Fraction Of Solid Waste Research Articles

Metal Analysis of Leachate from the Organic Fraction of Urban Solid Waste (MSW) from the Municipality of Belém/PA

In this study, the analysis of metals in the solubilized extract of the organic fraction of Urban Solid Waste (MSW) from the municipality of Belém do Pará was carried out. The waste used in this research was collected in residential areas, through door-to-door collection, with the points and neighborhoods served in the municipality of Belém determined by the sectorization of these locations, with family income as the main parameter. The MSW was collected and transported to the segregation area. Gravimetric analysis of MSW was carried out and the selected organic and paper fractions were subjected to drying, crushing and sieving pre-treatment. Next, the solubilized extract of the organic fraction of MSW was obtained following the method set out in NBR nº 10.006/2004 of the Brazilian Association of Technical Standards. The values obtained were compared with CONAMA Resolutions n° 357/2005, 396/2008 and 430/2011, in addition to being compared with results of bibliographical research. The results indicated that these wastes do not comply with environmental and health regulations. Although a highly significant association was found between chromium and boron through Pearson’s correlation, the remaining strong correlations between other elements did not reach statistical significance. Furthermore, a similarity was observed in the solubilization conditions of these wastes with those found in landfill leachate.

Use of the Organic Fraction of Urban Solid Waste to Recover Degraded Areas in Chilca, Peru

Use of the Organic Fraction of Urban Solid Waste to Recover Degraded Areas in Chilca, Peru

Towards improved flexural behavior of plastic-based mortars: An experimental and modeling study on waste material incorporation

A considerable fraction of solid waste, which is harmful, chemically reactive, and infectious, is generated globally. The frequent deposition of these wastes in landfills has significant environmental and health consequences. This study aims to develop an environmentally conscious approach by incorporating finely ground waste materials, namely marble powder (MP), glass powder (GP), and silica fume (SF), into plastic waste (PW) based mortar to assess their efficacy in improving flexural strength (FS). Plastic waste mortar samples were cast using shredded PW, replacing sand in amounts ranging from 5 % to 25 %. The FS of these samples was measured after 28 days and used as a reference. MP, GP, and SF were individually incorporated into PW-based mortar formulations in varying quantities of 5–25 %, with increments of 5 %, by replacing cement. In PW-based mortar formulations, waste materials were also utilized in various combinations, including GP+SF, MP+SF, MP+GP, and MP+GP+SF. In addition, prediction models, including decision tree (DT) and artificial neural network (ANN), were constructed utilizing experimental data for the FS of PW-based mortar. The substitution of PW with sand reduces the FS of mortar samples. The research findings emphasize that optimal replacement levels for MP, GP, and SF in PW-based mortar mixtures, based on their ability to enhance FS, were 15 %, 10 %, and 15 % by cement mass, respectively. However, the cumulative incorporation of MP, GP, and SF in PW-based mortar suggests cement should not be replaced beyond 15 %, as it reduces the FS. Both prediction models exhibited a high degree of correlation with the coefficient of determination (R2) value of 0.925 for ANN and 0.959 for the DT model. The findings showed that MP, GP, and SF may be used in PW-based mortar to improve the FS while producing eco-friendly building material.

Migration of trace elements and radioisotopes to various fractions of solid wastes generated as a result of the sewage sludge incineration process

The research was aimed at providing new knowledge in the field of chemical characteristics of solid waste generated in the process of combustion of sewage sludge in fluidized bed furnaces. The research material consisted of disposed fluidized beds (DFB), sewage sludge ash (SSA) and air pollution control residues (APC) from three Polish installations for the thermal treatment of sewage sludge. Natural radionuclides as well as anthropogenic isotope 137Cs were determined in the tested materials and the migration of a wide spectrum of trace elements to various waste fractions generated in the process of sewage sludge combustion was examined. It was observed that both radioisotopes and most of the trace elements determined accumulate in SSA and DFB, while the APC fraction contains a much smaller amount of them. The exceptions are mercury and selenium, whose volatile compounds migrate to the exhaust gas dedusting system and accumulate in the APC fraction (up to 40 mg/kg and 13 mg/kg, respectively). A potential threat from the 226Ra isotope in SSA is identified in the context of the management of this waste in the production of building materials because the typical activity of 226Ra in SSA collected from areas with very low Ra content in natural environment exceeds 1.5–6 times the activity of this isotope in conventional cement mixtures. When managing SSA and DFB, special attention should be paid to the content of metalloids such as As, B and Se, due to the high content of mobile forms of these elements in the mentioned materials.

