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Environmental issues, legal requirements, and economic benefits of recycling activities lead to the development of reverse logistics operations and waste management. The current research considers a closed-loop supply chain for a cardboard recycling network including multiple suppliers and production stages. A mixed integer linear programming model is proposed to optimize the paper and cardboard recycling network, and a robust optimization approach is utilized to deal with demand uncertainty in this network. The model maximizes the total profit. It considers the operation, transportation, purchasing and holding inventory costs as well. Moreover, to illustrate the application of the proposed model, a real-world cardboard closed-loop supply chain design is investigated. The proposed model considers the option to open a new recycling center in the current network. The proposed model determines the optimal quantities of the waste paper, paper, sheet and cardboard that flow in this network. Finally, the computational analysis indicated that the proposed model provides efficient solutions for the studied cardboard closed-loop network.

This study presents a novel decentralized sanitary separation system as a zero-discharge solution for blackwater (BW) (faeces, urine and toilet paper) treatment for remote tourist facilities located in sensitive areas. The system operates with low water and energy consumption, enables safe operation and requires low maintenance. The BW was collected from two vacuum toilets (VTs) (0.8 L flush water) and separated in peat filters (PFs) to obtain a liquid fraction (LF) and a solid fraction (SF) of the BW. The LF from the PFs was thereafter treated in a biofilter (BF) and finally evaporated in the evaporation module (EM) powered by solar vacuum collectors (SVC). In the PFs, particles larger than 1 mm were reduced from the BW by 96.5%. Furthermore, the total suspended solids (TSS) mass removal efficiency of the PFs averaged 51.5%. Reduction of ammonia through nitrification was noticeably enhanced after 100 days of the system operation (max. 55.8%). 21.2% or 0.54 kg of total phosphorus (TP) was retained in the PFs, to be further composted and reused for agricultural purposes. An additional 5% or 0.10 kg of TP was retained in the BF. The final step of the LF treatment was in the EM at a sanitizing temperature of >60 °C to prevent the release of human pathogens into environment. With a total electricity consumption of 9.1 kWh/day and a heat consumption of approximately 5.1 kWh/day gained by the SVC, the system successfully integrated different approaches to treating the BW, recycling nutrients, and removing pathogens.

This article is a reply to “Comment on the paper: Ben Ali S, Jaouali I, Souissi-Najar S, Ouederni A, Characterization and adsorption capacity of raw pomegranate peel biosorbent for copper removal, Journal of Cleaner Production (2016)”. Our paper does not contain scientific errors, interpretations, calculations or conclusions in different study parts (Characterization, adsorption, optimization, kinetic, isotherm and thermodynamic study) as Tran Nguyen Hai claimed. We take advantage of this opportunity to correct if there are any typing errors and to improve the FTIR wave number table. That, many objections raised by Tran Nguyen Hai come from (1) comparison of figures with different x-axis scale; (2) calculation and verification based on inappropriate units; (3) comparing to self nonexistent results in cited paper; (4) comparing and evaluating our results dealing with pomegranate peel to orange peel substrate; (5) proposing basic analytical analysis whereas more sophisticated analysis were used; (6) basing on the uncorrected proof version of our paper. Thereafter a reply to any objection raised by Tran Nguyen Hai in Tran, (2017) .

To meet the demand of pulp and paper as well as the environmental legislation the pulp production with eco-friendly approach is desired. This paper presented the state of affairs of Indian and world pulp and paper industry. It also reviewed the discharge of toxic substances from pulp bleaching process and the alternatives for reduction of these toxic substances from pulp bleaching process. The pulp and paper industry is continually changing the bleaching process to minimize the use of chlorine and chlorine based compounds in order to satisfy regulatory and market demands. Imminent to have the minimum impact on environment from bleach plant peracetic acid is the prospective candidate. Use of peracetic acid is a promising technology as it has the capability to reduce/replace chlorine based compounds from pulp bleaching process. This paper reviewed the peracetic acid pulp bleaching and its impact on pulp properties and presented the eco-friendly bleaching process for mixed hardwood.

In the current paper, a suggested process of coupled ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO) to produce isotonic solution (IS) and drinking water from coastal well water was investigated. Due to its high fouling potential, the feed water was pretreated using UF. Results showed that UF eliminates almost the totality of natural organic matter (NOM), and a relatively high portion of calcium (calcium rejection ∼75%) due to the complex Ca-NOM formed. To understand the fouling mechanism, previously developed mathematical models and equations were adopted. It was shown that the fouling mechanism for UF fits the blocking pores model. For NF, the extended model using cross-flow mode showed a slight difference compared to UF (No compression cake phase). It was concluded that, with some experimental precautions, fouling mechanism of the NF membrane used is internal pore blocking mechanism. Due to its attractive quality, the brine of NF was used to produce drinking water by RO treatment. The energy consumption of the UF-NF-RO system was investigated for different operating conditions. Finally, the permeate of the UF-NF process was compared to a commercialized IS. It was found that the two solutions revealed a remarkable similarity. However, a specific post-treatment should be added to the process to accomplish the pharmaceutical exigencies of IS.

Many food manufacturers in the U.S. are attempting to reduce the environmental footprint of their high biological oxygen demand (BOD) effluents due to increased risk of financial surcharges from publically owned treatment works, water scarcity issues and changes in societal opinions about large scale biodegradable waste releases. Managers at these firms are often reluctant to consider on-site processing due to their fear of committing to unfamiliar and complex wastewater treatment processes with excessive capital expenditures. While an abundance of research has been performed on the use of biochar (i.e. charcoal intended to be used for agricultural purposes produced from organic waste feedstocks via pyrolysis) to mitigate the problem of heavy metal ions from traditional manufacturing effluents by filtration, little is known on biochar's potential to treat high BOD industrial aqueous food wastes. This paper attempts to fill this gap by gauging the environmental and financial sustainability of a vertically integrated biochar filtration system, wherein maple wood biochar is used to treat high BOD tofu whey effluent and subsequently re-utilize that material as an enriched value-added soil amendment to improve crop quality and yields in basil and lettuce. Results show whey filtered biochar significantly increased fresh weight in basil and lettuce above the no biochar and unfiltered biochar controls. This novel approach could potentially help food and beverage manufacturers sustainably reduce their carbon and water footprints by harvesting and monetizing the nutrients found in their wastewaters, while allowing farmers to close regional nutrient cycles by returning nutrient rich carbon to the soil and reduce the use of synthetic fertilizers or costly peat moss or perlite soil amendments in greenhouses.

The Eastman process discharges a wastewater stream with high organic contents. Its chemical oxygen demand (COD) and flowrate are up to 60,000 mg/L and 1011 kg/h, respectively. The ecological environment will be polluted severely in case of an inappropriate disposal of this wastewater. This paper proposes a novel “waste control by waste” strategy to dispose of such a wastewater with a combination of modeling and experiment methods. First, several possible schemes are simulated and evaluated with Aspen Plus software. One scheme that employs internally synthesized 2,2,4-trimethyl-1,3-pentanediol di-isobutyrate (TXIB) to extract organics is chosen because it can alleviate the recovery problems of solvent. The simulation of this scheme shows a mass fraction increase of water in disposed wastewater from 96.941% to 98.572%. Second, experiments concerning extraction and reaction are performed to obtain the requisite parameters for simulation. The optimum operating conditions for extraction column are obtained: room temperature and pressure, the number of trays is 8, the flowrate of extractant is 350 kg/h. The optimum operating conditions for esterification reaction are obtained: reaction time is 3.5 h, catalyst concentration is 8% and reaction temperature is 130 °C. Finally, the importance of each variable in the wastewater treatment process is evaluated based on complex network theory, and two variables comprised of recycle extractant flow and reactor temperature are selected accordingly. One control scheme is proposed based on selected key variables after its anti-disturbance ability is verified with Aspen Dynamics software.

