Search

To evaluate the effect of brown-rot fungi Oligoporus placenta and earthworm Eisenia fetida on decomposition of paper mill sludge, the paper mill sludge was mixed with cow dung in 0, 25, 50, 75, and 100% proportions and changes in physicochemical quality of waste mixtures was carried out for 28 days. All waste mixtures were treated with: Setup-I (E. fetida), Setup-II (O. placenta) and, Setup-III (E. fetida + O. placenta). A decrease in total organic carbon, C/N ratio and cellulose but an increase in total kjeldhal nitrogen, total phosphorus, total potassium and pH was recorded. The paper mill sludge in 50–75% proportion in feedstock showed the better results and rate of mineralisation were in order: Setup-III > Setup-I > Setup-II. The proportion of CD has direct role in waste mineralisation. The microbial population (bacterial, fungal and actinomycetes) and earthworm biomass were also high in Setup-III, suggesting the influence of brown-rot fungi on paper mill sludge humification. Results indicate that fungal inoculate in vermicomposting was effective in decomposing cellulose-rich industrial sludge.

Aeration, as a process in pulp and paper wastewater treatment, uses the greatest share of the energy. Therefore, if the energy efficiency of the treatment has to be improved, the focus must be on aeration. A key finding from the trials conducted for this paper, with effluent from a paper and pulp mill, was that the oxygen transfer coefficient could be doubled and the chemical oxygen demand could be decreased by 25%, if the effluent was pre-treated with 30 mg/l of aluminium coagulant (equivalent to 9.4 tonnes per day of AVR to 20000 cubic metres of effluent). Decrease in oxygen requirement implies decreases in aeration energy use. Pulp and paper mill effluents are not as biodegradable as municipal sewage, and the improvement in oxygen transfer properties of the effluent will have a positive influence over a longer period of time in the biological treatment. If the sludge is digested anaerobically, pre-treatment will also result in doubling the potential for methane generation. A holistic analysis of modifications to processes entails a study of the economic and environmental consequences as well. While the economic aspect is beyond the scope of this paper, only the net global warming as an environmental impact category has been studied, by taking recourse to specific emission coefficients. Of the four dosages of ferric aluminium sulphate considered in this analysis, the net greenhouse gas emissions are the least – 426 kg carbon dioxide equivalent per day when the daily consumption is 9.4 tonnes.

Different heating processes were applied to pretreat the pulp and paper mill sludge to enhance the hydrolysis stage. Hot air oven, autoclave, microwave and water bath were used for comparison. Chemical analyses exposed that all the pretreatment methods have shown improvement in solubilisation of organic matter. Among the pretreatments studied, heat transfer through hot air (80 °C for 90 min) mode had the highest impact on sludge solubilisation. There was an increase in cellulose (P = 0.0096), acid soluble (P = 0.0053) and insoluble lignin (P = 0.0012), but decrease in hemicellulose (P = 0.0009) content after pretreatment. The XRD and FT-IR spectroscopic characterisation shows the development of aliphatic, unsaturated and carbonyl carbon functionalities in the pretreated samples at higher severities. FESEM picture also confirms the change in structure after pretreatment. Thus, pretreatments contribute to disruption of the lignocellulosic structure making the cellulose easily accessible to acidogenic microorganisms.

This work assesses six different agricultural residues with the aim of finding alternative raw materials for a soda semichemical pulping process: stems of bell and chili pepper ( Capsicum annuum ), broad bean ( Vicia faba ), asparagus ( Asparagus officinalis ), pea ( Pisum sativum ), and okra ( Abelmoschus esculentus ). Pulping yields higher than 60% (m/m) were obtained, except for pea stems (43%). The drainability of all the pulps, expressed as the Schopper-Riegler index (oSR), had values of over 70 oSR. The Kajaani analyses of the fibers showed acceptable fiber lengths in all cases (0.64–0.92 mm), but on average shorter than the lengths of pulps from a commercial fluting paper (Old corrugated Container, OCC), that was found to be 1.27 mm. Handsheets of paper were produced both with the pulps under study and with mixtures of these pulps with OCC pulp. Several properties were measured to assess the use of the new fibers in a paper for cardboard production. The property showing the greatest differences was the Gurley porosity, ranging from 25 mL/min (asparagus) to 1300 mL/min (broad bean). Of the six residues tested, the okra residue fiber showed better properties than the commercial paper fiber (Concora Medium Test indexes: 1.5 N m 2 /g and 1.1 N m 2 /g respectively, Burst Indexes: 2.3 kPa m 2 /g and 1.7 kPa m 2 /g, respectively), yielding similar mechanical properties to those of high quality fibers obtained from miscanthus ( Miscanthus giganteus ). Broad bean residue could also be a promising raw material, though its properties are not as good as okra’s.