Evaluation of the Dark Fermentation Process as an Alternative for the Energy Valorization of the Organic Fraction of Municipal Solid Waste (OFMSW) for Bogotá, Colombia

In the context of valorizing the organic fraction of urban solid waste (OFMSW) in megacities, dark fermentation emerges as a central strategy alongside composting and anaerobic digestion. This article focuses on assessing the environmental, technical, and energy viability of dark fermentation using life cycle assessment (LCA) and circular economy principles. Dark fermentation for biohydrogen production is an active and promising research field in the quest for sustainable biofuels. In this context, defining operational parameters such as organic loading and the substrate-inoculum ratio is relevant for achieving better production yields. Laboratory tests were conducted using organic loading values of 5, 10, and 15 g of volatile solids per liter (gVS/L) and with substrate-inoculum ratios (s/x) of 1, 0.75, and 0.5 g of volatile solids of substrate per gram of volatile solids of inoculum (gVSs/gVSi). The combination with the best performance turned out to be an initial organic loading of 10 gVS/L and an s/x of 1 gVSs/gVSi. From this result, it was determined that the s/x had a greater impact on production. Finally, a valorization plant was dimensioned with the scaled-up process, starting from the municipal solid waste generated by Bogotá projected for 2042. The scaling was demonstrated to be energetically sustainable, producing a power of 2,368,358.72 kWh per day.

The misconception of soil organic carbon sequestration notion: When do we achieve climate benefit?

AbstractSoil organic carbon (SOC) sequestration is a key function of natural and semi‐natural ecosystems. Restoring this property in terrestrial ecosystems has become central to the EU's climate change mitigation and adaptation strategies. However, SOC sequestration is a widely misunderstood concept. The different methodological approaches used to investigate and compare SOC stock under sustainable agricultural practices play a key role in reinforcing misconceptions about this complex process. This commentary paper aimed not only to provide a clear definition of SOC sequestration, but also to interpret the results that can be obtained for SOC stock change estimation using the SOC stock difference and the paired comparison methods, as well as to identify the soil carbon‐related processes that achieve climate mitigation. SOC sequestration can be defined as the progressive increase in a site's SOC stock compared with pre‐intervention via a net depletion and transfer of atmospheric CO2 into the soil, where it is retained as soil organic matter (SOM), by plants, plant residues, or other organic solids such as the material derived from the organic fraction of farming solid waste, which can be used as a fertilizer (e.g., manure, compost, biochar, and digestate), and that is produced or derived from that land unit. To date, the most appropriate way to determine whether a land unit's soil is a sink or rather a source of atmospheric CO2 is to implement the SOC stock difference method, provided the non‐occurrence of carbon exchange between ecosystems.