Aerobic Granulation Technology for treatment of wastewater is developed in last two decades. Aerobic Granules are special type of self-immobilization of microorganisms, without any surface medium for growth of microbial film. They have compact cores and have high diffusional confrontations to external particles and, hence have high acceptance of the toxic compounds to their integral cells. Most aerobic granules are large and have a compact core, and so are recommended for use in the biological treatment of high-strength industrial wastewaters. This technology requires small foot print, 25% of the area of conventional activated sludge setup and this process can reduce up to 50% on energy-costs. This paper reviews on start-ups, advances in aerobic granulation technology from laboratory studies to pilot scale and to its full-scale application for treatment of different types of domestic and industrial wastewater. Gaps in knowledge and new ideas for future work of aerobic granulation technology are also being discussed.

The clarification of tailings slurry using polymer flocculants has been widely used in the mining industry to promote the cleaner production of mineral resources. In this paper, a data-driven prediction model was proposed using gradient boosting machine (GBM) for the non-linear relationship modelling and firefly algorithm (FA) for GBM hyper-parameters tuning. Two studies were performed, among which the main study omitted the influence of chemical characteristics of mineral processing tailings (MPT) while the supplementary study considered. For the main study, 27 types of MPT and 4 types of anionic flocculants were used to prepare the dataset. The flocculation performance was represented by the initial settling rate (ISR) and its influencing variables were selected to be the particle size distribution (PSD) of MPT, the solids content of tailings slurry, the flocculants type, and the flocculants dosage. For the supplementary study, the chemical characteristics of 7 types of MPT were also considered as influencing variables and its influence on the predictive performance of GBM was investigated. The main study shows that the optimum GBM model achieved a correlation coefficient of 0.841 between the predicted and experimental ISR values on the testing set, denoting it was robust in predicting the ISR of the flocculation. Compared with the solids content, the flocculants dosage and the flocculants type, the PSD of MPT was found to be the most significant influencing variable for the flocculation with an importance score of 0.420 out of 1. The supplementary study shows that the predictive performance of GBM could be improved considering chemical compositions of MPT, which were also important influencing variables for the flocculation process.

The use of biomass for energy production is one way to ensure energy security and address the environmental issues related to the use of fossil fuels in developing countries. Small and medium-sized enterprises (SMEs) need electric power and thermal energy for their activities. In Burkina Faso, this type of thermal energy is generally produced by SMEs from firewood. However, cashew companies produce a large amount of waste (shell, press cake, nut shell liquid) which can be converted into fuel. Separating the cashew nut from the shell requires two energy-intensive steps: roasting and drying. The energy is provided by cashew shells which are usually burned in boilers, but this method results in the production of anacardic acid and smoke both of which are irritating and which may be carcinogenic due to the presence of cashew nuts shell liquid (CNSL). This paper describes the production of energy from cashew waste by making briquettes out of the press cake, which is left over after the removal of CNSL from the nut shell. The process consists in carbonizing the press cake at a temperature of 350 °C and grinding to a grain size of 0.5 mm. The resulting charcoal powder is then mixed with water and a binding agent (cassava starch), in this case cassava starch selected for its physical-chemical properties, availability in the local market, and its low price. The resulting mixture is then densified in a screw press to obtain briquettes 5.5 cm in diameter and 10 cm in length. Several proportions of water and cassava starch were tested and the best briquettes were obtained with a mixture of 35% of water, 10% of cassava starch and 55% of press cake charcoal. The mechanical and physicochemical analysis of briquettes gave a net calorific value of 25.7 MJ/kg, a density of 0.91, a compressive strength index of 382.89 kPa and an impact resistance index of 61.10. A water boiling test performed afterwards showed that the combustion performance of the briquettes was the same as that of wood charcoal.

Straw pulping plays a vital role in virgin pulp supply and regional agricultural residue utilization. However, a significant decrease in its production has been observed. From an environmental perspective, why has there been a sharp decrease in straw pulping? Are there any innovations in straw pulp production that alleviate the heavy environmental burdens of straw pulping? In this study, factors contributing to the decrease in straw pulp are examined. An innovative technique to produce straw pulp is introduced and its environmental performance is analyzed and compared with conventional pulping. The results show that the main reasons contributing to the environmental burdens of straw pulping lie in the difficulties in black liquor extraction and alkaline recovery for the black liquor. Technical processes are changed in the innovative technique of straw pulping through using a rapid displacement cooking process, converting black liquor into fertilizers, utilizing total chlorine-free bleaching, etc. The new technique (Case B) achieves superior environmental performance than that of the conventional technique (Case A) from a carbon metabolism perspective. Specifically, 1022.90 kg and 857.80 kg of biogenic-carbon (bio-carbon), and 594.32 kg and 628.13 kg of fossil-carbon are needed to make 1 ton of bleached straw pulp for Case A and Case B, respectively. The carbon efficiencies for Case A, Case B (when pulp is the only desired product) and Case B (when including other products) are 39.10%, 46.63% and 92.21%, respectively. The carbon factors for Case A, Case B (when pulp is the only desired product) and Case B (when including other products) are 3.66, 3.60 and 1.86 kg CO2-eq, respectively. In addition, the corresponding E factors, which reflect the waste generation level, are 3.20, 2.69, and 1.39 kg, respectively. The new technique for straw pulping, which follows the principle of a circular economy by fully utilizing resources and reducing the generation of waste, achieves both economic and environmental benefits. It is a promising technique for straw pulping.

This paper reports pollutant removal performances from mixed industrial wastewater employing subsurface flow constructed wetland systems in Bangladesh. Two parallel hybrid wetland trains were established; each train included a vertical flow (VF) followed by a horizontal flow (HF) wetland. One hybrid system was packed with construction materials (i.e. recycled bricks), whereas the other system included agricultural by-products (i.e. sugarcane bagasse). All wetland units were planted with Canna indica. The hybrid trains were operated under non recirculation and recirculation phases; input hydraulic loading across each VF system ranged between 219.3 and 438.0 mm/d. Mean nitrogen, organics, solids, phosphorus and color removals across the hybrid systems were 67.5–80.0, 74.0–85.0, 55.0–95.0, 64.0–89.0 and 46.0–83.0% respectively. Lower input biodegradation ratio influenced organics removal routes in wetland systems that employed recycled bricks. In contrast, organic contents of sugarcane bagasse material supported microbial routes in the other system. VF wetland with organic media achieved higher TN removal rates (1.82 g/m2 d), due to internal carbon (C) generation. Higher phosphorus removals (89.0%) were observed in hybrid system packed with recycled brick media, due to adsorption process. HF wetland packed with recycled brick was efficient in removing color compounds, whereas the other HF system (with organic media) showed high sulfate removals. Nitrogen and BOD removal improvement was observed in VF wetland (packed with recycled brick media) during recirculation period; in contrast, effluent recirculation reduced removal rates of such pollutants in VF system that employed organic media. In general, this study shows potential application of particular materials as the main media of wetland systems, to achieve pollutant removals from industrial wastewaters in Bangladesh.

