Organic Municipal Solid Waste Research Articles

Conversion of Lignocellulosic Wastes into Biofertilizer using Bacterial Consortium

Lignocellulosic biomass abundantly and ubiquitously occupies the earth. However, their complex molecular structure prevents their use as a source of organic material for fermentable sugars and nutrients to be used as foods, fertilizers and biofuels. For an efficient carbon cycle, microbial enzymes play a key role in slow biodegradation of lignocellulosic wastes in nature. Microbiological applications can enhance the rate of biodegradation to utilize agro-industrial and organic municipal solid wastes, containing up to 50% lignocellulose substrates, as an inexpensive and sustainable source of plant nutrients. With this hypothesis, the current study was carried out to prepare a consortium of lignocellulose degrading bacteria and use it to convert lignocellulosic substrates in garden, sugarcane, rice, cotton and fruit waste into biofertilizer. Overall, 7-14% reduction in cellulose and 3-6% reduction in lignin content, along with decrease in pH was observed on treatment of above wastes with microbial consortium in 42 days. In spite of the low conversion rates observed in our study, better root, shoot as well as leaf development was observed in moong seedlings grown in soil amended with biofertilizer (3:1 ratio) as compared to controls. Another interesting observation was the biofertilizers with low pH prepared from sugarcane wastes (pH 3.1) and fruit wastes (pH 3.6) supported plant growth more efficiently as compared to other biofertilizers (pH 5.0 to 5.7). Thus, in addition to feasible conversion of lignocellulosic wastes into biofertilizer, our study further suggests the use of selective wastes as raw material depending on the preference of plants for slightly acidic to neutral soil pH for growth.

Municipal Organic Solid Waste to Energy: A Case Study of the West Bank-Palestine

Organic solid waste represents 50% of the Municipal Solid Waste (MSW) composition in Palestine. MSW in the West Bank (WB) are managed by municipalities, Local Governmental Units (LGUs), and Joint Service Councils (JSCs). MSW are collected and transferred to the existing four landfills along the WB, there are no waste separation or recycling in Palestine except small projects and enterprises. The collected MSW reaches the landfills as a mixed wastes with the composition of metal, paper, glass, plastic, and organic wastes. The current organic waste treatment in Palestinian territories is represented by composting and biogas generation, the small pilot projects of composting that have been implemented facing problems related to quality, competition, and financing. Biogas production from organic solid wastes is also limited and concentrated in producing biogas from animals manure. New proposals have been discussed regarding solid waste incineration in the field of Waste To Energy (WTE) projects, except the composting and bioenergy there are no another treatment for organic MSW in the WB. This study ensures about the importance of the concept of waste separation at source, and to adapt the concept of WTE operations. Due to the high moisture content and high organic proportion in the MSW; bio-drying processes are valuable as a pretreatment stage for organic waste treatment. This study also highlights on the Refuse Derive Fuel (RDF) as a product of bio-drying processes that could help in organic MSW treatment.

Medium chain length polyhydroxyalkanoate produced from ethanol by Pseudomonas putida grown in liquid obtained from acidogenic digestion of organic municipal solid waste

Production of medium chain length polyhydroxyalkanoate (mcl-PHA) up to about 6 g.L−1 was obtained by feeding ethanol to Pseudomonas putida growing in liquid obtained from acidogenic digestion of organic municipal solid waste. Washing the wet, heat-inactivated Pseudomonas cells at the end of the fermentation with ethanol obviated the need of drying the biomass and enabled the removal of contaminating lipids before solvent-mediated extraction of PHA. Using ‘green’ solvents, 90 to near 100% of the mcl-PHA was extracted and purities of 71–78% mcl-PHA were reached already by centrifugation and decantation without further filtration for biomass removal. The mcl-PHA produced in this way consists of 10–18% C8, 72–78% C10 and 8–12% C12 chains (entirely medium chain length), has a crystallinity and melting temperature of ∼13% and ∼49 °C, respectively, and is a stiff rubberlike, colourless material at room temperature.

