mixing epigeic earthworms with different proportion of pre-composted waste. Maturation parameters such as pH, electrical conductivity (EC), C/N ratio, ammonium (N-NH4+) and total organic matter (TOM) were monitored about four weeks. The agronomic quality of the vermicompost was also determined at the end. Results During pre-composting, the temperature reached a maximum of 54.3±5.4°C suitable for the elimination of potential pathogen. The pH varied between 9.44 and 8.53 leading towards neutrality at the end of the vermicomposting process. The obtained mean values of C/N ratio and the TOM were respectively 11.04-11.68 and 25.82-27.19% in line with the AFNOR (NFU 44-051) guideline. The obtained vermicompost revealed high levels of nutrients such as N, P, K, Ca and Mg. The phytotoxicity test on lettuce showed germination rates above 50%, revealing the non-toxic nature of the vermicompost produced. Conclusion The vermicompost were rich in nutrients and exhibited the non-phytotoxicity. Thus, vermicomposting can be applied in the context of Cameroon to transform organic waste into organic fertiliser suitable for sustainable agriculture.

Design of a Community-Based Anaerobic Digester for Sustainable Solid Waste Management in Ile-Oluji Ondo State Nigeria

Aim: A Community-Based Anaerobic Digester was designed in this study for sustainable solid waste management in Ile-Oluji, Ondo state Nigeria.
 Methodology: Waste samples were collected from selected households for a period of one month and the components and percentage composition were determined. Afterwards, the physico-chemical characteristics of the substrate was investigated and the result used to design a community-based anaerobic digester.
 Results: The quantity, components and characteristics of waste generated was determined. The rate of waste generation was found to be 0.2kg/capita/day while the organic fraction of the total waste generated was found to be 55.7%. Physico-chemical characterization of the substrate was also investigated. The pH was found to be 6.36 ± 0.18, while the alkalinity 692.81 ± 78.62. The moisture content was found to be in the range of 71.20 ± 4.63%. Total solid was in the range 38.91 ± 5.25 while volatile solid was found to be 26.44 ± 2.83. carbon oxygen demand was found to be 834.33 ± 12.61, total phosphorus was in the range 4.20 ± 0.33. The Carbon on a dry weight basis was found to be in the range 60.41 ± 2.38, while nitrogen was found to be 4.79 ± 1.03. The C/N ration was found to be 21.61. The biogas yield ranged from 0 – 320 cm3 and 0 – 380cm3 per litre of substrate for biodegradable-only samples and biodegradable-cow dung samples respectively, for a forty days period of retention. The cylindrical dome type biogas digester was chosen for this study because of its simplicity in design and maintenance coupled with lower set up cost. The optimum volume of hydraulic chamber and gas storage chamber were designed to be the same as 850m3. Volume of fermentation chamber and sludge layer were calculated to be 2014m3 and 246m3 respectively, while the height and diameter of the fermentation chamber were 7m and 17m respectively.
 Conclusion: Anaerobic digestion of the biodegradable fraction of solid waste is a viable alternative that government and non-government organizations can key into for the improvement of public health especially in developing countries. The standardization of digester design parameters may pose challenges because of varying climatic conditions and complex socio-economic factors across different geographical contexts. Solutions may have to be adapted and localized to achieve a sustainable world.

SOLID WASTE MANAGEMENT PRACTICES IN BIKANER CITY, RAJASTHAN (INDIA)

Waste as one of the major environmental issues in the current world can be seen scattered ubiquitously. There is a dire need to properly manage the waste due to the negative effects on public and environmental health. The present study aims to do analysis of the solid waste management practices in Bikaner municipal area (Rajasthan). Solid waste samples were collected from 10 selected locations of the study area. Physical composition and physicochemical parameters of solid waste were determined. Physicochemical parameters such as pH, conductivity, total dissolved solids, salinity, moisture content and organic matter of solid waste were analyzed by using the standard methods. Organic matter made the highest content (27% to 76%) in the composition of all solid wastes. However, glass, metal and wood comprised the lowest content (1%). The pH range of samples was 5.1 to 7.5. Water holding capacity (%) was below 100 in all the samples though organic carbon ranged from 15.4 % to 19.6 %. Goga gate dumping site showed the highest solid waste content. It was found that waste management practices in Bikaner municipal area are not sustainable yet due to improper waste collection, waste dumping and lack of awareness among people. Solid waste need to be segregated at the source and segregation of recyclable waste should also be done for effective waste management. The organic fractions of solid waste could be utilized in composting.