Worldwide pulp and paper industry is recognized as a serious threat due to the discharge of various toxic contents present in its effluent to the surrounding environment. To combat this challenge, the role of oleaginous yeast to utilize the pulp and paper industry effluent for the integrated toxic contents removal and sustainable biodiesel production were undertaken. Oleaginous yeast Rhodosporidium kratochvilovae HIMPA1 was used as a model organism for its unique ability to utilize pulp and paper industry effluent as a culture medium and accumulate high quantity of triacylglycerol or neutral lipids as large size lipid droplets of 4.56 ± 0.24 μm within its cellular compartment. The maximum cell dry weight (13.87 g/L) with total lipid yield of 8.56 g/L was obtained after 144 h of cultivation. Data showed significant reduction in effluent toxic components i.e. color, 89%; lignin, 94.27%; phenol, 99.60%; biochemical oxygen demand, 77.36%; total dissolved solids, 84.59%; and chemical oxygen demand, 94.22%. Fatty acid methyl esters profile revealed high quantity of long chain monounsaturated fatty acids (45.43%) and polyunsaturated fatty acids (15.91%) that improves biodiesel quality under low temperature condition in terms of low cold filter plugging point along with good oxidative stability and cetane number as per American Society for Testing and Materials D6751-02 and European Committee for Standardization - EN14214 guidelines.

Recycling of waste paper was investigated with the aim of boosting the use of recycled materials and reducing the impact of waste paper on environment. Commercially important cyanoethyl cellulose product from waste paper was synthesized successfully through a cycle of chemical treatments. Waste paper was functionalized to cyanoethyl cellulose in an alkaline heterogeneous reaction environment with acrylonitrile under different reaction conditions with respect to degree of substitution. The variables studied were: Sodium Hydroxide and acrylonitrile concentration, reaction time and temperature for alkalization and cyanoethylation. All the cyanoethyl cellulose products were assessed for solubility, degree of polymerization and degree of crystallinity. The optimum conditions for cyanoethyl cellulose synthesis comprised of 8.34 M/anhydro glucose unit aqueous sodium hydroxide concentration, 30 °C alkalization temperature, 60 min alkalization time, 70 M/anhydro glucose unit acrylonitrile concentration, 60 min reaction time for cyanoethylation and 50 °C cyanoethylation reaction temperature. The optimized cyanoethyl cellulose product was characterized with fourier transform infrared spectroscopy, proton magnetic resonance spectroscopy, X-ray diffraction and scanning electron microscopy. This investigation helped to find the proper cleaner production approach towards sustainable environment management by synthesizing valuable cyanoethyl cellulose product and demonstrated that waste paper have the capacity to produce upgraded and high quality cyanoethyl cellulose for variety of applications.

High pressure laminate has a key role at the protection of wood-based panels. Borax and recycled papers can be used for production of high pressure laminate which may impart the multitude effects. The readily availability of waste papers and borax may be a useful alternative to expensive papers with high quality, and also can compensate the strength losses of recycled papers. The recycled paper and borax are relatively inexpensive and environmentally friendly, and this results the production of not only a cleaner product but also provides an excellent performance against applied load, humidity and high temperature. In this study, three types of waste papers including newsprint, writing and paperboard were first recycled to be used for production of high pressure laminate. Phenol formaldehyde and borax were utilized to improve the strength and fire retardancy of high pressure laminate. Bending resistance, flame resistance and water absorption of high pressure laminate samples were tested. The results of the experiments showed that high pressure laminate made of recycled newspaper and borax had a superior performance when compared to samples that made from writing paper and paperboard. For example, an increase up to 1.4 times was observed in the bending resistance. The mixing of borax with resin increased the strength of high pressure laminate at 95 percent confidence level. The amount of water absorption after 2 h, bending resistance, glowing time and char length of high pressure laminate with recycled newspaper and borax were equal to 14%, 41 mNm, 37 s and 0.7 cm, respectively. The bending strength of coated particleboard with this overlay increased up to 1.5 times. High pressure laminate produced from recycled paper and borax was introduced as an environmentally acceptable product.