In this paper, the enrichment of methane by membrane technology was studied by employing (i) a model as well as (ii) a real biogas mixture produced on a laboratory-scale. Thereafter, the endurance of the process was tested at an existing biogas plant. The commercial gas separation module under investigation contained hollow fiber membranes with a polyimide selective layer. During the measurements, the effect of critical factors (including the permeate-to-feed pressure ratio and the splitting factor) was sought in terms of the (i) CH4 content on the retentate-side and (ii) CH4 recovery, which are important measures of biogas upgrading efficiency. The results indicated that a retentate with 93.8 vol% of CH4 – almost biomethane (>95 vol% of CH4) quality – could be obtained using the model gas (consisting of 80 vol% of CH4 and 20 vol% of CO2) along with 77.4% CH4 recovery in the single-stage permeation system. However, in the case of the real biogas mixture, ascribed primarily to inappropriate N2/CH4 separation, the peak methane concentration noted was only 80.7 vol% with a corresponding 76% CH4 recovery. Besides, longer-term experiments revealed the adequate time-stability of membrane purification, suggesting such a process is feasible under industrial conditions for the improvement of biogas quality.

Sludge microbial fuel cell (SMFC) is capable of extracting biomass energy directly from the sludge while generating electricity. However, most of organic matters in the excess sludge are the cell substances that are difficult to be used by microorganism directly. In this paper, adding graphene oxide (GO) and reduced graphene oxide (rGO) in SMFC was proposed and their advantages were reflected by no requiring external energy, in-situ promoting the electricity production and reducing sludge effectively. The results showed that the contents of lactate dehydrogenase (LDH) for adding 0.4 g GO in SMFC (0.4-GO SMFC) and adding 0.4 g rGO in SMFC (0.4-rGO SMFC) were 2 and 1.81 times higher than that of adding nothing in SMFC (ordinary SMFC), respectively. The species and compositions of organic matter in 0.4-GO SMFC and 0.4-rGO SMFC decreased significantly and their sludge reduction rate were 3 and 2.2 times that of ordinary SMFC, respectively. Comparing with ordinary SMFC, the maximum power density of 0.4-GO SMFC and 0.4-rGO SMFC was up to 214.09 and 80.52 mW m−3 separately, and their internal resistance decreased by 71% and 48%, respectively. Thus, it can be concluded that GO and rGO had the function of breaking cell and accelerated electrons transporting, so they could greatly promote the sludge reduction and electricity production of SMFC.

Biomass pigments were considered as prospective alternatives to conventional synthetic dyestuffs. In this paper, biocolorants were prepared from tea polyphenols (TP) and were applied in dyeing. Crude enzyme generated by Aspergillus niger was employed to convert tea polyphenols as precursor into pigments via bioconversion, and simultaneously the dyeing of fabrics was achieved in this process. This work demonstrated that pigments prepared were able to dye fabrics with admirable color fastness and meet application requirements. The bio-pigments can be obtained from low-cost reproducible natural resource, tea stalk, which is a kind of tea residual waste. Dyeing with biomass pigments based on bioconversion was presented in this research in which no environmentally hazardous additive was employed to improve dye-uptake and fixation. Therefore, this innovative dyeing technology is a cleaner production method and the dyed fabrics can be categorized as ecological textiles.

This paper verified the feasibility of water hyacinth for the treatment of formaldehyde in wastewater. In laboratory study, water hyacinth exhibited high removal efficiency for input 100–300 ppm formaldehyde. Formaldehyde consumed by water hyacinth root was lifted from the root to stem and then to leaf, and finally it was converted into some acidoid. Particularly, the removal activity was strengthened with enhanced root activity and chlorophyll in water hyacinth in the presence of 0.5 ppm Eupatorium odoratum L. extract. Meanwhile, the growth of water hyacinth was effectively controlled, exhibiting suppressed emergence of sprouts and low growth rate (≤0.032 g.day−1). In pilot study, water hyacinth also exhibited excellent removal ability to formaldehyde during the four recycle experiments and the growth rate was maintained to a low value about 0.023 g.day−1. In conclusion, water hyacinth managed with Eupatorium odoratum L. extract was proposed as a sustainable biotechnical treatment for formaldehyde.

Poly(lactic) acid as a biodegradable polymer has attracted a lot of attentions due to its environmental merits and availability in sufficient quantities for use in the packaging industry. Recycling of poly(lactic) acid and converting it to a new product, instead of a compost material or primary monomer, is an economical and environmental solution. In this paper, recycled poly(lactic) acid fibers melt-spun from disposable package flakes were dyed by using three disperse dyes having different molecular weights and their dyeing behavior and fastness properties have been studied. Dyeing temperature, time and concentration were fully investigated. The results showed that with an increase in the temperature from 80 °C to 120 °C, the amount of dyeing exhaustion rate increased for different disperse dyes. The recycled poly(lactic) acid fibers exhibited a good exhaustion rate in a short time (20 min), low concentrations (0.5% on weight of the fabric) and low temperature (80 °C). The good to excellent washing fastnesses between 4 and 5 were observed for the recycled poly(lactic) acid fibers which were dyed by the three selected disperse dyes under the optimized conditions. Accordingly, it could be considered that the recycled poly(lactic) acid fibers have a great capability to be dyed with low damage, energy consumption, costs and effluent with disperse dyes.

Returning of biomass ash as fertilizer to field plays great role in sustainable utilization of biomass as energy. In the fertilizer application, release rate of nutrients from ash should be controlled to avoid nutrients shock to plants. Making ash into briquettes (granulated ash, pellet, tablet) is a good choice to slow down the release rate of nutrients and prevent dust formation. However, experimental or theoretical analysis of the release behavior of nutrient from ash briquette is scarce. In this paper, different sizes (from Ф6 mm × 2 mm to Ф15 mm × 5 mm) of tablets of biomass ash were made and their nutrient release behavior was investigated experimentally. Results showed that the release rate of potassium in tablet ash was about 1/20-1/60 of that in the powder ash. And that changing tablet size in the normal size range could not decrease the nutrient release rate to the value required by the norm for slow-release fertilizer. Based on the experiments, the mathematical description of the nutrients release process was established and a Matlab code was written for modelling. The theoretical model was validated and parameters required to make slow release fertilizer from the ash were predicted. It showed that, in order to produce slow release potassic fertilizer, much bigger tablet size (from Ф15 mm × 5 mm to Ф210 mm × 70 mm), much lower saturated concentration (from 0.17 to 0.17/142 kg/kg water for potassium), or much smaller effective diffusion coefficient (from 3.2 × 10−10 to 1.6 × 10−12) are necessary. The theoretical model can be generalized to describe the release behavior of any nutrient and can be used in the parameters optimization for producing slow/control-release fertilizer.

The aim of the present paper was to investigate the effect of solids (SRT) and hydraulic (HRT) retention time on Integrated Fixed Film Activated Sludge (IFAS) University of Cape Town (UCT) membrane Bioreactor (MBR). In particular, three different pairs of SRT and HRT values were analysed, namely, Phase I 56 d/30 h, Phase II 31 d/15 h and Phase III 7 d/13 h. The short-term effect of these three SRT/HRT conditions was assessed by analysing several system performance indicators: organic carbon and biological nutrient (nitrogen and phosphorus) removal, biomass respiratory activity, activated sludge filtration properties and membrane fouling. The results showed that the decrease of SRT/HRT had a positive influence on system performance. Specifically, the IFAS-UCT-MBR showed excellent removal of organic matter - highest value (99%) at the shortest SRT/HRT (7 d/13 h). Also, the increase in organic loading rate resulting from the decrease of SRT and HRT led to improved nitrogen removal due to higher N removal by sludge wasting requiring less N removal (as N2) by denitrification. Complete nitrification of influent ammonia was achieved at all three SRT/HRT phases, guaranteed by the presence of biofilm carriers in the aerobic reactor, which ensured a higher media SRT than suspended biomass SRT. The increase of the organic loading rate and decrease in SRT led also to a higher heterotrophic activity as demonstrated by the respirometric batch tests, which is due to the increasing active biomass fraction of the volatile suspended solids as SRT decreases. The SRT/HRT decrease over the three phases resulted in an overall increase of the Extracellular Polymeric Substance concentration, which caused an increase in membrane fouling.