Grinding and Pelleting Characteristics of Municipal Solid Waste Fractions

The efficient utilization of low-cost carbon feedstocks, such as municipal solid waste (MSW), in biorefineries has become increasingly important for reducing GHG emissions and meeting the growing demand for renewable energy sources. However, MSW as a feedstock presents several challenges, including high moisture content, compositional variability, particle size and shape, density, and ash content. To address these challenges, the potential of mechanical dewatering and high-moisture pelleting processes for densifying MSW fractions, such as paper, cardboard, thin plastic, and thick plastic, into low-cost carbon feedstocks with improved handling and conversion properties were investigated. The effect of these preprocessing technologies on the critical quality attributes (CQAs) of the resulting pellets, including bulk density, durability, and size uniformity, were evaluated. The results showed that with these preprocessing technologies, the paper and cardboard fractions could be pelleted at moisture contents over 40% (w.b.) while achieving >99% durability and >300 kg/m3, while the high moisture plastic fractions were not suitable for pelleting. The thick plastic fraction processed in a screw press was shown to remove up to 30% of the moisture content in a single pass. These findings suggest that these mechanical preprocessing technologies can improve the physical properties of low-cost municipal solid waste fractions for biofuels production.

Hybrid methodology for the characterization and revalorization of the organic fraction of waste generated in a Mayan community

Low-income rural communities suffer from a lack of quality and availability of services that impact their quality of life, such as sanitation facilities or solid waste collection. From an engineering perspective, it is possible to develop solutions that comprehensively address these needs. Domestic biodigesters are a convenient method to dispose of the organic fraction of solid waste; they can function as safely managed sanitary facilities and return useful products to the community such as cooking gas and organic fertilizer. However, successful implementation requires designing a solution according to the needs and resources of each community. The objective of this research was to develop a methodology for the characterization of organic waste generated in a Mayan community located in Yaxuná, Yaxcabá, Yucatán, and to revalorize it through its co-digestion with human excreta in domestic biodigesters. The proposed hybrid methodology (the extended application of questionnaires combined with the physical inspection of a small sample) was able to detect general patterns in the generation of organic wastes that were subsequently analyzed to select those wastes that, due to their characteristics (statistical and physicochemical), can enter the anaerobic digestion process in combination with human excreta. Finally, a mixture of substrates was proposed according to the particularities of Yaxuná. It was estimated that methane production from this mixture would be 53.36 L per person per day.

Prediction of Leachate Characteristics via an Analysis of the Solubilized Extract of the Organic Fraction of Domestic Solid Waste from the Municipality of Belém, PA

This work aimed to predict the physical–chemical characteristics of leachate according to the analysis of the solubilized extract from urban household solid waste (UHSW), on a laboratory scale, in the city of Belém/PA, Brazil. The neighborhoods where the waste was collected were sectorized based on geographic and socioeconomic data, with family income as the main parameter. After collection, the material was sent to the segregation area, where a gravimetric analysis of the UHSW was performed and fractions (paper, cardboard, Tetra Pak, rigid plastic, malleable plastic, metals, glass, organic matter, sanitary waste, fabrics and rejects) were segregated. After the gravimetric characterization, it was found that the highest average proportions were 55.57% organic matter, 14.26% sanitary waste and 9.97% malleable plastic. The organic fraction was selected and subjected to drying, crushing, sieving and packaging pretreatment, and then the solubilized extract of this fraction was obtained according to NBR No. 10.006/2004 of the Brazilian Association of Technical Standards. In the analyses of the solubilized extract, values for total nitrogen (201.80 to 359.90 mg·L−1), ammonia nitrogen (161 to 289 mg·L−1), nitrate (10 to 40 mg·L−1) and chemical oxygen demand were obtained (28,701 mg·L−1 to 38,608 mg·L−1), indicating the similarity of the waste solubilization conditions to those of leachate from landfills, in addition to being in noncompliance with environmental and health legislation, thus making it necessary to have an efficient waste management system, which avoids the release of waste into the environment that would result in environmental impacts similar to those of leachate contact with the environment.