The aim of this study is to enhance the use of agro-industrial byproducts and to address the environmental concerns by a novel method of co-production of thermoplastic composites with a solid residue constituting biorefinery. Accordingly, the reuse of 10–30 wt. % solid residues (SRH) from the enzymatic hydrolysis of recycled paper sludge (PS) in the production of thermoplastic composites with polypropylene (PP) was investigated. Thermal properties, water absorption, tensile strength and morphology of the prepared composites were evaluated. Higher thermal stability, rougher and wetter surface, and characteristics of a brittle material were observed in PP-SRH composites in comparison to the pristine PS-PP composites and the neat PP. The water absorption increased with increasing amount of SRH, but in lower proportion compared to other common raw materials used in the preparation of composites. Use of SRH resulted in similar or better properties compared to the composites made with the unhydrolyzed paper sludge, suggesting that SRH has potential for recycling and utilization as filler in the development of thermoplastic composites.

Industrial productivity is often judged solely by the primary product's marketability, while opportunities for secondary products derived from process by-products are often overlooked. In paper mills, large volumes of moisture-rich paper mill residuals (cellulose sludge) are produced, for which commercial use is currently difficult. Port Hawkesbury Paper LP, Port Hawkesbury, Nova Scotia, produces over 7 t/hr of waste sludge with a seasonally-dependent dryness ranging from 25 to 38% (w/w). Various chemical or mechanical dewatering options exist; however, knowledge of the unique sludge composition and properties is essential to predicting how the product will react under each method. Sonication, Fournier rotary press technology, freeze/thaw cycling, and gravity drying were among the dewatering opportunities briefly explored outside of the chosen method, acidification. Notably, many industries utilizing dewatering technologies may not be producing value-added by-products, while geographic and climatic placement may limit processes which are possible for others. In the present study examining enhanced end-use value, further dewatering occurred through a comparative in situ experiment contrasting sulfuric acid and ferric sulfate acidification (direct acid injection into sludge). While both proton donors acidified the sludge and decreased moisture content, sulfuric acid was the more cost-effective option, yielding an ∼4% increase in dryness, with commensurate economic and environmental benefits.

This work presents the results in the field of materials engineering, and they are related to recycling of paper production waste sludge particles at amounts of 10 wt% and 20 wt% in tall oil polyol-based rigid polyurethane foam with and without tris (1-chloro 2-propyl) phosphate flame retardant. The impact of both systems on physical and mechanical properties, thermal stability, fire resistance and ignitability is studied. Paper production waste sludge particles filled rigid polyurethane foams display better fire performance thus resulting into reduction of the emission of CO2 and CO as well as reduction in average heat release rate. Scanning electron microscopy has shown that paper waste sludge particles and tris (1-chloro 2-propyl) phosphate together act systematically, and synergism between two materials may be observed. It is as well determined that paper production waste sludge particles reduce thermal conductivity by approx. 15% for polyurethane foam with paper production waste sludge particles and by approx. 13% for polyurethane foam with paper production waste sludge particles and conventional flame retardant. Moreover, the substitution of tris (1-chloro 2-propyl) phosphate, petroleum based polyol and hydroflurocarbons with 10 wt% and 20 wt% of PPWS particles, tall oil polyol and water reduces carbon dioxide emission by 60.8% and 39.6%, respectively, contributing to cleaner production of rigid polyurethane foam.