Supplemental Sewage Scum and Organic Municipal Solid Waste Addition to the Anaerobic Digestion of Thickened Waste Activated Sludge: Biomethane Potential and Microbiome Analysis

Sewage scum (SS) is collected from sedimentation tanks in wastewater treatment plants (WWTPs). Despite its huge biogas potential, there is limited information on its potential as a co-substrate and microbial ecology, especially during anaerobic co-digestion (ACo-D) of the organic fraction of municipal solid waste (OFMSW) and thickened waste activated sludge (TWAS). In this biomethane potential (BMP) study, the bioenergy yield achieved by the supplemental addition of SS and OFMSW to TWAS was investigated, along with the microbial ecology. Compared with the digestion of TWAS alone, which produced 184.6 mLCH4 gVS−1, biomethane yield was enhanced by as much as 32.4–121.6% in trinary mixtures with SS and OFMSW, mainly due to the positive synergistic effect. Furthermore, a mixture of 40%SS + 10%TWAS + 50%OFMSW produced the highest biogas yield of 407 mLCH4 gVS−1, which is proof that existing WWTPs can produce additional energy by incorporating external bioresources, thereby reducing greenhouse gas emissions. Modified Gompertz and logistic function estimates showed that methane production rate improved by as much as 60% in a trinary mixture compared with the digestion of TWAS alone. The genus Methanosaeta, capable of generating methane by the acetoclastic methanogenic pathway among all the archaeal communities, was the most prominent, followed by hydrogenotrophic methanogen Methanospirillum.

Copyrolysis of Waste Cartons and Polyolefin Plastics under Microwave Heating and Characterization of the Products.

Municipal organic solid waste contains many recoverable resources, including biomass materials and plastics. The high oxygen content and strong acidity of bio-oil limit its application in the energy field, and the oil quality is mainly improved by copyrolysis of biomass with plastics. Therefore, in this paper, a copyrolysis method was utilized to treat solid waste, namely, common waste cartons and waste plastic bottles (polypropylene (PP) and polyethylene (PE)) as raw materials. The products were analyzed by Fourier transform infrared (FT-IR) spectroscopy, elemental analysis, GC, and GC/MS to investigate the reaction pattern of the copyrolysis. The results show that the addition of plastics can reduce the residue content by about 3%, and the copyrolysis at 450 °C can increase the liquid yield by 3.78%. Compared with single waste carton pyrolysis, no new product appeared in the copyrolysis liquid products but the oxygen content of the liquid decreased from 65% to less than 8%. The content of CO2 and CO in the copyrolysis gas product is 5-15% higher than the theoretical value; the O content of the solid products increased by about 5%. This indicates that waste plastics can promote the formation of l-glucose and small molecules aldehydes and ketones by providing H radicals and reduce the oxygen content in liquids. Thus, copyrolysis improves the reaction depth and product quality of waste cartons, which provides a certain theoretical reference for the industrial application of solid waste copyrolysis.

Bioenergy, Electricity, Biogas Production, and Emission Reduction Using the Anaerobic Digestion of Organic Municipal Solid Waste in Campinas, One of the Largest Brazilian Cities

Anaerobic digestion (AD) is an attractive process for bioenergy production and is considered to be an alternative way to reduce landfills. AD improves municipal solid waste (MSW) management, representing a profitable application of the circular economy and could reduce environmental impact. The methane (CH4) potential of four different organic fractions of MSW—paper (PFW), garden (GFW), food (FFW), and a mixture of these three (OFMSW)—via AD was used to investigate the energy potential and the economic and environmental impact of Campinas. Theoretical and experimental biochemical methane potential (BMP) and substrate biodegradability were determined using the Buswell and Müller equation and the VDI 4630 method. The Gompertz model was used to predict the kinetics of the biochemical processes. The highest experimental BMP (410.7 NmLCH4 gVS−1) and biodegradability (86.6%) were reached with OFMSW. OFMSW can avail an energetic potential of approximately 119 GWh year−1, with a biomethane production equivalent to diesel at 49.9 × 103 m3 year−1, hence, potentially curtailing the CO2 emissions of heavy-duty vehicles by almost 133 kt year−1. The electricity demand for approximately 11% of the households in Campinas could be met by the biogas produced by OFMSW, thus increasing local energy security. The replacement of fossil diesel with biomethane to fuel garbage trucks in Campinas could reduce 25% of the diesel demand.