Changes in the prokaryotic communities occurring along a two-stage anaerobic digestion system treating the organic fraction of solid waste

Two-stage anaerobic digestion is useful for recycling of the organic fraction of municipal solid waste and wastewater; the prokaryotic communities involved in this process were characterized using massive sequencing of 16S rRNA gene amplicons. During the 60-day study the prokaryotic communities were stable in time but were affected by their position in the system. The first stage of solid waste digestion was operated in an anaerobic-hydrolytic leach bead reactor with high organic solids content, the microbial communities were dominated by members of the orders Bacteroidales (62%), Selenomonadales (15%), Lactobacillales (13%), Clostridiales (4%) and Rhodospirillales (1%). At this stage, a vertical stratification acted as a transition zone from aerobic to anaerobic environments modifying significantly the composition and structure of bacterial communities.The second stage occurred in an up-flow anaerobic sludge bed reactor specialized in acidogenesis-methanogenesis, where the leachate of the first stage was co-fed with municipal wastewater. In this stage, the bacterial community was dominated by members of the orders Pseudomonadales, Clostridiales, Burkholderiales, Bacteroidales and Syntrophobacterales (accounting for 52%), while the most abundant orders of the archaeal community corresponded to Methanosarcinales (72%) and Methanobacteriales (13%), both of them with methanogenic capacity.

Study on the Performance and Solidification Mechanism of Multi-Source Solid-Waste-Based Soft Soil Solidification Materials

In this paper, ground granulated blast furnace slag, steel slag, red mud, waste ceramic powder, and desulfurization gypsum were used as raw materials to develop a kind of multi-source solid-waste-based soft soil solidification material. Three ratios and the strength activity index were used to determine the fractions of different solid wastes. The mineralogical and microstructural characterization was analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM), and thermogravimetric analysis–differential scanning calorimetry (TG&DSC) tests. The results showed that the unconfined compressive strength of the three types of soft soil increases with an increase in the content of the solidifying agent. The failure strain of the stabilized soil decreases from 1.0–1.3% to 0.75–1.0%, and the failure mode gradually changes from plastic failure to brittle failure. The optimum content of the solidifying agent was determined to be 17% (the lime saturation factor (KH), silica modulus (SM), and alumina modulus (IM) of the solidifying agent were set to 0.68, 1.74, and 1.70, respectively), and the unconfined compressive strength (28 d) of the solidified soil (sandy soil, silty clay, and organic clay) was 3.16 MPa, 2.05 MPa, 1.04 MPa, respectively. Both measurements can satisfy the technical requirements for a cement–soil mixing pile, suggesting the possibility of using various types of solid waste as a substitute for cement.

Characterization of municipal solid waste: Measures towards management strategies using statistical analysis

Implementing unified municipal solid waste management (MSWM) is often difficult due to socio-economic variables. However, spatial GIS models and statistical analysis of solid waste characterized by the weekdays, weekends, and festivals can somewhat mitigate the variance and assist with selecting suitable waste management methods. This paper presents the example of Rajouri, India, to propose a suitable MSWM based on Inverse Distance Weighted (IDW) intensity maps and statistical findings. The considered region was divided into different sample sites based on the local population density, and Municipal Solid Waste (MSW) was collected from four locations in each site on weekdays, weekends, and festivals. Compositional analysis of the MSW was then used to generate spatial IDW models in QGIS 3.22.7 to interpolate MSW generation over the entire area. Finally, statistical analysis was conducted to gain insight into the waste generation and accumulation trends. The results show that Rajouri produces 245 tonnes of waste daily (per capita: 0.382 kg/day) with a large organic fraction compared to other waste categories. Besides, waste generation is observed to increase over weekends and festivals due to increased consumption of material goods. Composting could serve as a vector for municipal solid waste because of its increased organic component and cost constraints. However, further research on the potential segregation techniques for the organic fraction of solid waste is needed.