Although the environmental performance of the paper industry has drastically improved since the nineties, Western manufacturers still refuse to reuse agricultural waste. Moreover, papermakers make extensive use of poorly biodegradable polyelectrolytes which are toxic to fish. With this in mind, we suggest pulping lignocellulosic residues by sulfur-free processes, decrystallizing cellulose, and introducing positively charged functional groups with the goal of partially replacing conventional cationic polymers. Functionalization of pulps from orange tree trimmings, rapeseed stalks and wheat straw was carried out with different concentrations of (3-chloro-2-hydroxypropyl)trimethylammonium chloride (CHPTAC). When the mole ratio of CHPTAC to anhydroglucose units was 4, cationic fibers reached charge density values over 0.2 meq/g after 40 or 60 min of reaction. Then, we tested the performance of these fibers in papermaking, using titanium dioxide, whose zeta potential is negative, as filler. Opacity of lightweight paper was raised to 90%, surpassing a conventional cationic polyacrylamide (CPAM), while the increase in brightness (from 37.8% to 41.9%) was not as good as that achieved with CPAM. Even if residues cannot replace wood, chemical modifications of them can result in valuable cationic fibers, making synthetic polyelectrolytes less necessary.

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.

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.

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.

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.

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.

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.

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.

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.

Graft copolymer of natural rubber (NR) and styrene to used as a blend with styrene-butadiene for green tire can be produced via three techniques: emulsion polymerization (EP), electron beam irradiation (EB), and gamma ray irradiation (GR). Products from all techniques had similar cross-linking properties; leading to similar mechanical properties. Therefore, producing the graft copolymer using less resources is the best choice as it is a cleaner production. This paper compared the environmental impact assessment of these three production processes. SimaPro version 7.3 software using Eco-indicator 99 method for environmental impact assessment was used throughout this study. The functional unit (FU) used was 100 g of grafted rubber product, with the considered system boundary starting from raw materials for the production of a specified product and continuing to the end of copolymerization processes (cradle-to-gate). The results indicated that, at the laboratory scale, the EB technique had the largest contribution of environmental impacts, followed by EP and GR techniques. However, operating at the maximum capacity led to an overall reduction of all impacts. The reduction was improved by 86.32% for EB and by 60.5% for GR. However, production by EB still contributed the highest overall environmental impact, while GR contributed the least. In decreasing order of significance, the main impacts of EB were resources (R), human health (HH), and ecosystem quality (EQ). The essential factors which caused these impacts were, in decreasing order of significance, the usages of electricity, NR, and styrene. Therefore, GR method was the choice for scaling up the green production process in both saving the electricity usage and for improvement in the environmental impacts.

Poor sanitation due to improper treatment of human excreta, and energy scarcity are global problems with only partial solutions. Thus, feasible conversion of human excreta into safe, reusable “products” and renewable energy could be advantageous. The research objectives were to study the properties and major chemical processes occurring during hydrothermal carbonization of raw human excreta with typical solids content, as well as exploring potential use of the resulting hydrochar and aqueous phase. Human excreta (often considered as black water) were hydrothermally carbonized in a set of nine 50-mL laboratory batch reactors under a range of severities, a single parameter obtained from a coalification model that represents the combination of temperature and time. Three temperatures (180, 210 and 240 °C) and reaction times (30, 60 and 120 min) were used. The physicochemical characteristics such as yield, elemental composition, organic matter and calorific value of the hydrochar (solid phase) were studied. Aqueous phase was characterized for carbon, nitrogen, macro and micronutrients composition. In addition, the potential use of the hydrochar and aqueous phase were studied. There was high correlation between severity factor and carbon content (R2 = 0.95) and calorific value (R2 = 0.89). Hydrochar yield decreased with increasing severity from 69 to 56%. Calorific values increased from 24.7 to 27.6 MJ/kg, falling within the calorific range of sub-bituminous coal. The aqueous phase demonstrated high nitrogen concentration, reaching up to 8178 mg/L total nitrogen, while N:P:K ratios were similar to those of commercial fertilizers. Pilot scale experiments resembled the results found in laboratory scale experiments for both hydrochar and aqueous phase and fitted the regression curves obtained from the severity factor. It is postulated that hydrothermal carbonization of human excreta could potentially serve as a sustainable sanitation technology with a closed-loop cycle approach while recovering energy and nutrients.

A novel degumming approach by using steam treatment is proposed to minimize water pollution and consumption in silk wet processing. Sericin removal of Bombyx mori silk fibers was carried out with pressurized steam. The degumming ratio, fine structure and physical properties of the degummed silk fibers as well as energy efficiency were investigated to elucidate the degumming effects of steam treatment. Compared to the conventional neutral soap and sodium carbonate (Na2CO3) degumming methods, sericin can be removed by steam treatment without any chemicals, and the degumming ratio as well as physicochemical properties of the degummed silk fibers maintained at a desirable level. Energy efficiency and cost analysis showed that steam degumming is more energy-efficient and economical than the conventional chemical degumming methods. Results showed that steam treatment is a feasible silk degumming method with the benefits of reduction in water pollution and energy consumption.