Characterization of an endo-beta-1,4 glucanase gene from paper-degrading and denim bio-stoning cellulase producing Aspergillus isolates.

Cellulases are used in textile, pulp and paper, brewery and wine, sugars, and ethanol industries. Four fungal isolates obtained from organic municipal solid wastes (OMSW) were selected based on their cellulolytic activity on carboxymethyl cellulose (CMC) agar medium. Based on the internal transcribed spacer (ITS) sequence of the ribosomal DNA, the four cellulolytic isolates were identified as Aspergillus fumigatus AKAL1, Aspergillus oryzae AKAL4, Aspergillus flavus AKAL8, and Aspergillus flavus AKAL9. After 9 days of fermentation at 30°C and pH 6.5 under 110rpm agitation, these isolates produced the maximum amount of cellulase. The cellulase showed optimum activity at temperature 35-40°C and pH 6.0-7.0 and was stable for 1h at 25-45°C and pH 5.0-7.0. The Mg2+ and Zn2+ significantly increased but Hg2+ , K+ , and Ca2+ severely repressed the cellulase activity. Degradation of filter papers and bio-stoning of denim was successfully done with the crude cellulase. An endo-β-1,4-glucanase was isolated and characterized from Aspergillus isolates. Genome-wide analysis revealed that the genomes of A. oryzae, A. fumigatus, and A. flavus, the pertinent species of the fungal isolates, had 23, 25, and 22 cellulase genes, respectively. Phylogenetic analysis revealed that the cellulases in these fungal species were divided into three major groups, and the isolated endo-β-1,4-glucanase clustered to Group II. Ten different motifs are present in cellulases of the three species. Results herein provide a valuable resource for understanding cellulase genes in Aspergillus species and potential application of cellulase in textile and fermentable sugars production industries.

Anaerobic co-digestion of municipal organic solid waste: Achievements and perspective

One of the biggest problems that people confront in the 21st century is energy insecurity and global climate change. Carbon-neutral technologies are becoming more essential to fulfill global energy demands. The biochemical method used by anaerobic digestion (AD) process to produce biogas could transform complex municipal organic solid waste (MOSW) into a clean, sustainable energy source. In recent studies of AD, anaerobic co-digestion (AcoD) has gained widespread attention since it often produces a higher biogas yield than single-substrate digestion. This manuscript closes such gap by identifying the drawbacks of single substrate digestion associated with system optimization and feedstock properties as well as carefully analyzing the advantages of AcoD. Additionally, this article reviews the microbial population composition, synergistic impact of various co-feedstocks, and methane forecasting using several mathematical models. The limitations and potential outcomes of producing methane from MOSW are also addressed to enhance the effectiveness of the AcoD process.

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.

Composting from organic municipal solid waste: a sustainable tool for the environment and to improve grape quality