Санітарно-епідеміологічна оцінка проєктних рішень щодо сучасного поводження з твердими побутовими відходами

Objective: sanitary and hygienic assessment of the project of a complex for processing and disposal of solid waste. In context, tasks of determining predictive indicators of environmental impact and establishing the hazard category of RDF fuel from sorted fractions of municipal solid waste with the possibility of its further use as an alternative fuel were solved. Materials and methods. Objects - the designed parameters of the arrangement of the object for the treatment of solid waste, indicators of alternative fuel from combustible fractions of solid waste and the conditions for the further operation of the object. RDF fuel from MSW fractions was evaluated in terms of physicochemical and toxicological parameters with laboratory tests and calculation of hazard category. The assessment of operating conditions of facility was carried out by the method of hygienic analysis, taking into account the specifics of impact on the environment. Results. A modern complex for the processing and disposal of solid waste as part of a waste sorting and landfill for the non-utilizable part of solid waste is planned to be located outside the boundaries of the settlement. Arrangement of the landfill is provided in accordance with construction and environmental standards. From combustible fractions of sorted waste, it is planned to produce RDF fuel. Studies have established the main indicators of fuel. According to results of acute toxicity assessment and calculated coefficients, the waste mixture in composition of RDF fuel belongs to the 4th category of waste and 4th class in terms of acute toxicity in accordance with the requirements of the EU Regulations. Combustion of this fuel in whirlpool kilns of cement plants is optimal solution, since safety conditions are observed in accordance with requirements of EU Directive for combustion at a temperature of at least 850 ◦C for a duration of at least 2 seconds. The sanitary and hygienic assessment of probabilistic impact of the object was made on the basis of predictive calculated indicators, which indicate the absence of excess impact and determine the 300 m area of its distribution, which is less than 500 m of the standard size of the sanitary protection zone. Conclusions. It has been established that the planned sorting activities with the removal of recyclable materials and the disposal of non-utilizable part of MSW make it possible to further use the useful part of waste, reduce volume and area of disposal, and extend the life of landfill. Design solutions for arrangement of a modern complex for processing and disposal of solid waste, according to the predictive assessment, will not have an excess impact on the environment, will ensure environmental safety in the area of probable impact of the facility and comply with domestic and European standards. Production of RDF fuel to specifications and further use as an alternative fuel for whirlpool kilns in cement plants is in line with the Basel Convention, the Glasgow UN Framework Convention on Climate Change and will contribute to environmentally sound waste disposal in accordance with EU Directive 2010/75 /EU. Arrangement of a modern facility for the treatment of solid waste will create appropriate living conditions for the population and compliance with the sanitary and epidemiological safety of settlements’ territories of in service area.

Fungal pretreatment of citrus waste improves the hydrolysis and acidogenesis of the organic fraction of urban solids wastes

This work shows the increase in hydrolysis and acidogenesis of the organic fraction of urban solid waste (OFUSW) by the action of fungal hydrolytic enzymes obtained by solid-state fermentation (SSF) with Aspergillus niger C25B28 on citrus wastes (CW) without sterilization or the addition of nutrients. To quantify the hydrolysis and acidogenesis of the organic fraction of urban solid waste, three treatments were studied in triplicate: OFUSW plus 10 % fresh CW (RC treatment), and OFUSW plus 10 % citrus wastes pretreated by SSF (RCA treatment). The mixtures were packed into an anaerobic hydrolytic leaching bed reactor. The results showed that SSF decreased the limonene concentration by 97 %, removing 20 % of fiber and 46 % of fat from fresh CW. Pectinases (37 U/g DM [dry matter]), cellulases (33 U/g DM), xylanases (98 U/gDM), and proteases (0.2 U/gDM) were produced. Significant differences were observed between the different treatments: the greatest reduction in total solids (24 %), the highest removal efficiency of organic matter as chemical oxygen demand (COD), and the reduction of fats (23 % and 28 %, respectively), was achieved in RCA, compared to those obtained in the reactors with OFUSW and ReC without pretreatment. The production rate of volatile fatty acids (VFA) was 1.4 gVFA/Ld for RCA, 4.5 times higher than in the reactors without pretreatment.