Wood residues generated from orchard maintenance operations represent a serious disposal problem, as well as a valuable opportunity for the bioenergy sector. However, their widespread use as renewable fuel is hindered by uncertainty about crucial quality issues, such as: ash content, ash melting behavior and chemical composition. This paper investigates the main physical and chemical characteristics of pruning residues generated by five of the most common European orchard crops: vine, olive, apple, pear and hazelnut. The results of the analyses are contrasted with the quality specifications set by EU standard UNI EN 14961-1 2010 for forest residues, in the absence of a standard specifically designed for orchard pruning residues. All tested orchard residues biomasses fulfill set specifications, and they also present similar characteristics in terms of ash content, size distribution and heating value. However, the chemical composition of pear and vine residues may raise some concern, due to the high content of nitrogen of the former, and to the high ash, sulfur and chlorine content of the latter. Olive and hazelnut pruning residues seem the most suitable for direct combustion, probably because the origin crops are cultivated less intensively and receive smaller chemical inputs.

Supercritical carbon dioxide was utilized as a sustainable alternative to solvent extraction of waxes from the waste needles of two spruce species, namely Norwegian and Sitka spruce. These extracts were rich in nonacosan-10-ol, an organic compound with hydrophobic properties that lends its use in the preparation of superhydrophobic coatings. The highest crude yields were 1.7% w/w of needles obtained at 400 bar and 60 °C, while nonacosan-10-ol was selectively extracted at 200 bar and 60 °C (8070 ± 91.1 μg/g of needles). Purification of nonacosan-10-ol from the wax extracts was conducted using a simple rapid green recrystallization technique. This yielded a recovery of 44.6% ± 2% and 48.4% ± 2% of the total nonacosan-10-ol from the original crude Sitka (3600 μg/g of needles) and Norwegian wax (1920 μg/g of needles) respectively. Application of nonacosan-10-ol to a filter paper led to the formation of highly hydrophobic surfaces, with preliminary contact angles of up to 149°. This sustainable production method may develop opportunities to valorize forestry waste within a holistic biorefinery.

Wastewater treatment plants (WWTPs) are known to be one of the main and most important sources of microplastics discharge into the environment. Although the occurrence and distribution of microplastics (MPs) in various environments have been extensively investigated, their characteristics in certain environmental matrices remain almost unknown. This paper aims to review strategies for sampling, sample pretreatment, and characterization of MPs detected in WWTPs and sewage sludge. In addition, this paper will review the efficiency of WWTPs in the removal of microplastic particles as well as their fate and implications as a source of toxic chemicals. According to literature, microplastics in water samples are mostly comprised of secondary ones (fibers and fragments) with the main polymers composed of polyethylene terephthalate (PET), polystyrene (PS), polypropylene (PP), and polyethylene (PE). A significant proportion of particles are removed during the initial stages of primary and secondary treatment, while membrane bioreactor (MBR) is found to be the most efficient tertiary treatment technology. The removal rate is affected by the characteristics of MPs such as size, shape, and density. The majority of microplastics eliminated during wastewater treatment are prone to be found in sewage sludge. Thus, billions of MPs are released into the environment via sewage sludge applications each year. Microplastics can also act as a specific layer that adsorbs and transports distinct pathogenic/bacterial taxa assemblages and promotes the persistence of antibiotic resistance genes in wastewater treatment plants. Therefore, the current study provides an overview of recent research regarding MPs occurrence and removal in WWTPs and sewage sludge.

Energy cost contributes to the second largest portion of the starch-processing plants’ expenditure. Therefore, to improve energy efficiencies, CHP systems installed in cassava starch plants are considered. Hence, their energy conversions and efficiencies are investigated. Where, the structure of the plant is modeled, the factors of biogas, power, heat and the biogas distribution ratio are focused; the relationships among those factors are resolved by establishing formulas based on theoretical analysis. Results show: the minimum demand of biogas for 1 t starch product is 134.8 m3, which can produce 704.7–875.6 MJ of electric energy and total 1311.0 MJ of heat for starch production by a CHP-boiler system. The steam produced there can fully satisfy the heat demand under the three strategies, while a minority of excess electricity is available under the strategy 3. The total energy efficiencies of the CHP-boiler system are 70.6%, 70.1% and 67.1% corresponding to the three strategies; those are 8.4%–11.9% more than the efficiency of 58.7% by the original system. The total reduction of CO2 emissions is 2017.1–2508.3t/a for a 200 t/d cassava starch plant using CHP-boiler system; which investment costs 27.24 million CNY in total, and will be pay back in 3.18 years.

Fuel consumption and the drying behavior of lemon verbena leaves were determined in a continuous flow dryer equipped with a solar pre-heating system. In order to reduce the share of fossil fuels and their negative impact to the environment, the total energy during the drying process was supplied using the combination of solar energy (solar water heater) and natural gas. The experiments were carried out at three levels of drying air temperature (30, 40, and 50 °C) and three levels of air velocity (1, 1.5 and 2 m/s). Two working conditions were considered for the drying system: a) solar-gas drying (SGD) mode and b) gas drying (GD) mode. According to the results, in SGD mode, the fuel consumption at drying temperatures of 30 and 40 °C was zero at all levels of the air velocity, while in the GD mode the fuel consumption increased with increasing the inlet air temperature. The highest and lowest essential oil (EO) content was obtained at 40 °C and 2 m/s by 0.60% and at 50 °C and 1 m/s by 0.33%, respectively. The central composite design-Face Centered technique with response surface methodology was used for the optimization of the drying process. The optimum conditions for drying lemon verbena leaves were obtained at drying temperature of 39.54 °C and an air velocity of 2 m/s. In this mode, the fuel consumption was zero, drying time was 131.48 min and EO content was 0.52%.

For environmental reasons, the production of plastic from renewable sources is gaining importance worldwide. In the case of polyethylene made from sugarcane-based ethanol, Brazil, being the world leader in sugarcane production, plays a fundamental role. Nevertheless, the absence of national regulations for monitoring the manufacturing process or verifying the biogenic fraction of what is already on the market raises concerns in Brazil. The main reason for the lack of such regulations is that the only approach fully capable of distinguishing identical chemical compounds of biogenic or fossil origin is the measurement of radiocarbon concentrations using an expensive and time-consuming method. Nevertheless, the measurement of stable carbon isotopes ratios has proven to be an acceptable approach to distinguish between C4 plant-derived plastics and petroleum-derived plastics. The present study compares the potential of the conventional mass spectrometry and radiocarbon accelerator mass spectrometry techniques as tools to determine the biogenic fraction of green polyethylene in Brazil. For plastics derived from either corn or sugarcane sources, δ13C values less negative than −20‰ indicate biofractions of 51% or higher. Other values would indicate the need to follow up to the radiocarbon accelerator mass spectrometry measurement, since it would not be possible to distinguish between lower biofractions and the presence of wheat or soy. The conventional mass spectrometry method can be employed for the preliminary screening of bio-based materials in manufacturing industries, representing a relatively cheap and accessible way of inspecting these products in developing countries.

Flotation tailing is a problematic mining waste, because contains sulphides that exposed to oxidising conditions generate acidic drainage and the subsequent metal mobilisation. In this study, a flotation tailing produced within an integral process for the treatment of polymetallic sulphide ores is cleaned and valorised seeking a better use of natural resources and a lower environmental impact. In this work, bacterial leaching followed by brine leaching is postulated as an alternative to the flotation tailing treatment. Bioleaching destroys pyritic matrix (99% Fe) producing biogenic ferric that can be used as oxidising agent and recycling to a hydrometallurgical process. 80–90% Cu and Zn are dissolved and critical raw materials as Sb, In and Co are recovered. Brine leaching achieves Pb and Ag extractions greater than 96% and generates a solid residue mainly composed of quartz, in which gold that initially was in flotation tailing is concentrated. A clean and easily treatable for gold recovery final residue is obtained. In conclusion, pyrite matrix has been destroyed avoiding the further acid generation and reducing dramatically waste volume, metals have been valorised, and tailing hazardousness has been removed. Therefore, the proposed process is a sustainable alternative for flotation tailing management, reducing the environmental impact, the management costs, and generating income from valorisation of metals and the production of leaching agent.

