Sustainable Valorization of Animal Manure and Recycled Polyester: Co-pyrolysis Synergy

Toxicity assessment of animal manure composts containing environmental microplastics by using earthworms Eisenia andrei

Nowadays, animal manure composting constitutes a sustainable alternative for farmers to enhance the level of nutrients within soils and achieve a good productivity. However, pollutants may be present in manures. This study focuses on the detection of environmental microplastics (EMPs) into composts, as well as on the assessment of their potential toxicity on the earthworm Eisenia andrei. To these aims, animals were exposed to two types of compost, namely bovine (cow) and ovine (sheep) manure, besides to their mixture, for 7 and 14 days. The presence and characterization of EMPs was evaluated in all the tested composts, as well as in tissues of the exposed earthworms. The impact of the tested composts was assessed by a multi-biomarker approach including cytotoxic (lysosomal membrane stability, LMS), genotoxic (micronuclei frequency, MNi), biochemical (activity of catalase, CAT, and glutathione-S-transferase, GST; content of malondialdehyde, MDA), and neurotoxic (activity of acetylcholinesterase, AChE) responses in earthworms. Results indicated the presence of high levels of EMPs in all the tested composts, especially in the sheep manure (2273.14 ± 200.89 items/kg) in comparison to the cow manure (1628.82 ± 175.23 items/kg), with the size <1.22 μm as the most abundant EMPs. A time-dependent decrease in LMS and AChE was noted in exposed earthworms, as well as a concomitant increase in DNA damages (MNi) after 7 and 14 days of exposure. Also, a severe oxidative stress was recorded in animals treated with the different types of compost through an increase in CAT and GST activities, and LPO levels, especially after 14 days of exposure. Therefore, it is necessary to carefully consider these findings for agricultural good practices in terms of plastic mitigation in compost usage, in order to prevent any risk for environment health.

Thermo-kinetic behaviour of green synthesized nanomaterial enhanced organic phase change material: Model fitting approach

Metal, carbon and conducting polymer nanoparticles are blended with organic phase change materials (PCMs) to enhance the thermal conductivity, heat storage ability, thermal stability and optical property. However, the existing nanoparticle are expensive and need to be handle with high caution during operation as well during disposal owing to its toxicity. Subsequently handling of solid waste and the disposal of organic PCM after longevity usage are of utmost concern and are less exposed. Henceforth, the current research presents a new dimension of exploration by green synthesized nanoparticles from a thorny shrub of an invasive weed named Prosopis Juliflora (PJ) which is a agro based solid waste. Subsequently, the research is indented to decide the concentration of green synthesized nanoparticle for effective heat transfer rate of organic PCM (Tm = 35-40 °C & Hm = 145 J/g). Furthermore, an in-depth understanding on the kinetic and thermodynamic profile of degradation mechanism involved in disposal of PCM after usage via Coats and Redfern technique is exhibited. Engaging a two-step method, we fuse the green synthesized nanomaterial with PCM to obtain nanocomposite PCM. On experimental evaluation, thermal conductivity of the developed nanocomposite (PCM + PJ) increases by 63.8% (0.282 W/m⋅K to 0.462 W/m⋅K) with 0.8 wt% green synthesized nanomaterial owing to the uniform distribution of nanoparticle within PCM matrix thereby contributing to bridging thermal networks. Subsequently, PCM and PCM + PJ nanocomposites are tested using thermogravimetric analyzer at different heating rates (05 °C/min; 10 °C/min; 15 °C/min & 20 °C/min) to analyze the decomposition kinetic reaction. The kinetic and thermodynamic profile of degradation mechanism involved in disposal of PCM and its nanocomposite of PCM + PJ provides insight on thermal parameters to be considered on large scale operation and to understand the complex nature of the chemical reactions. Adopting thirteen different chemical mechanism model under Coats and Redfern method we determine the reaction mechanism; kinetic parameter like activation energy (Ea) & pre-exponential factor (A) and thermodynamic parameter like change in enthalpy (ΔH), change in Gibbs free energy (ΔG) and change in entropy (ΔS). Dispersion of PJ nanomaterial with PCM reduces Ea from 370.82 kJ/mol-1 to 342.54 kJ/mol-1 (7.7% reduction), as the developed nanomaterial is enriched in carbon element and exhibits a catalytic effect for breakdown reaction. Corresponding, value of ΔG for PCM and PCM + PJ sample within heating rates of 05-20 °C/min varies between 168.95 and 41.611 kJ/mol-1. The current research will unbolt new works with focus on exploring the pyrolysis behaviour of phase change materials and its nanocomposite used for energy storage applications. This work also provides insights on the disposal of PCM which is an organic solid waste. The thermo-kinetic profile will help to investigate and predict the optimum heating rate and temperature range for conversion of micro-scale pyrolysis to commercial scale process.