Systematic Review and Meta-Analysis on the Use of LCA to Assess the Environmental Impacts of the Composting Process

Following the industrial revolution, major economic and populational growth took place, and, therefore, solid waste generation increased exponentially. Nowadays, waste management still generates major impacts because the current wide offer of waste management strategies includes many solutions that produce suboptimal results, such as landfill or waste incineration. From a circular economy perspective, composting is a potentially sustainable option to treat the organic fraction of solid waste and has the advantage of recycling many organic compounds that can be reintroduced into the natural processes. This study aimed to provide a meta-analysis using the Life Cycle Assessment (LCA) method to evaluate the impacts of composting by performing a systematic literature review of the diversity of approaches and assessing environmental impacts. The results of the impact assessment were highly dependent on the choices made over the system boundary and the functional units. The most cited environmental impacts were Global Warming Potential, Acidification Potential, Eutrophication Potential, Photochemical Oxidation Potential, and Ozone Layer Depletion, as gaseous emissions from the transport and decomposition represent the main contributors to these categories. Using a smaller dataset and evaluating the use of the CML method and the most cited impacts categories, it was found that In-vessel Composting and Home Composting were considered the best environmental options among the studied composting methods. Composting environmental impacts were also highly related to the use of non-renewable energy sources, which puts composting at a disadvantage when compared with the use of anaerobic digestion. Such results emphasize the benefits of using these waste management technologies as complementary instead of substitutes.

A Preliminary Assessment of Utilizing Solid Waste Fractions as an Agricultural Growth Medium in Arid Soils

The fast-paced and globalized industrial/population growth has generated a vast consumerism-based culture, resulting in the rapid increase in municipal solid waste generation. Considering the case of Kuwait, the collection and disposal of waste has become a major economic and health issue for both the general public and the Kuwaiti government. Addressing and improving current waste disposal challenges, through utilizing (or recovering) basic materials from waste, will benefit society in terms of reductions in costs, pollution and associated negative health impact. The objective of this study was to assess the re-utilization prospects of waste materials (paper, cardboard and cotton) as a substrate for plant growth, consequently serving as a growing medium material, apart from naturally occurring soil. This investigation was conducted across two land plots in the Wafra region, located in Southern Kuwait. The plots were planted with Rhanterium epapposum and Festuca rubra seeds. Temperature, humidity and growth rates were measured during this study. Study results indicated that chemical composition of the growth medium is suitable for local conditions. Furthermore, the soil plot with added growth medium was found to retain moisture for prolonged periods in comparison to the plot lacking in growth medium. Field studies on grass germination and growth rates highlighted that waste-derived substrate is favorable to their development and adaptation within challenging environmental conditions. This investigation can play an important part for introducing and developing the concept of a circular economy within Kuwait, with potential to improve waste management within the country.

Solid Waste Management in Rural Communities of Developing Countries: An Overview of Challenges and Opportunities

Solid waste management (SWM) in rural areas of many low- and middle-income countries (LMICs) represents a critical and underrated topic. However, almost half of the world’s population still lives in rural areas and an adequate SWM is crucial in reducing environmental and health threats. A lack of knowledge and appropriate tools often leads to inappropriate practices such as waste dumping and uncontrolled burning. However, appropriate methods can transform waste into resources and even guarantee a revenue source. This manuscript provides an overview of the state of the knowledge characterising SWM in rural communities of LMICs, analysing common practices and principal issues. Different solid waste fractions are considered. Virtuous approaches are presented, taking into account recent sustainable solutions. Considering that a relevant part of the world population is still living in rural areas, the benefits associated with an appropriate SWM may be enormous. Such activities may improve local conditions from social, environmental and health perspectives; furthermore, they may have a global impact on facing climate change and environmental pollution.