Estimation of the Amount of Electrical Energy Available From the Biogas Produced at the Faecal Sludge Treatment Plant in the City of Sokodé

The purpose of this study is to estimate the amount of energy produced from biogas at the faecal sludge treatment plant in the city of Sokodé. The methodological approach consisted in producing biogas by co-digestion of faecal sludge with the fermentable fractions of solid waste then in estimating the quantity of energy available from the produced biogas. Tests of co-digestion of faecal sludge and fermentable fractions of solid waste, showed that from 2258 tons/DM of biomass in one year, 44476 m3 of biogas, or 29177 m3 of methane could be produced. The methane content, which is 65.6 %, is a very interesting source of energy. Several techniques for producing energy from biogas exist, one of which is the production of electricity. In this study, it is a question of making the choice of an adequate electric motor which will allow to produce electric energy from the biogas on the faecal sludge treatment plant. Thus, it was necessary to estimate the quantity of energy available from the biogas produced. To do so, it was calculated the quantity of energy that can be produced by the biogas in one year, the quantity of recoverable energy produced in a year and the quantity of energy supplied by biogas in one hour. The results showed that by 2035, the co-digestion of fermentable solid waste and faecal sludge from the city of Sokodé, would produce 534,246 kWh. The recoverable part would be 507,534 kWh and the energy supplied is 58 kWh.

Determination of Household Green Waste Fractions to Methane and its Economic Value

The methane gas produced at the landfills has become one of the main causes of the global warming. On the other hand, solid waste has potentials as a new energy. One of the well-known methods in processing solid waste into a new energy is methanation or anaerobic fermentation process. This paper considers calculation of the solid waste fraction of green waste that can be released as methane from traditional market. The gas volume is measured by using U-pipe filled with water. The difference of water height in the U-pipe is used to calculate the formed biogas volume used to calculate the weight fraction of the methane and amount of profit which can be generated from the solid waste processing by using anaerobic fermentation. The profits are obtained from the use of methane as the source of electricity energy and the profit of selling compost from the fermented trash residue. The results of this research show that the solid waste fraction which can be released as methane has the value range 0.11% - 0.18%, the benefits that can be generated from anaerobic process for organic solid waste are 300,899,290.00 IDR annually for electricity energy and 24,432,222,254.00 IDR annually for compost.

On the limits of empirical partition coefficients for modeling material recovery facility unit operations in municipal solid waste management

Material recovery facilities and mechanical biological treatments play an important role in current municipal solid waste systems, by providing a way to separate the different municipal solid waste fractions according to their main physical properties. However, the composition of their outputs streams is directly impacted by the composition of the input stream and by the sequence of unit operations considered, rending it particularly difficult to predict. Some authors have analyzed the sorting efficiency of the different unit operations commonly found in these processes and have derived partition coefficients. The main available coefficients were reviewed to identify the differences on both the methodological and numerical levels. Results showed large discrepancies for both cases amongst literature data but also with experimental data derived from an MRF plant located in Canada. A sensitivity analysis realized on a typical MRF plant showed the strong influence of the partition coefficient differences on the potential recovery of these plants. The trommel was identified as the unit operation having the largest impact on the modeling results. According to the sensitivity of the recovery of these kind of plants for each unit operation, a modeling approach is proposed for three groups of unit operations.