Expanded polystyrene (EPS) is a synthetic polymer that is widely applicable in the fields of food packaging, equipment protection and civil construction. Aiming to replace EPS, biofoams were developed utilizing mycelia of the macrofungi Pycnoporus sanguineus, Pleurotus albidus and Lentinus velutinus in a medium formulated with sawdust and wheat bran. Sample characterization was obtained by scanning electron microscopy (SEM), thermal analysis and infrared spectroscopy with Fourier Transform; density and compression strength were analysed as mechanical properties. The main results include that the compression strengths of biofoams from P. sanguineus, P. albidus and L. velutinus were 1.3, 0.4, and 1.3 MPa, respectively, which exceed that of EPS (0.4 MPa). The thermal stability of the biofoams was lower than that of EPS; however, they were stable up to 350 °C. Biofoams are denser than EPS, with values of 0.3 and 0.03 g cm−3, respectively. The data obtained for biofoams categorize this material as sustainable substitute for EPS in some applications, while at the same time, reducing the environmental impact caused by sawdust and EPS.

High residual phosphorus in anaerobically digested source-diverted blackwater allows for increased phosphorus recovery through struvite (NH4MgPO4·6H2O) precipitation. Due to the complex matrix of blackwater, recovered products inevitably contain co-precipitates of other wastewater components that have not been well characterized. The potential hazards present include pathogens, antimicrobial resistance genes (ARGs), organic and inorganic compounds. In this study, several important struvite precipitation conditions (pH, Mg2+:PO43− molar ratio and MgCl2 dosing rate) were tested to determine their impact on phosphorus recovery, while taking into account the co-precipitation of enteric bacteria, ARGs and micro- and macronutrients. Results demonstrate that phosphorus recovery efficiency does not correlate to the degree of metal/microbial co-precipitation. Both PO43− recovery and co-precipitates were affected by the operation conditions examined, and the optimal condition for nutrient recovery from blackwater was at pH 9, a 1.5:1 Mg2+:PO43− molar ratio, and a dosing rate of 24 mM min−1. Although previous struvite recovery studies have identified optimal conditions for phosphorus recovery, limited information is available on the process optimization to minimize the potential risks. Downstream application of recovered struvite inevitably contains co-precipitated hazards that if not assessed can result in undesirable public health outcomes. It is necessary to evaluate struvite application and public health exposure to identify key steps that reduce public health impacts. Hence examination of struvite precipitation parameters on enhanced phosphorus recovery, along with co-precipitates, is necessary when considering the public health risk associated with efficiently recovering residual nutrients.

This study focused on the assessment of gas emissions and bioenergy potential of the combustions of bamboo leaves (BL), shoot leaves (BSL) and branches (BB) in the air atmosphere. The main combustion stage of the three residues occurred at between 200 and 600 °C, with three peaks of mass loss. The pattern of mass loss rate was BSL > BB > BL, with BSL having the best combustion characteristic parameters. The main evolved gases were CO2 and H2O at between 200 and 600 °C. Organic gaseous compounds were decomposed in the range of 200–400 °C. Air pollutants were produced in the range of 200–500 °C. N-containing gas pollutants were 0.01–0.1 times CO2, while SO2 was produced in a very small amount. BL produced more gas pollutants than did BSL and BB, while the controls over the gas pollutants should be more concentrated in the range of 200–400 °C. The joint optimizations of derivative thermogravimetry, differential scanning calorimetry, remaining mass, and conversion degree showed 653.2 °C and 5 °C/min as the optimum operational conditions for bioenergy utilization, while BB performed as the best feedstock. Among three iso-conversion methods used to estimate activation energy, Flynn-Wall-Ozawa led to best correlation. The Coats-Redfern method pointed to the second order reaction model (f (α) = (1−α)2) as the most likely reaction mechanism. Overall, the bamboo residues were promising as the environmentally friendly and renewable feedstock. Our findings can provide the basis for bioenergy generation, pollution control, and optimal efficiency when the industrial-scale combustions of the bamboo residues are adopted.

The aim of research is to present favorable operating conditions for the clean syngas production from sugarcane leftover through the gasification process by using AspenPlus™ software. In order to obtain the suitable syngas for liquid fuel production, this process should be integrated with gas cleaning. The simulation was performed by comparing three gasifying agents, i.e., steam, air, and steam-air. To find favorable operating conditions that provide the highest syngas molar flow rate, the effect of operating conditions in gasifier was also examined. In addition, the possibility of syngas production operated under a thermal self-sufficient condition was studied. The gasification results showed that the syngas production significantly increases with the increase of temperature. The proper gasifying temperature for three processes is at 750 °C. When the maximum syngas molar flow rate was considered, it was found that the use of steam (at S/B of 0.6) and steam-air (at S/B of 0.8 and A/B of 0.04) in gasification can achieve this criterion. Both processes can provide syngas molar flow rate as ∼149 kmol/h. However, it was found that thermal self-sufficient operation is possible when air and steam-air are used as gasifying agent. The result indicated that syngas molar flow rate obtained from air gasification (at A/B of 1.309) is more than that from steam-air gasification (at S/B of 0.1 and A/B of 1.375). In order to obtain the cleaner production of syngas, the absorption process with capturing CO2 and H2S was studied via using monoethanolamine (MEA) as solvent. The optimal column pressure is 40 bars and the number of trays equals to 10. To obtain the H2S content below 0.1 mg/m3, the MEA molar flow rates are 325, 450, and 465 kmol/h for steam, air, and steam-air gasification processes, respectively.

This work pioneered the efficient coupling of a leach bed reactor (using a filter medium and no anaerobic sludge) and a continuous stirred-tank reactor (LBR-CSTR) to perform the anaerobic mono-digestion of pig manure. The leachate residue of the pig manure (LR-PM) was dried by a biodrying process. The results revealed that the LBR-CSTR (with ceramsite (C) as the filter medium) showed the best performance (the biogas production was 241.68 ml/g volatile solids (VS), which was 1.24 times higher than that of the control CSTR (CK)), the weight loss of pig manure was the highest (the reduction was 95.83%), and the organic degradation was 86.82% (which was 19.49% higher than that of the CK). The seed germination index (GI) was higher than 50%, and the clogging of the leach bed was overcome. The energy and resource utilizations of pig manure were readily achieved.

In this study, pilot-scale horizontal equipment for zipper tape dyeing in supercritical carbon dioxide (SC-CO2) was designed and successfully constructed. Two horizontal dyeing autoclaves arranged side by side and a color-matching kettle to accelerate the dye dissolution were the two most appealing characteristics of this equipment. The products dyed under the conditions of a temperature of (90 ± 2) °C, pressure of (23 ± 1) MPa, and time of 50 min, presented an excellent color fastness of staining, drying, and wetting, which were all rated at grades of 4–5. The K/S value of the products dyed in SC-CO2 was 6.38, while a value of 5.25 was found in water, even the amount of dyes in the SC-CO2 was lower. The further commercialization of waterless dyeing from pilot-scale studies would have great practical and strategic significance.