Upcycling textile waste using pyrolysis process

Rapidly changing fashion trends have generated tremendous amounts of textile waste globally. Textile waste is composed of a variety of substances (natural, synthetic, organic, and inorganic fibers). The inhomogeneity and complex nature of textile waste makes recycling economically challenging. Pyrolysis is a thermochemical process that transforms waste feedstocks of an inhomogeneous and complex nature into value added products (i.e., waste upcycling). This article provides a systematic review of the currently available and investigated pyrolysis processes to upcycle textile waste (e.g., material and energy recovery). The challenges in the pyrolysis process of textile waste are discussed, and relevant future research needs are recommended. Despite these challenges, pyrolysis will be an effective end-of-life option for textile waste if continuous research and development activities are conducted.

Decarbonizing Vehicle Transportation with Hydrogen from Biomass Gasification: An Assessment in the Nigerian Urban Environment

Tailpipe emissions from vehicles consist of CO2 and other greenhouse gases, which contribute immensely to the rise in global temperatures. Green hydrogen produced from the gasification of biomass can reduce the amount of CO2 emissions to zero. This study aims to provide a modelling framework to optimize the production of hydrogen from biomass waste obtained from different cities, for use in the road transport sector in Nigeria. A gasification model with post-treatment shift conversion and CO2 removal by adsorption is proposed. In this study, six cities are simulated based on technical and environmental considerations, using the Aspen Plus software package. The results revealed that Kaduna has the highest hydrogen generation potential of 0.148 million metric tons per year, which could reduce CO2 emissions to 1.60 and 1.524 million metric tons by the displacement of an equivalent volume of gasoline and diesel. This amounts to cost savings of NGN 116 and 161.8 billion for gasoline and diesel, respectively. In addition, the results of the sensitivity analysis revealed that the steam-to-biomass ratio and the temperature of gasification are positively correlated with the amount of avoided CO2 emissions, while the equivalence ratio shows a negative correlation.

Synergetic Effects during Co-Pyrolysis of Sheep Manure and Recycled Polyethylene Terephthalate

Continuous growth in energy demand and plastic waste production are two global emerging issues that require development of clean technologies for energy recovery and solid waste disposal. Co-pyrolysis is an effective thermochemical route for upgrading waste materials to produce energy and value added products. In this study, co-pyrolysis of sheep manure (SM) and recycled polyethylene terephthalate (PET) was studied for the first time in a thermogravimetric analyzer (TGA) in the temperature range of 25-1000 °C with heating rates of 10-30-50 °C min^-1 under a nitrogen atmosphere. The synergetic effects of co-pyrolysis of two different waste feedstock were investigated. The kinetic parameters are determined using the Flynn-Wall-Ozawa (FWO) model. The results revealed that the mean values of apparent activation energy for the decomposition of sheep manure into a recycled polyethylene terephthalate blend are determined to be 86.27, 241.53, and 234.51 kJ/mol, respectively. The results of the kinetic study on co-pyrolysis of sheep manure with plastics suggested that co-pyrolysis is a viable technique to produce green energy.

Recent Progress in Low-Cost Catalysts for Pyrolysis of Plastic Waste to Fuels

The catalytic and thermal decomposition of plastic waste to fuels over low-cost catalysts like zeolite, clay, and bimetallic material is highlighted. In this paper, several relevant studies are examined, specifically the effects of each type of catalyst used on the characteristics and product distribution of the produced products. The type of catalyst plays an important role in the decomposition of plastic waste and the characteristics of the oil yields and quality. In addition, the quality and yield of the oil products depend on several factors such as (i) the operating temperature, (ii) the ratio of plastic waste and catalyst, and (iii) the type of reactor. The development of low-cost catalysts is revisited for designing better and effective materials for plastic solid waste (PSW) conversion to oil/bio-oil products.