AbstractComposting from organic municipal solid waste (MSW), such as a separate waste collection, is a valid tool for eliminating a considerable amount of waste that would otherwise be destined for landfills and incinerators, thus representing an effective complement to traditional forms of recycling. It allows organic substance to be recovered and reintegrated into the soil, thus preventing erosion phenomena, increasing the biological fertility of the soil and contributing significantly to the restoration of impoverished sites. Modern winegrowing must address the issue of vineyard fertility in the sustainability context. The goal of this study was to assess the advantages of distributing a sustainable product to the vineyard that can achieve vine balance (vegetative and productive equilibrium). In a Vitis vinifera L. Sangiovese cv., vineyard, four soil treatments were applied (three compost rates and a control): municipal solid waste compost (40 tons per hectare – MSW40, 15 tons per hectare – MSW15, 2.5 tons per hectare – MSW2.5), and no compost (CTRL). The vine physiology (leaf gas exchange and water potential) and berry compositions (phenolic and technological maturity) were studied during the 2018–2019 growing seasons in the Sieci area, Italy. The results of this experiment provide some general insights showing that MSW compost options can be expected to reduce water stress, balanced vine performance and provide sustainable recirculation of organic matter. MSW compost is a true agronomic and environmental resource.

Torrefaction of organic municipal solid waste to high calorific value solid fuel using batch reactor with helical screw induced rotation

The potential of producing high calorific value (CV) solid fuel was investigated in a helical screw rotation-induced (HSRI) fluidized bed reactor based on mechanical fluidization. The study revealed that the HSRI torrefaction improved the torrefied product properties. For the 40 and 0 rpm conditions, the CV, fixed carbon, and ash contents of torrefied solid fuel increased with an increase in temperature. In contrast, volatile matter, moisture content, mass and energy yields decreased. The CV of torrefied solid fuel increased by a factor of 1.43 and 1.58 at 280 °C for the 40 and 0 rpm conditions, respectively. HSRI torrefaction enhanced the removal of hydroxyl functional group. HSRI torrefaction improved the hydrophobicity of the torrefied solid fuel. Therefore, the HSRI fluidized bed reactor promotes uniform temperature distribution, a higher heat transfer rate within the sample particles in the reactor, and a homogenous torrefied solid product compared to the fixed bed reactor.

Future Perspective for Utilization of Municipal Solid Waste (MSW) in India: A Review

Presently urban areas are reported for supporting 56% of the total world population, accountable for generating significant amount of municipal solid waste (MSW). Seventy percent of which ends into landfills, 19% is recycled and 11% is employed for energy generation. Generation of municipal solid waste in India is increasing day by day. The average per capita generation of waste was about 500 g/day in 2007 and it will increase to 925 g/day by 2047. Municipal solid waste (MSW) is one of the key components of India’s prominent mission ‘Swachh Bharat Abhiyan’. Rising urbanization, faster economic growth and lifestyle changes all contribute to higher waste generation in India. Unscientific treatment, improper collection and low use of technology based solutions for handling MSW lead to hazards like environmental degradation, water pollution, air pollution and soil pollution. The most important step to be used for management of this waste would be minimising its generation but this is not really possible. Then to manage waste sustainably, the waste to wealth route remains a viable solution although in India it is not common practice. Maximum recycling, composting with organic municipal solid waste and waste to energy generation should be utilised for MSW management. This approach of sustainable waste management can solve the problem of land required for waste disposal and resulting pollution problems of air, ground, surface water, soil etc.

Determination of the biochemical methane potential of food waste after aerobic storage and aeration pretreatment

AbstractFood waste represents a relevant fraction of municipal solid organic waste, and anaerobic digestion can be an eco‐friendly alternative for sustainable management in a circular economy framework. One of the challenges to the implementation of anaerobic digestion is the availability of easily degradable compounds in the substrate, which can be solved by the application of pretreatment to increase methane production. In this study, the influence of aerobic storage time and forced continuous aeration pretreatment on the biochemical methane potential of food waste was evaluated. The results demonstrate an increase in the methane production concerning the total volatile solids (TVS) of food waste stored for 7 days (425 NmL CH4 g−1 TVS) compared with fresh samples without pretreatment (375 NmL CH4 g−1 TVS). The adoption of forced and continuous aeration pretreatment on food waste for 4 days produced 456 NmL CH4 g−1 TVS for the leachate, 1.22‐fold higher than that for the food waste without storage. In conclusion, the application of aeration pretreatment previous to anaerobic digestion can be an alternative to increase the methane potential from food waste. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd.