Textile dyeing effluent has been the focus of considerable research because of its adverse effects on aquatic biota. Here, we present the first comprehensive study of a combined permanganate and ozone (KMnO4 O3) technique to treat different kinds of textile dyeing wastewater. We investigated the effects of process parameters on TOC and COD removal and the toxicity of the wastewater after KMnO4 O3 treatment. The synergistic mechanism involved in the KMnO4 O3 process is also discussed. The results indicate that KMnO4 O3 treatment is efficient in treating many kinds of textile dyeing wastewater. The TOC, COD, and toxicity were reduced by approximately 70%, 80%, and 34.4–95.5%, respectively, using a KMnO4 dosage of 1.5 mM, an O3 dosage of 10 mg/L, a pH value of 7, and a reaction time of 30 min. Furthermore, biodegradability was increased to 0.33–0.68. The combined use of KMnO4 and O3 provided synergetic and complementary advantages. On the one hand, oxidation of pollutants on suspended solid surfaces and in the aqueous phase was enhanced by the stirring action of O3 molecule bubbles. On the other hand, small molecular organic compounds and fine particles were coagulated by KMnO4 and its intermediate oxidations. X-ray photoelectron spectroscopy results indicate that the valence state of manganese changed after KMnO4 O3 treatment, and the manganese intermediate catalysing O3 process contributed to the removal of 20% of COD and 19% of TOC. It was therefore determined that the KMnO4 O3 treatment is a promising method for use in the treatment of textile dyeing wastewater.

Recycling of petrochemical by-products is important for environmental protection and sustainable utilization of resources. In this study, petrochemical by-product was analyzed and used for the first time as a cost effective frother in flotation separation of molybdenum to replace terpineol. A significant improvement in molybdenum recovery was achieved by replacing terpineol with petrochemical by-products as frother. Properties of the petrochemical by-product and terpineol solutions, such as foaming, bulk rheology, and foam stability, were investigated through surface tension and rheological measurements. The properties of the petrochemical by-product solution are generally better than that of terpineol. In addition, results obtained in bench-scale flotation showed that the recovery of molybdenum substantially improved by 2.5% in the locked-cycle tests when the concentration of the petrochemical by-product was 100 g/t. Industrial tests showed that the molybdenum recovery obtained by using petrochemical by-products increased by 2.55% which can lead to about 6918192 RMB (1001113 USD) net profit per year. Therefore, these encouraging results suggest that petrochemical by-products can effectively be utilized in mineral processing plants as frothers, and interestingly, Jinduicheng Molybdenum Industry Co., Ltd, China is one that started to use it in industrial production by replacing terpineol.

A floating phytobed system based on plants of Chrysopogon zizanioides and Typha angustifolia (Consortium CT) was effective in the removal of Scarlet RR Dye (150 mg/L) and a textile effluent, with rates of 89 and 87%, respectively, within a 60-h period, which demonstrates a higher elimination rate than an individual plantation. In addition, the treatment of textile effluents with the floating phytobed linked to microbial fuel cells was enhanced in terms of color reduction, chemical oxygen demand, biological oxygen demand, total dissolved solids and total suspended solids up to 82, 75, 75, 67 and 70%, respectively. Moreover, it produced a power of 0.0769 W/m2 at current density of 0.3846 A/m2. Terminal restriction length polymorphism community analysis documented 37 new genera which have a probable role in efficient treatment as well as power generation. Induction in the activities of oxidoreductase, high performance thin layer chromatography and gas chromatography-mass spectroscopy analyses of treated Scarlet RR dye confirmed the biotransformation. Toxicity evaluated on gill histology of Lamellidens marginalis and inter simple sequence repeat marker assessment confirmed the decreased toxicity of Scarlet RR after phyto-transformation.