Managing the Organic Municipal Waste in Palestine: Linking Policy, Practice and Stakeholders’ Attitude Towards Composting

Local authorities in Palestine are the service providers for solid waste management. Given that the organic fraction is the largest in municipal solid waste, and with ineffective management policies, the study of attitudes and behavioral aspects of personnel involved are very-important parameters in developing an effective waste management system and assisting policymakers in rectifying these policies. This study aims to assess the attitude of local authorities (LAs) in the southern West Bank of Palestine towards organic municipal solid waste composting and the factors that affect their attitude. The data was gathered via a structured questionnaire from all local authorities in the study area. The results showed that the local authorities’ attitude towards organic solid waste composting is low and can be considered dissatisfactory since only 36.5% of the local authorities are planning for composting compared to 63.5% who are not. The results also showed that municipal solid waste composting is significantly affected by nine factors, including financial capacity, proper machinery, enough refuse collection vehicles to collect solid waste fractions separately, availability of area of land to be used for composting, familiarity with composting systems, staff previous-experience in compost production, acceptance of the rapid composting system, staff training in compost production, and believe that solid waste composting is within the LAs’ responsibility. Implications municipal solid waste is growing continuously due to the population growth, increase methane emissions, and add more pressure on the landfills, which faces political and social restrictions for expansion in Palestine. In addition, there is severe restrictions on the import of chemical fertilizers imposed by Israel. Therefore, composting the organic fractions of solid waste can, to a large extent, extend the life of the landfills and compensate the shortage of fertilizers in the market, encourage organic farming and reduce methane emissions as well. Moreover, it can contribute to achieve the objective of the national strategy on solid waste management.

Anaerobic co-digestion of food waste with sewage sludge from wastewater treatment plant of Sequele, Luanda-Angola

This work aimed to evaluate the potential for methane production from anaerobic co-digestion of the organic fraction of urban solid wastes with sewage sludge. The tests were carried out using Bioprocess AMPTS II batch reactors operated at 37 °C in two different runs. In each run, a different food waste sample, inoculated with sludge, was tested varying the inoculum to substrate ratio (ISR) in each reactor. The experimental cumulative methane production by the mixture at the end of the tests was compared with the expected methane production in order to identify synergistic effects. The modified Gompertz model was fitted to experimental substrate cumulative methane yields. The results of this study suggest the suitability of this model to describe the degradation kinetics. ISR was found to be an important parameter for an efficient methane production, values ≥ 2 are recommended in order to prevent the pH drop in reactors. For one of the food waste samples, the highest substrate methane yield achieved was 91% of the theoretical value. For the other one, synergistic effects were observed in the mixtures of inoculum and substrate, that were attributed to an enhanced methane production by the sewage sludge when mixed with the food waste. The anaerobic co-digestion of food waste with sewage sludge from the Sequele WWTP is a sustainable treatment option for both organic wastes, which can be implemented in this WWTP where the sludge is simply discarded after dehydration.

Utilization and life cycle assessment of low activity solid waste as cementitious materials: A case study of titanium slag and granulated blast furnace slag

The dumping of cement production and industrial solid waste can cause severe environmental impact. In order to reduce the environmental impact of cement production and reasonably dispose of solid waste, a new type of cementing material was developed using industrial solid waste as raw materials. It solves the problem that low activity solid waste is difficult to reuse and makes up for the less research, which considered both preparation and environmental evaluation. The orthogonal tests of cement mortar strength as well as life cycle assessment were carried out. The results from variance and range analyses of the orthogonal tests revealed that the fraction of solid waste mainly affected the compressive strength of the solid waste cement mortar, and its specific surface area primarily influenced the flexural strength. After curing for 28 days, the compressive and flexural strength values of the developed cementing material were 40.6 MPa and 8.6 MPa, respectively. The results of life cycle impact assessment indicated that the developed solid waste cement had more environmental advantages than ordinary cement in 18 midpoints environmental impact types, and could diminish environmental impact by 16.1 % on the whole. The solid waste cement has achieved great environmental gains in the human toxicity, natural land transformation, metal depletion, climate change and other environmental impact categories. In addition, the clinker calcination, transportation and material mining were identified as critical processes responsible for the human toxicity, natural land transformation and metal depletion. Through sensitivity and uncertainty analyses, the development of the solid waste cement was proved to be the most effective method to decrease the environmental impact of cement. Finally, the methods of further reducing the environmental impact of cement were proposed.