Can the biological stage of a mechanical–biological treatment plant that is designed for mixed municipal solid waste be successfully utilized for effective composting of selectively collected biowaste?

Although the requirements for overall recycling rates can only be met when organic recycling is not overlooked, information is scarce regarding adaption to biowaste composting of existing mechanical–biological treatment (MBT) plants originally designed for stabilization of organic municipal solid waste (OFMSW). Thus, this study aimed to assess the suitability of the operational conditions in the biological part of a full-scale MBT plant now used for stabilization of OFMSW (working line: closed-module–covered-pile–open-pile) with a view to producing compost from biowaste. Temperatures above 75 °C were maintained in the closed module and reached again in the covered pile, indicating that intensive organic-matter mineralization occurred in both stages. In the covered pile, the temperature sharply decreased, indicating depletion of easily biodegradable organic matter. An aerobic 4-day respiration test (AT4) value below 10 mg O2/g dry matter, the cut-off for assessing compost stability, was obtained after 8 weeks. However, a high content of humic substances (HS), reflecting compost maturity, was obtained only after 120 days. The increase in HS content proceeded in two phases. In the first phase (45–84 day), the rate constant and the rate of HS formation were lower than in the second phase (84–120 day) (0.072 vs. 0.087 day−1, 1.97 vs. 3.06 mg C/(g organic matter·d)). All the above-mentioned indicators and the nutrient content (N, P, K, Mg, Ca) in the compost indicates that the biological stage of an MBT plant can successfully treat biowaste. This is in accordance with a circular economy and will contribute to increasing recycling rates.

A comparative techno-economic assessment of fast pyrolysis, hydrothermal liquefaction, and intermediate pyrolysis of municipal solid waste for liquid transportation fuels production

The conversion of municipal solid waste (MSW) to transportation fuels can be an attractive route to reduce greenhouse gas emissions from the transportation and municipal sectors. Thermochemical conversion routes like hydrothermal liquefaction (HTL), fast pyrolysis (FP), and intermediate pyrolysis (IP) have been shown to be adept at converting organic dominant MSW into bio-crude or bio-oil. However, to produce compatible transportation grade fuels, it is necessary to upgrade the intermediate product (bio-crude or bio-oil) from all the processes, the extent of which differs depending on the process. Moreover, depending on the conversion technique, the production configuration can be either centralized or decentralized. In a centralized system, feed is transported to a facility to produce the intermediate and upgrade it (on-site upgrading), while in a decentralized system, the intermediate is produced elsewhere and transported to an upgrading facility (off-site upgrading).. Four scenarios were developed and modeled to compare the cost of production of gasoline, diesel and jet fuel from bio-crudes produced from HTL, FP, and IP.. The scenarios are: 1) a centralized HTL plant (C-HTL); 2000 dry t per day; on-site upgrading, 2) a centralized FP plant (C-FP); 2000 dry t per day; on-site upgrading, 3) a decentralized FP plant (D-FP); 50 dry t per day; off-site upgrading, and 4) a decentralized IP plant; 12 dry t per day; off-site upgrading.. Jet fuel was the primary fuel for comparison and the production costs were calculated to be $ 0.72, $ 0.85, $ 1.04, and $ 0.81 per liter for the C-HTL, the C-FP, the D-FP, and the D-IP plants, respectively. Secondary products (gasoline and diesel) can be produced alongside in cost ranges of $ 0.97 - $ 1.40 per liter and $ 1.02 - $ 1.47 per liter, respectively. The information conveyed in this study helps to identify the potential of thermochemical conversion processes to produce transportation fuels at competitive prices. The critical barriers to adopt such large-scale production processes and the opportunities of small-scale decentralized production are also mentioned. The outcomes of this study can be used to direct research and investment to address the major roadblocks that are slowing the extensive development of these technologies.