Producción Científica, Sugar beet pulp (SBP) is the major by-product in sugar industry. To make profit out of this undervalued residue, the FASTSUGARS process was proposed as a solution, combining the advantages of supercritical water as hydrolysis medium with very short reaction times in the so-called ultrafast reactors. Operating at 390 °C, 25 MPa and reaction times between 0.11 and 1.15 s it was possible to convert SBP into sugars and to obtain a lignin-like solid fraction. The highest yields of C-6 and C-5 sugars (61 and 71% w/w, respectively) were obtained at 0.11 s with the lowest yield of degradation products. The solid product obtained at 0.14 s was thoroughly analyzed by acid hydrolysis, TGA and FTIR analysis to prove its enhanced thermal properties and aromaticity. The FASTSUGARS process demonstrated being a versatile and promising technology to be integrated in the future biorefineries., Ministerio de Economía, Industria y Competitividad (Project CTQ2013-44143-R and CTQ2016-79777-R)

A parametric study employing Taguchi's design of experimental technique was conducted to produce a value added novel biochar mix from three different origin feedstock and evaluate the effect of process parameters on biochar quality. Three feedstocks sourced from different origins (macroalgae: Sargassum sp, agricultural waste: rice husk and lignocellulosic waste: pine wood) were mixed in a definite proportion and pyrolyzed following the L4 experimental layout. Results indicated that temperature and mixing ratio were the most influential contributing factor. A temperature of 500 °C and 70% algae mix was the optimum condition to get an enhanced biochar in terms of thermal stability, aromaticity, pH balance, ash content and yield. Among the 4 Taguchi combination char S3 stands out as the best condition that resulted in high aromaticity, 40% high ash content, highly alkaline pH (10.3), 1–2% higher nitrogen and sulfur content. Potential application of biochar in agronomy as a soil ameliorant and/or in contaminant remediation as an adsorbent is suggested.

The manufacturing of energetic compounds (explosives), such as 1,3,5-trinitroperhydro-1,3,5-triazine (RDX) and 3-nitro-1,2,4-triasol-5-one (NTO), generates large volumes of wastewater containing organic pollutants, which are also rich in nutrients, mainly nitrogen. These wastewaters are subject to regulatory compliance and require treatment prior to their release into local water bodies. An approach is proposed to recover nutrients and water from wastewaters prior to treatment by growing microalgae with the aim to reduce the energy footprint of the munitions production facility by producing algae-based biofuels. In order to assess the feasibility of implementation of the proposed approach, ten different fully characterized untreated wastewaters with various levels of organic and inorganic carbon and nitrogen content were assessed for microalgae toxicity using Scenedesmus obliquus ATCC® 11477 as target microorganism. Toxicity experiments were performed in microplates for six days at 25 °C, 120 rpm orbital mixing speed, under a 14:10 h light: dark photoperiod, and 68 μmol photons/m2s of light intensity. The results indicate that the majority of the wastewater streams assessed could be used as nutrient media with no pretreatment while only three of the streams required chemical treatment due to their high growth inhibition characteristics. From the toxicological results obtained, a site specific mixture prepared by blending of the different untreated waste streams was tested for Scenedesmus obliquus growth. It was observed that this microalga can reach 5 × 107 cells/mL over six days of incubation in the wastewater mixture containing up to 24 mg/L RDX and 28 mg/L NTO. This strain exhibited similar growth patterns in the wastewater mixture as compared to the control sample, suggesting the potential feasibility of using untreated, energetic-laden industrial wastewater along with carbon dioxide [CO2 (atmospheric or flue gases)] for microalgae biomass production.

In order to reduce solid content and to recover value from municipal solid waste materials, laboratory-scale batch hydrothermal deconstruction tests were carried out under subcritical wet oxidation conditions. Treatments of the selected solid waste materials (plastics, timber, tyres, cardboards, and sanitary items) were carried out at a temperature range from 240 to 280 °C with initial pressure of 35 bar oxygen. A substantial solid reduction was observed for the wastes through the wet oxidation deconstruction process, which breaks down the physical structure of the waste materials and segregates the solids into useable process outputs, such as acetic acid. At 280 °C, more than 90% of total suspended solids were successfully reduced and at least 1500 mg/L of acetic acid was produced for each individual material. The mixture of materials representing a non-recyclable municipal solid waste stream produced approximately 2930 mg/L of acetic acid. Soluble chemical oxygen demand showed different trends for different materials due to competing effects of solubilisation and oxidation. The high concentrations of acetic acid product offer opportunities for recovery and re-use if effectively managed therefore such a process can provide a significant commercial and environmental benefit.