ACCURACY OF NONPARAMETRIC DENSITY ESTIMATION FOR UNIVARIATE GAUSSIAN MIXTURE MODELS: A COMPARATIVE STUDY

Flexible and reliable probability density estimation is fundamental in unsupervised learning and classification. Finite Gaussian mixture models are commonly used for this purpose. However, the parametric form of the distribution is not always known. In this case, non-parametric density estimation methods are used. Usually, these methods become computationally demanding as the number of components increases. In this paper, a comparative study of accuracy of some nonparametric density estimators is made by means of simulation. The following approaches have been considered: an adaptive bandwidth kernel estimator, a projection pursuit estimator, a logspline estimator, and a k-nearest neighbor estimator. It was concluded that data clustering as a pre-processing step improves the estimation of mixture densities. However, in case data does not have clearly defined clusters, the pre-preprocessing step does not give that much of advantage. The application of density estimators is illustrated using municipal solid waste data collected in Kaunas (Lithuania). The data distribution is similar (i.e., with kurtotic unimodal density) to the benchmark distribution introduced by Marron and Wand. Based on the homogeneity tests it can be concluded that distributions of the municipal solid waste fractions in Kutaisi (Georgia), Saint-Petersburg (Russia), and Boryspil (Ukraine) are statistically indifferent compared to the distribution of waste fractions in Kaunas. The distribution of waste data collected in Kaunas (Lithuania) follows the general observations introduced by Marron and Wand (i.e., has one mode and certain kurtosis).

Thermophilic Biogas Upgrading via ex Situ Addition of H2 and CO2 Using Codigested Feedstocks of Cow Manure and the Organic Fraction of Solid Municipal Waste.

Bioconversion of renewable H2 and waste CO2 using methanogenic archaea is a promising technology for obtaining high-purity CH4, which can serve as an alternative for natural gas. This process is known as ex situ biogas upgrading. This work highlights the pathway toward the bioconversion of renewable H2 and CO2 into high-purity biomethane by exploiting highly accessible agro-municipal residues: cow manure (CM) and the organic fraction of solid municipal waste (OFSMW), which used to be called “waste materials”. More specifically, an ex situ thermophilic (55 °C) biogas upgrading process was conducted by CM and OFSMW codigestion at different mass proportions: 100:0, 80:20, 70:30, 60:40, and 50:50. Maximum CH4 concentrations of 92–97 vol % and biogas volumetric production rates of 4954–6605 NmL/L.d were obtained from a batch reactor of 3 L working volume. Feedstock characterization, pH monitoring, and the carbon-to-nitrogen ratio were critical parameters to evaluate during biogas upgrading experiments. In this work, the usefulness of agro-municipal substrates is highlighted by producing high-purity biomethane—an energetic chemical to facilitate renewable energy conversion, which supports various end-use applications. This process therefore provides a solution to renewable energy storage challenges and future sustainable and green energy supply.

Optimal control of leachate recirculation for anaerobic processes in landfills

<p style='text-indent:20px;'>A mathematical model for the degradation of the organic fraction of solid waste in landfills, by means of an anaerobic bacterial population, is proposed. Additional phenomena, like hydrolysis of insoluble substrate and biomass decay, are taken into account. The evolution of the system is monitored by controlling the effects of leachate recirculation on the hydrolytic process. We investigate the optimal strategies to minimize substrate concentration and recirculation operation costs. Analytical and numerical results are presented and discussed for linear and quadratic cost functionals.

Effects of “soil‐like” particle size on gas transport and water retention properties in aged municipal solid waste from a Sri Lankan open dumpsite

AbstractOpen dumps constitute a major source of greenhouse gases (GHGs), predominantly methane and carbon dioxide, in developing countries. In an aged dump, typical waste composition is dominated by the “soil‐like” fraction of which physical, hydraulic and gas transport characteristics markedly affect GHG emissions. This study characterized soil‐gas diffusivity (Dp/D0), soil‐water characteristics (SWC), and particle size distribution in “soil‐like” fractions of aged solid waste retrieved at 2.5–5 m depth from an old open dumpsite situated at Kurunegala, Sri Lanka. The “soil‐like” fraction was proportioned into three groups based on particle size (0–4.75, 4.75–9.5, and 9.5–25 mm) to investigate the particle size effect on Dp/D0 and SWC. The simulated methane concentration profiles in different size groups were also examined using the transport simulator TOUGH2‐EOS7CA based on the multiphase flow of multicomponent gas mixture (methane, water vapour and air) under dry and half‐saturation conditions across a predefined temperature gradient. The results highlighted distinct two‐region characteristics (i.e., inter‐aggregate and intra‐aggregate pore regions) in all three size fractions which could be adequately parameterized with existing and modified bimodal functions. We proposed a useful practical tool for estimating Dp/D0 for known mean particle size and volumetric water content in the absence of direct measurements. The results further revealed that Dp/D0 is particle‐size dependent; however, Dp/D0 remained invariant across all size fractions at the volumetric water content of ∼0.22–0.25 cm3 cm−3. Numerical results further showed a pronounced effect of particle size and soil moisture on gas transport properties.