Quality and Fertility Assessments of Municipal Solid Waste Compost Produced from Cleaner Development Mechanism Compost Projects: A Case Study from Uganda

Despite the fact that compost projects under the Cleaner Development Mechanism (CDM) have been implemented in Sub-Saharan Africa in recent years, there is a paucity of information on the quality of compost produced from the compost plants. This study fills this gap by evaluating the properties of MSWC produced from 12 CDM plants in Uganda based on quality and fertilizing indices. pH, Pb N, K, P, Mn, Cd, Ca, Mg, Cu, Fe, Cr, Zn, OC, and CN levels differed significantly between locations. MSWC’s Fertility Indices (FI) ranged from 1.9 to 2.9, with Mbarara having the highest (2.9) and Soroti having the lowest (1.9). Fort Portal, Mbarara, Kasese, and Masindi have Clean Indices (CI) ranging from 3.8 to 4.9. According to the results of the fertility and Clean Indices analysis, all MSW composts generated at CDM facilities have low fertilizing capacity and poor quality and are classified as Class RU-1, which does not meet international and national compost criteria. As a result, these composts cannot be utilized as fertilizers and can only be used as soil conditioners under certain conditions. Windrow composting has been proven to be a viable method for lowering huge amounts of organic municipal solid waste in urban areas, and it can be scaled up to other parts of the world according to this study. Authorities must, however, engage urban citizens in waste separation at the source and MSWC enrichment with organic sources. This will aid in improving its quality and fertilizing capacity, as well as in ensuring that the MSWC produced is uniform and suited for use in agriculture and the market.

Impact of temperature, inoculum flow pattern, inoculum type, and their ratio on dry anaerobic digestion for biogas production

This study is aimed to apply dry anaerobic digestion (DAD) for methane (CH4) enriched biogas production from unsorted organic municipal solid waste (MSW). Cumulative biogas production was monitored for 35 days of operation in batch digesters at fixed feedstock to inoculum (F/I) ratio 2. Anaerobic sludge (AS) and cow manure (CM) were used as inoculum in single and mixed modes. Several process parameters such as inoculum flow pattern (single layer, multilayer, and spiral), digestion temperature (25 to 40 °C), inoculation modes (single and mixed mode), and inoculation proportion (AS:CM = 1:1, 1:2, 1:3, and 2:1) were investigated to determine the optimum DAD conditions to maximize the CH4 laden biogas yield. The study of inoculum flow pattern showed that digester with multilayer inoculum configuration generated the maximum 555 mL cumulative biogas with the production rate of 195 mL/day (at 25 °C). Biogas production rate and cumulative biogas production were found to increase with a rise in temperature and the maximum values of 380 mL/day and 1515 mL respectively were observed at 37 °C. The mixed mode of inoculation containing AS and CM augmented the biogas yield at previously optimized conditions. Final results showed that digester with multilayer inoculum flow pattern at 37 °C produced 1850 mL cumulative biogas with 1256.58 mL CH4/kg volatile solid (VS) when the mixed inoculum was used at the AS:CM—1:2 ratio. Biogas production with this significant amount of CH4 justifies the use of the DAD process for energy (biogas) generation from widely available biomass feedstock (MSW), offering various advantages to the environment.

Stabilization of organic municipal solid waste by composting

The article examines the process of vermicomposting of municipal organic waste. To determine the optimal composition of bio humus, various options and proportions of mixing organic waste with soil are considered. In the course of the study, three different variations of organic waste were developed, mixed with manure: 1 — soil, paper, vegetables, fruits, wood waste, cow manure (1:0.5:1); 2 — soil, vegetables and fruits, wood waste (1:1); 3 — soil, cow manure (1:1). The results of the experiment showed that all substrates have high germination of tomato seeds. However, a mixture of soil, paper, vegetables, fruits, wood waste, cow manure increases the yield of tomatoes by 11 % compared to other experimental substrates. Vermicomposting E. was performed using E. fetida worms. This kind of worms is characterized by high yield. For vermic content, the moisture content must be at the level of 60 %. Bacteria also play an important role in vermicompost. With air humidity below 40 %, their activity decreases and stops at temperatures below 10 %. In this experiment, solid organic waste processing technology reduces the shortage of cheap organic fertilizers in the market and offers new opportunities for profit for small enterprises. The results obtained can be used for processing organic waste of the city on an industrial scale and applied as fertilizer in agriculture.