Combustion of Mazut in power plant generates sulfur oxides (SOx) and nitrogen oxides (NOx) that need to be controlled in accordance with the European standard. Most of the pollutant removal methods are effective in removing only one contaminant but not both SOx and NOx. In this work, a combined approach is studied to simultaneously control SOx and NOx from combustion of Mazut fuel. This combined approach is consisted of the Mazut Nano-Emulsion usage instead of regular Mazut, as well as, wet flue gas desulfurization or FGD system installation. The wet FGD system removes the SOx by 80.3% but has no influence on NOx. The water content equals to by 10% of Mazut volume is used to synthesize the Mazut Nano-Emulsion at optimum performance. The dimensions of fuel droplet are in nano scale (63.7 nm in width and 123 nm in diameter). The Mazut Nano-Emulsion usage removes the NOx and SOx by 30.8% and 42.2%, respectively. The approach of Mazut Nano-Emulsion usage and wet flue gas desulfurization leads to simultaneous reduction of SOx and NOx in accordance with the European standard. Results show that the combined approach decreases the SOx and NOx 79.8% and 78.3%, respectively that satisfied the European standard.

In order to minimise the environmental, social and economic impacts caused by the mining activity, this work proposes the use of iron ore tailings from tailings dams (IOT) as pigment in the production of a paint for buildings – the Sustainable Paint. The waste originates from the mining activity in the state of Minas Gerais. For this work, it was used in its raw state, subjected only to drying and lump breaking. In addition to IOT and water, four types of binders were tested: polyvinyl acetate (PVA) resin (in the form of ordinary white glue), acrylic resin, hydrated lime for painting and high early strength Portland cement. Binder contents ranged from 0% to 50% over the mass of IOT. For the evaluation of the mixtures, four main parameters were used: cost, colour homogeneity, abrasion resistance, and durability to external exposure, using the colour difference methodology ΔE (Delta-E). The results of binder evaluations were compared among themselves and with conventional paints from a brand recognised by the Brazilian Association of Paint Manufacturers. The Sustainable Paint presented reddish colour; suitable opacity; satisfactory results regarding durability at a significantly lower cost. In general, the blends with IOT, especially those using PVA as binder, have proved to be promising alternatives for paintings prepared in situ. It is noticeable the wide potential of use of this pigment by communities affected by iron ore tailings dams throughout Brazil and worldwide.

Centrifugal mother liquid (CML) is a typical poorly biodegradable organic wastewater generated during the production of polyvinyl chloride (PVC). A method of treating PVC centrifugal mother liquid by a high efficiency internal circulation aerobic biofilm reactor (four reactors lined up together) is presented in this study. The optimized technique was tested and evaluated in a lab and in a plant scale system. The effect of chemical oxygen demand (COD) removal efficiency was studied under different hydraulic retention time (HRT): 40, 20, 17, 14 and 12 h, respectively. Considering the efficiency and removal rate, the best HRT was 14 h. At HRT of 14 h, the average volume loading was 0.326 kg COD/(m3∙d). During the product shift from TL-1000 to TL-800 (two kinds of PVC products with different polymerization degree), the treatment efficiency of the system was not affected. Compared with the plant scale system, the results showed that in the lab setup the removal rates of centrifugal mother liquid of TL-1000 (total organic carbon (TOC) = 70–75 mg/L) and TL-800 (TOC = 20 mg/L) were 90%–95% and 80%–90%, respectively. While in the plant scale system, the removal rates of centrifugal mother liquid of TL-1000 and TL-800 were 80%–90% and 65%–80% (effluent TOC 7.5–12 mg/L), respectively. Biofilm formation by the microbial reproduction as well as intensive filamentous bacteria settlements were observed.