This study aimed at verifying the technical feasibility of recovering and reusing several iron-rich residues from the steel production process through the production of briquettes that could potentially be reintroduced as a ferrous source into the converters during the transformation of hot metal into liquid steel. An experimental investigation was carried out on a pilot-scale briquetting plant that implements a pressurised cold agglomeration; 8 mixtures, with contents varying between 60 and 66% Basic Oxygen Furnace (BOF) slag and a maximum of 27% of stock-house dusts and process sludges were tested. In the context of the circular economy, beet molasses was added in varying amounts as a binder, along with cheaper hydrated lime. Experimental results showed how each mixture of recycled materials was able to make briquettes with a high average crushing resistance (73.3 daN for the best mixture, indicated as 2b mix). The X-ray powder patterns, chemical and scanning electron microscopy (SEM) characterization of 2b mix briquettes revealed clean raw residues as well as the presence of limited amount of unwanted compounds such as phosphorus and sulphur, due to the molasses used. By adopting a replacement ratio of 1 between commercial and 2b mix briquettes, a possible safe use of 2b mix briquettes in BOF converters has been estimated. As a lesson, although other investigations need to be carried out (i.e., the reduction disintegration index assessment), briquetting has proven to be effective. It must be intended as an integration rather than a replacement of the input materials generally used in the BOF converter.

In this article, we present a study on the environmental impacts related to cellulase recovery from coffee husks (CH). The environmental impacts of the cellulase recovery process were determined using a comparative attributional life-cycle assessment (LCA) approach. The scenarios were developed according to a novel waste management system in which enzymes were produced during solid-state fermentation (SSF) using CH as a substrate. To date and to our best knowledge, this is the first LCA study applied to a complete SSF process (including downstream stages) at a representative scale. The novelty of this work was the assessment of the complete production process of this technology; namely, the fermentation, extraction, and purification of cellulase. Life-cycle inventory data were obtained from the EcoInvent v3.4 (SimaPro v8.5 software) database and from pertinent pilot-scale experiments. ReCiPe 2016 was used for calculating the environmental impacts. The results showed that most of the environmental impacts of SSF cellulase production were due to electricity consumption. A sensitivity analysis revealed that the lyophilisation step is the major contributor that effects all categories and this impact could be reduced by lowering electricity consumption during the downstream stages. In general, the results pointed out that improvements in the downstream process would help to reduce the SSF environmental impacts and costs.

NOx emissions are the major threat in biodiesel fuelled engines due to fuel bound oxygen and presence of double bonds in their molecular structure. An attempt has been made to reduce the biodiesel NOx emission by varying the saturation level with the help of an approach called “bio-mix”. In this study, bio-mix fuel has been prepared from the waste resources of raw mixture of pig fat and waste cooking oil. Five samples of raw bio-mix oil have been prepared from the different blend ratio of pig fat and waste cooking oil and converted into biomix methyl ester (BMME) samples through transesterification process such as BMME-1, BMME-2, BMME-3, BMME-4 and BMME-5 respectively. All the bio-mix samples have been tested on a single cylinder, light duty stationary diesel engine. Results show that the percentage of saturated fatty acids, cetane number, and calorific values have increased whereas viscosity and iodine values have decreased with an increase in blend ratio. Bio-mix methyl ester fuel shows better combustion, performance compared with waste cooking oil biodiesel (WCOB). Bio-mix methyl esters shows higher in-cylinder pressure and heat release rate which is lower than WCOB at all engine load condition. All the emissions such as NOx, Smoke, CO, and HC have been found lower for BMME compared to WCOB. The non-road diesel engines are also consuming the fossil diesel fuel and hence, this study suggest that bio-mix fuel can be a viable alternative fuel for stationary diesel engines widely used in utility power generation, agriculture and construction equipments.

Solvent recovery and reutilization in bioprocess have great potential to reduce production cost and environmental harm. However, solvent recovery process is often energy-intensive and costly. In this study, we developed an integrated bioprocess for fermentative production of protopanaxadiol (PPD) from ethanol waste recycled in down-stream extraction process, achieving solvent recovery and reutilization in a cost-effective manner. In this integrated process, PPD isolation and purification were achieved by foam separation and resin chromatography, respectively; ethanol solution used as PPD extractant and chromatography eluent was recycled to be reused directly as yeast carbon source for PPD biosynthesis. Notably, in 3 batches of 5 L-fermentation productions, the recycled ethanol could compensate 81.3% of the ethanol used in fermentation. Since the lost PPD during chromatography elution was returned into the next-batch fermentation together with the recycled ethanol, the overall yield of 3-batch production (85.78%) was higher than the yield of single batch production (∼75%). This study demonstrates a promising integrated bioprocess for triterpene compounds production from ethanol waste.

Prevention and mitigation of acid rock drainage (ARD) from mine wastes are crucial for limiting environmental impact. However, preventive measures are often too expensive, potentially harmful to the environment or not applied early enough. This study aimed to test the potential of different secondary raw materials for maintaining a circumneutral pH (6–7) in a sulfide oxidation environment, allowing secondary minerals to form on reactive sulfide surfaces to prevent release of acid, metals and metalloids, and thereby ARD generation. Five materials (blast furnace slag, granulated blast furnace slag, cement kiln dust, bark ash, lime kiln dust) were selected based on their alkaline properties, availability and yearly yield. High sulfidic (>50 wt%, sulfide) waste rock from an active Cu–Zn–Au–Ag open pit mine in northern Sweden was leached in small-scale laboratory test cells under ambient condition for 4–8 weeks before adding secondary raw materials on the surface in an attempt to prevent ARD generation. During 52 subsequent weeks of leaching, the pH and electrical conductivity in the leachate from the waste rock varied between 1.7-4.6 and 2.1–22.8 mS/cm, respectively. All secondary raw materials were able to increase the pH to circumneutral. However, blast furnace slag, granulated blast furnace slag and cement kiln dust were not able to maintain a circumneutral pH for an extended time due to self-cementation or carbonation, whereas bark ash (1 wt%) and lime kiln dust (5 wt%) prevented acidity, metal and metalloid leaching. Materials such as cement kiln dust and bark ash contained elevated concentrations of, e.g., Cd and Zn, but the release of metals and metalloids was generally low for most elements, except for Cl, K and Na, most likely due to salt dissolution.

In this study, wet oxidation of sewage sludge and struvite-precipitation processes were integrated to safely manage sludge and to recover organic acids and phosphorus. To understand this process integration, the effects of temperature, treatment time, and sludge concentration during wet oxidation, and pH and magnesium dosage during struvite precipitation on total suspended solids (TSS), volatile suspended solids (VSS), organic acids production, and phosphorus recovery were investigated. The results showed that TSS and VSS destruction, organic acids production, and phosphorus recovery from sludge into the liquid phase are more sensitive to temperature and time than sludge concentration during wet oxidation. These are novel findings of this work. Furthermore, pH during struvite precipitation had a strong effect on phosphorus recovery. Wet-oxidised sludge was mainly converted to acetic acid, and its concentration increased with increasing temperature and time. These results may be used for optimised operation and revenue generation from wastewater treatment processes when integrated with wet oxidation and struvite precipitation.

Recycled utilization of agricultural waste would make great contributions to the environmental protection and create significant economic benefits. This study focused on the use of rice husk ash (which was abbreviated as RHA), and the metakaolin-based geopolymer (MG) added with RHA were manufactured by alkali activation. The waterproof property and microstructure of samples were investigated and characterized systematically. The SiO2 particles dissolved from the loose layers of RHA could be a potential filler and high active agent, which both played a vital role on the development of enhancement in waterproof property. However, the excessive incorporation of RHA in the synthesis process of geopolymer would also make a side effect on the development of geopolymer comprehensive property. A predictable balance with the optimal property was achieved at the 20% content replacement of MK by RHA. This research would provide a reference for the reuse of agricultural by-product, which is of great value in the realization of diversification in supplementary cementitious materials and recycling in agricultural wastes.