A selection bias approach in the circular economy context: The case of organic municipal solid waste in Italy

Organic waste is often indicative of the amount of food waste, and it primarily reflects the consumption habits of households. As underlined by the applicable principles of the Circular Economy (CE), prevention is always the first choice when dealing with waste but evaluating the prevention framework without considering the application of waste separation policies appears to be a complex task. Considering Italian municipal waste management, the implementation of separation policies has been delayed in several provinces. It is difficult to assess the effectiveness of prevention policies established by international and national authorities in this context. The lack of organic waste separation is registered as a missing value in datasets: such instances are often non-random. The research objective of this work is to assess whether economic activity affects organic waste generation and, once the selection bias has been investigated, try to assess the overall implications. Initial findings corroborate the Environmental Kuznets Curve Hypothesis under biased and unbiased estimations. The tipping point is relatively lower when the inverse Mills Ratio is considered, which is positive. Hence, an increase of the expected economic activity requirement could result in a cost that municipalities incur when delaying the enforcement of separation policies. The missing information undermines the potential feedback from practitioners and other stakeholders capable of steering expectations: the unobserved flows have to reach a certain level before being collected.

Valorization of Hazardous Organic Solid Wastes towards Fuels and Chemicals via Fast (Catalytic) Pyrolysis

The management of municipal and industrial organic solid wastes has become one of the most critical environmental problems in modern societies. Nowadays, commonly used management techniques are incineration, composting, and landfilling, with the former one being the most common for hazardous organic wastes. An alternative eco-friendly method that offers a sustainable and economically viable solution for hazardous wastes management is fast pyrolysis, being one of the most important thermochemical processes in the petrochemical and biomass valorization industry. The objective of this work was to study the application of fast pyrolysis for the valorization of three types of wastes, i.e., petroleum-based sludges and sediments, residual paints left on used/scrap metal packaging, and creosote-treated wood waste, towards high-added-value fuels, chemicals, and (bio)char. Fast pyrolysis experiments were performed on a lab-scale fixed-bed reactor for the determination of product yields, i.e., pyrolysis (bio)oil, gases, and solids (char). In addition, the composition of (bio)oil was also determined by Py/GC-MS tests. The thermal pyrolysis oil from the petroleum sludge was only 15.8 wt.% due to the remarkably high content of ash (74 wt.%) of this type of waste, in contrast to the treated wood and the residual paints (also containing 30 wt.% inorganics), which provided 46.9 wt.% and 35 wt.% pyrolysis oil, respectively. The gaseous products ranged from ~7.9 wt.% (sludge) to 14.7 (wood) and 19.2 wt.% (paints), while the respective solids (ash, char, reaction coke) values were 75.1, 35, and 36.9 wt.%. The thermal (non-catalytic) pyrolysis of residual paint contained relatively high concentrations of short acrylic aliphatic ester (i.e., n-butyl methacrylate), being valuable monomers in the polymer industry. The use of an acidic zeolitic catalyst (ZSM-5) for the in situ upgrading of the pyrolysis vapors induced changes on the product yields (decreased oil due to cracking reactions and increased gases and char/coke), but mostly on the pyrolysis oil composition. The main effect of the ZSM-5 zeolite catalyst was that, for all three organic wastes, the catalytic pyrolysis oils were enriched in the value-added mono-aromatics (BTX), especially in the case of the treated wood waste and residual paints. The non-condensable gases were mostly consisting of CO, CO2, and different amounts of C1–C4 hydrocarbons, depending on initial feed and use or not of the catalyst that increased the production of ethylene and propylene.