Thermal degradation characteristics and gasification kinetics of camel manure using thermogravimetric analysis

In this work, the sustainable valorisation of camel manure has been studied using thermogravimetric analysis. The gasification tests were performed from ambient conditions to 950 °C at 10, 20, and 50 °C/min under an O₂ environment. The TGA data were applied to determine the kinetics of the O₂ gasification. Single-heating rate models (Arrhenius and Coats-Redfern) and multi-heating rate models (Distributed activation energy, Friedman, Flynn-Wall-Ozawa, Starink, and Kissinger-Akahira-Sunose) were applied to estimate the kinetics of the process. Between the two single-heating rate models, the Coats-Redfern method fitted best with the experimental data. Among the multi-heating rate models, the Flynn-Wall-Ozawa model fitted best with the experimental results. The kinetic parameters-frequency factor, activation energy, and order of reaction were estimated using the Flynn-Wall-Ozawa model (the best-fitting model) and the estimated kinetic parameters were used to calculate the thermodynamic properties-Gibbs free energy, enthalpy, and entropy. The information on these kinetic and thermodynamic properties can be useful for the design of gasifiers and for optimising the O₂ gasification operating conditions.

Thermal degradation characteristics and gasification kinetics of camel manure using thermogravimetric analysis

In this work, the sustainable valorisation of camel manure has been studied using thermogravimetric analysis. The gasification tests were performed from ambient conditions to 950 °C at 10, 20, and 50 °C/min under an O₂ environment. The TGA data were applied to determine the kinetics of the O₂ gasification. Single-heating rate models (Arrhenius and Coats-Redfern) and multi-heating rate models (Distributed activation energy, Friedman, Flynn-Wall-Ozawa, Starink, and Kissinger-Akahira-Sunose) were applied to estimate the kinetics of the process. Between the two single-heating rate models, the Coats-Redfern method fitted best with the experimental data. Among the multi-heating rate models, the Flynn-Wall-Ozawa model fitted best with the experimental results. The kinetic parameters-frequency factor, activation energy, and order of reaction were estimated using the Flynn-Wall-Ozawa model (the best-fitting model) and the estimated kinetic parameters were used to calculate the thermodynamic properties-Gibbs free energy, enthalpy, and entropy. The information on these kinetic and thermodynamic properties can be useful for the design of gasifiers and for optimising the O₂ gasification operating conditions.

Slow pyrolysis of municipal solid waste (MSW): A review

In recent years, extensive studies have been carried out to improve our knowledge of the reactor operations and system performance in thermal pyrolysis of municipal solid wastes (MSW). However, the fundamentals of MSW pyrolysis and their engineering applications remain unsatisfactorily explored. This paper is a review of the pyrolysis of MSW and synergistic co-pyrolysis of the constituents of MSW with reference to pyrolytic performance, the distribution and energy content of the end products, and the mechanisms of the synergistic effects. The prospects for, and challenges of, the MSW pyrolysis process are provided. A MSW pyrolytic process with maximal energy recovery and minimal carbon footprint is proposed.

Continuous Pyrolysis Technology for Oily Sludge Treatment in the Chain-Slap Conveyors

In the process of petroleum exploitation, the annual production of oily sludge in China’s petroleum exploitation industry alone has exceeded one million tons, which causes great harm to the environment. In order to face this problem, a variety of treatment methods have been sprung out, but the most of them are polluting the local soil and groundwater eco-environment. Pyrolysis technology for sludge treatment has several advantages, which have already made it a mainstream approach attracting worldwide attention. In this work, oily sludge from Yanshan Petrochemical Company was processed at the newly developed industrial-scale reactor. The sludge transportation in the whole system was achieved by the use of chain plate conveying, which has the advantages of preventing coking, effective sealing of sludge inlet and outlet, etc. First, lab-scale experiments were carried out at temperatures between 450 °C and 600 °C to obtain the best reaction conditions in the industrial-scale equipment. It was found that the maximum pyrolysis oil yield of 17.1 wt.% was obtained at 500 °C. The properties of oily sludge and related compositional characterization of the products (permanent gas, pyrolysis oil, and pyrolysis char) after the treatment were comprehensively analyzed. The study showed that the oily sludge in the reactor was completely converted, and resource utilization of the feedstock could be realized.