Indian biofuel policy targets large scale utilization of lignocellulosic feedstock. Efficient utilization of the available feedstocks without increasing the pressure on the agricultural land, water and other inputs is essential for overall sustainability. This work focuses on recommending the optimal selection of lignocellulosic feedstock for the Indian biofuel sector considering several sustainability indicators. Six different feedstocks, namely, cotton stalk, rice husk, wheat stalk, sorghum stalk, sugarcane bagasse, and sugarcane molasses, are considered for the production of ethanol using a standardized process. The criteria for selection include life cycle greenhouse gas (GHG) emissions, energy return on investment (EROI), life cycle water use, and land use for ethanol production. Since the decision making criteria show trade-offs, multi-objective linear programming problem was formulated. The model targeted a specific amount of ethanol production without exceeding the feedstock availability, and was solved for different ethanol blending targets. The results recommended complete utilization of sugarcane molasses followed by use of feedstocks such as sugarcane bagasse and sorghum stalk. A strong trade-off was observed between GHG footprint and the other two objectives for EROI 5.08 for base case of 20% blending. Optimal feedstock combination included sugarcane molasses (26.8%), sugarcane bagasse (67%), and sorghum stalk (6.2%) for lowest EROI of 5.08. But for highest EROI of 5.6 the optimal feedstock combination included sugarcane molasses (10.2%), sugarcane bagasse (68.3%), sorghum stalk (6.2%) and cotton stalk (15.3%). The scenarios such as reduced availability of sugarcane bagasse, increase in gasoline demand, effect of data variation gives the additional insights for optimal selection of feedstocks for different blending percentages. The work concluded that sugarcane based feedstock were very critical. Moreover, the proposed approach needs to be systematically used by the decision makers for sustainable biofuel development in India.

Food production and transformation have an increasing impact on the environment. Tools to help the agri-food industry improving its environmental performance whilst increasing the value of the products are highly needed. The present study proposes a new approach to calculate eco-efficiency that goes beyond the production costs, but accounts for the functional value of the foodstuff. Instead of using the monetary unit as the product value, we propose value-based metrics closer to consumer interests, such as content of functional nutrients, taste and abatement of harmful substances. The approach was applied to evaluate the eco-efficiency of de-acidified cranberry juice by two alternative technologies in Quebec: ion-exchange resin process and de-acidification by electrodialysis with a bipolar membrane. Both are compared to non-de-acidified cranberry juice. The parameters chosen to quantify cranberry juice are polyphenol content, product taste, and percentage of harmful acid removed. Results show ion-exchange resin de-acidified juice is less eco-efficient than non-de-acidified cranberry juice for polyphenol content and product taste indicator but shows better results for the removed harmful acid parameter. The electrodialysis with a bipolar membrane technology allows the extraction of organic acids in a usable form. We evaluated their re-utilization in four different contexts showing that this context choice might have a key impact on the eco-efficiency conclusion. The most eco-efficient scenario is the utilization of the removed acid in dried cranberry production with the addition of sugar beet. By using an approach closer to consumers' interests, eco-efficiency results can be more relevant for decision making in the context of cleaner production, particularly when the monetary value is not reliable.

The effects of the microbial community and dynamics on the efficiency of a methanogenic co-digestion system that treats canned coffee processing wastewater and waste activated sludge by means of an anaerobic membrane bioreactor, were investigated and analyzed. The co-digestion system had a chemical oxygen demand (COD) removal efficiency ≥90%, and a COD to methane ratio ≥85%. Phyla Synergistetes, Firmicutes, Proteobacteria and Ca. OP9 were dominant bacteria throughout the investigation, and the main contributors to the hydrolysis and fermentation processes. The degradation paths and functional microbes indicated that genera Caldicoprobacter and Clostridium were the main contributors in the hydrolysis process, while genus Anaerobaculum dominated the acidogenesis and acetogenesis at the most efficient hydraulic retention time (HRT) of 10 d (HRT10). The dominant methanogenesis varied from genus Methanosarcina (71.1%, HRT10) to Methanothermobacter (56.4%, HRT3), indicating a transition from acetic methanogenesis to hydrogen-dependent methanogenesis. Furthermore, a microbial analysis indicated that Acinetobacter was the main contributor to caffeine degradation in this system. This also appears to be the first time that Acinetobacter is reported to be capable of degrading caffeine in the anaerobic condition.

Marine macroalgae (seaweed) has many advantages over terrestrial crops as a source of renewable biomass but is severely underutilised at present, especially within Europe. In particular, macroalgae has elevated poly- and monosaccharide content, making it an ideal feedstock as a heterotrophic fermentation sugar source for the production of higher value chemicals. Recent reports have detailed the suitability of seaweeds as a feedstock for the production of single-cell oils (SCOs) which have application in food, oleochemicals and fuels. It is proposed that a biorefinery system based on the production of SCOs alongside other secondary metabolites, has the potential to provide a sustainable replacement to terrestrial oils such as palm oil. This work therefore evaluates, for the first time, the environmental and economic sustainability of a production process for SCOs from seaweed Saccharina latissima using the oleaginous yeast Metschnikowia pulcherrima. Two alternative fermentation systems were considered, and uncertainties associated with the seasonal variation in seaweed carbohydrate yield and fermentation performance were integrated into the analysis. From an environmental perspective, the work indicates that seaweed derived SCO lipids and fats can be comparable to a terrestrial oil mix, with a potential climate change impact ranging between 2.5 and 9.9 kg CO 2 eq. kg −1 refined SCO. Interestingly and of particular significance, environmental impacts are mainly dominated by energy demand within fermentation and upstream processing steps. From an economic perspective, a break-even selling price for the oil was determined as between €5,300-€31,000 tonne −1 refined SCO, which was highly dependent on cost of the seaweed feedstock. Overall, we demonstrate that key uncertainties relating to seaweed cultivation costs and hydrolysate fermentation at scale result in a large range in values for environmental impact and economic return on investment. Yet even within the constraints and limitations of current knowhow, seaweed already offers a viable proposition for the competitive production of exotic oils similar to cocoa or shea butter in price and nature. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 665992

Biomass energy has been widely regarded as a potential alternative to fossil fuels for abating CO2 emission and gaseous pollutants in iron ore sintering process. In this investigation, the CO-containing flue gas recirculating method was proposed, with its essence of CO reburning to improve sintering performance with high biomass replacement proportion. Results show that biomass fuels replacing more than 20% coke breeze would result in obvious drop of sinter quality due to the shortened high-temperature duration and minerals melting zone. Circulating CO-containing flue gas into sintering bed improved sinter quality significantly as the secondary combustion of CO optimized thermal state. The appropriate replacement proportion of biomass fuel was improved to 40%, and the energy utilization efficiency was increased from 87.25% to 89.62%, which was even higher than that of using coke breeze only. Compared with the case no flue gas circulated, circulating CO-containing flue gas into sintering bed improved the reduction capacity of COx, NO, and SO2 from 18.65%, 26.76%, and 38.15%–31.78%, 45.07%, and 44.51%, respectively. Research findings facilitates the application of high-proportion biomass fuels in practical sintering plants with high energy utilization efficiency as well.

Recent sustainable development goals of food security, environmental protection, material and energy efficiency are the key drivers of the valorization of food waste. In the present work, the production of biosurfactant sophorolipids from several (food) waste streams was investigated, using the non-pathogenic yeast Starmerella bombicola. From a preliminary screening, restaurant food waste emerged as the most suitable feedstock compared to bakery waste, textile waste, used corn oil, animal fat and lipid fraction of hydrolyzed food waste. Restaurant food waste was subsequently used for sophorolipids production in a laboratory-scale bioreactor. Food waste obtained from a local restaurant was subjected to enzymatic hydrolysis for 16 h, yielding a hydrolysate containing about 100 g/L glucose and 2.4 g/L free amino nitrogen. High SL process efficiency was achieved by fed-batch fermentation using the restaurant food waste hydrolysate as the complete batch medium, i.e. without any supplementation of additional medium components such as vitamins, salts, nitrogen or phosphate. Controlled feeding of glucose and oleic acid to the culture was performed after the batch phase. A sophorolipids titer of 115.2 g/L was obtained in a fermentation time of 92 h resulting in an overall volumetric productivity of 1.25 g/L.h. These results achieved for sophorolipids productivity using hydrolyzed food waste are in the same order of magnitude as the reported values using traditional (complex) fermentation media. This indicates the suitability of the developed process using food waste for the advancement of waste-based bio-processes for the production of sophorolipids.

Recycling of iron-bearing waste for stabilizing antimony (Sb) in Waste-to-Energy (WtE) fly ash is a low-cost and sustainable approach. In this work, two laboratory iron–rich residuals (LIR–1 and LIR–2) were collected and their effectiveness for stabilizing Sb in WtE fly ash were evaluated by toxicity characteristic leaching procedure (TCLP) and continuous acid leaching tests. The results of TCLP tests showed that addition of 1.75% LIR–1 and LIR–2 decreased the Sb leaching concentration from 2.04 ± 0.064 mg/L to 0.17 ± 0.004 and 0.15 ± 0.035 mg/L, respectively, which were below the limit value in the standard of 40 CRF 268.40 (1.15 mg/L). Continuous acid leaching tests indicated that the leaching of Sb was pH-dependent, and the dissolution of metal oxides (Fe, Mn and Al) played an important role in controlling the release of Sb from raw WtE fly ash. After LIR treatment, the leaching of Sb was significantly decreased than that from raw fly ash, which was mainly ascribed to the formation of tripuhyite precipitation. These results indicated that LIR could be recycled as stabilizers to immobilize Sb in WtE fly ash, which provided an alternative way for realizing of cleaner production of LIR.

Being a relatively rare mineral, Tamarugite has good coagulation properties. Tamarugite's utilization for coagulation applications has been a great initiative towards the appreciation of this mineral. Aluminium dross, hazardous industrial waste material has been used to produce Tamarugite. The aluminium content present in the dross has been leached into the sulphuric acid. The addition of sodium hydroxide solution into the leached liquor provides for the sodium ions essential for the Tamarugite stoichiometry. It has been found after characterizing the product that the precipitation of Tamarugite by organic solvent furnishes a purer form of Tamarugite. Also, compared to the Tamarugite produced by crystallization, the Tamarugite formed by organic solvent precipitation shows enhanced coagulation performance. To study the reusability of organic solvents for precipitation, ethanol has recycled for the repeated production of Tamarugite. It is observed that the quality of the resultant Tamarugite is maintained. Linking the aspects of industrial waste management and recycling of aluminium dross to water treatment plants, the present article presents a deeper insight into the science behind the synthesis and application of Tamarugite. A holistic view of the article illustrates the alternative method of recycling aluminium dross and enhancement of Tamarugite's applicability in coagulation. The article contributes to environmental management in broadly two ways: industrial waste management and water treatment by coagulation.

A cleaner production of one-part alkali activated cement (AAC) was implemented by mixing chemically treated concrete waste (CTC) with slag. The treatment process was conducted by the addition of NaOH to concrete waste (CoW) at NaOH to CoW weight ratios of 0.2, 0.1, and 0.05 (namely, CTC-1. CTC-2, and CTC-3, respectively), followed by mixing with water and drying. The solidified material was ground then dry-mixed with slag to create one-part alkali AAC powder with fixed particle size. The amount of CTC was varied to achieve constant Na2O content (2 wt %) in all mixtures. The results indicated that the prepared one-part AACs can react with water to yield hardened materials with acceptable compressive strength. Comparing with CTC-1 and CTC-3, the CTC-2 was found to have a dominant impact on the activation of slag hydration, which associated with the higher mechanical properties, lower pore volume, and drying shrinkage. The addition of lead bearing sludge (LBS) to one-part AAC containing CTC-2 resulted in a positive impact on the performance of the prepared cement. According to toxicity characteristic leaching procedures the prepared cement showed a potential effect on solidification/stabilization of Pb-containing-sludge.

The palm oil industry has been one of the major economic contributors for Malaysia over the last decade. While contributing to the country's economic growth, the industry has inevitably produced a significant amount of waste materials which are harmful to the environment. Oil palm boiler ashes (OPBA) generated from boiler in mills are disposed in open landfills which are easily carried away by the wind. The disposed ash pollutes the air while spent earth, when left in landfills, produce a pungent odour. The present work investigated the possibility of refining palm oil with raw OPBA and pelletized OPBA as alternate bleaching adsorbents. The performance of different types OPBA (raw, enhanced and pelletized) was investigated to determine their bleaching efficiencies on carotenoid removal at various operating conditions. Crude palm oil samples were refined with these OPBA and compared with commercial bleaching earth to investigate the final refined oil colours. A final refined oil colour of 4.0R was obtained using 0.05 wt% of enhanced OPBA when bleached at 110 °C for 45 min under constant agitation (300 rpm) and subsequently deodorized at 265 °C for 1 h. This study has indicated that the use of enhanced OPBA which could achieve more than high removal of carotenoid could substitute commercial bleaching earths to produce a comparable final refined oil colour rating. The successful substitution of OPBA to replace the conventional bleaching earth in oil refining could significantly reduce the production cost. This is also a sustainable solution for the edible oil processing industries to mitigate the solid waste and contributes to a cleaner environment.

In the last decades the media have highlighted the ozone depletion as major environmental problem resulting in an increase in ultraviolet radiation (UVR) reaching the earth's surface. Besides the beneficial effects of human exposure to UVR, this radiation is capable of causing damage to human population. The healthy lifestyle is becoming widely accepted by the public, and the UV protection provided by clothing becomes the significant subject of interest of the producers and consumers of textile fabrics. Natural cellulose fibres are commonly used in summer clothing due to their excellent comfort properties. However, these fibres have very poor UV protection ability. In this project, the UV protection property of textile fabrics made of natural and regenerated cellulose fibres have been compared and analysed in order to highlight the potential of hemp fibre for the development of more sustainable and healthy functionalized (UV protective) textile products. A group of homogeneous and blended cellulose textile fabrics were manufactured in a knitwear factory, evaluated in terms of the structure, and spectrophotometrically assessed to indicate their UV protection ability. The knitted fabrics merited sun protection ratings of “good” for pure hemp, through “very good” for viscose containing fabrics to ”excellent” UV protection category for cotton based fabrics. Relatively high values of the Ultraviolet Protection Factor (UPF) of the cellulose materials resulted from the interaction of fibre type, yarn geometry, fabric properties and common processing techniques. The increased UVR transparency of the pure hemp fabric, which resulted from hemp elasticity limitations, overcame by blending with other softer and more elastic cellulose fibres (cotton, viscose). The engineering approach proposed in this study was confirmed as an effective way to create more sustainable (more sustainable resource, pollution prevention, energy and cost savings) textile products with high level of UV protection at the knitting production stage avoiding the use of any additional mechanical and chemical treatments. These results revealed that the future application of hemp fibres in textile products with high added-value are promising. A co-ordinated effort of different subjects of the agro- and textile-industry production chain need to continue so as to overcome the limitations associated with hemp production and fibres properties.