Palm Oil Mill (POM) effluent is the primary discharge from the industrial clarifiers during POM processing and a potential substrate for methane production. However, due to its rich content of sulfate components, the initial fermentation phase of anaerobic digestion is highly acidifying which leads to severe performance losses, digester's instability, and even culture crash. This study introduces a new reactor design, shear-loop anaerobic contact stabilization (SLACS) system to enhance the methane productivity of POM substrate. The treatment profiles, including the influence of feed COD/SO42− ratio, pH and sulfide inhibition was examined for the shear-loop anaerobic bed (SLAB) and the anaerobic plug flow (APF) units of the SLACS system which functions as a dissimilatory sulfate reduction phase and a methanogenic phase, respectively. Experimental observations indicated that methane (CH4) production, COD and sulfate removal were influenced by the feed COD/SO42− ratios. In addition, the performance of the one-stage domesticated digestion of POM substrate was compare with the two-stage domesticated SLACS system. During two-stage domestication, methane productivity was 256 mL g−1 VS, a 32% methanogenic proficiency higher than that of the one-stage digestion. The SLAB unit had great advantage in averting the toxic inhibitory effect of sulfide and non-ionized H2S accumulation on the microbial community structure and the two-stage SLACS system could proficiently enhance the substrate utilization efficiency and energy recovery from POM substrates, thus enhancing methanogenesis.

In the nitrophosphate process of fertilizer production, rare earth elements (REE) can be recovered as a REE phosphate concentrate. In this process, after digestion of apatite in concentrated nitric ...

The treatment of recalcitrant bio refractory pollutants especially common in wastewater emanating from the tannery industries is a major challenge to the industries due to the absence of an efficient treatment technology, high operational costs as well as in view of the stringent rules imposed by the various environmental and governmental regulatory bodies. This study reports the degradation of organic pollutants present in tannery waste effluent (TWE) using hybrid hydrodynamic cavitation (HC) such as HC + ozone (O3), HC + hydrogen peroxide (H2O2) and HC + Fenton's reagent. HC treatment alone caused a reduction of 14.46% chemical oxygen demand (COD), 12.60% total organic carbon (TOC), 10.01% total dissolved solids (TDS) and 34.82% total suspended solids (TSS) of the TWE samples at the optimum inlet pressure of 500 kPa within 120 min. It also caused an increase in biodegradability index (BI) value from 0.33 to 0.43 indicating increased biodegradability, whereas dilution of the TWE samples did not enhance the HC process efficiency. HC combined with O3 was effective as COD and TOC reduction increased to 26.81% and 17.96% respectively at the optimum loading of 7 g/h of O3. HC combined with H2O2 also significantly enhanced the degradation efficiency to a maximum of 34.35% COD and 19.71% TOC reduction due to the enhanced generation of hydroxyl radicals. However, HC combined with Fenton's process was found to be the most efficient hybrid process for the treatment of TWE at a maximum reduction of 50.20% COD and 32.41% TOC respectively at FeSO4.7H2O/H2O2 ratio of 1:3 (w/w). The requirement of H2O2 per g of COD reduction for HC + Fenton reduced to 1.95 g/g compared to the requirement of 3.02 g/g for HC + H2O2 process. Moreover, HC + Fenton's treatment increased the BI value from 0.28 to 0.46, which is an increase by 64% compared to an increase by 30% using HC alone. These hybrid techniques enhanced the BI of treated TWE and therefore may be used as a pre-treatment tool by integrating into existing biological treatment units in the conventional effluent treatment plants, in order to cause enhanced degradation of highly bio-recalcitrant organic pollutants. Other enhanced benefits include higher rate of mineralization of organic matter with lower cost of treatment. Hybrid HC + Fenton was the most energy efficient approach than HC process with a 75% reduction in the energy requirement and 56% reduction in treatment cost per mg of COD reduction of TWE.

The anaerobic digestion of municipal sewage was studied at psychrophilic temperatures (19 °C and 17 °C) in three up-flow anaerobic sludge bed reactors (UASB). A pulsed feeding system was operated for 430 d, during which different hydraulic retention time (HRT) (6, 8, 10, 12, 14, 18, 24 and 36 h) were tested. Granulation of the sludge was observed under the pulsed feeding strategy and a 6 h HRT. Low hydrolysis rates were obtained at HRTs lower than 10 h, as a result of an increased solids accumulation inside the reactor. An HRT of 14 h was identified as the most suitable HRT under the studied temperatures (19 °C and 17 °C), with methane yields of 136 and 117 mL CH4/g of removed chemical oxygen demand (CODremoved), respectively.

Spent lithium-ion batteries have caused global concern owing to their rich resource metal content and high potential for polluting the environment. In the present study, a green, efficient, and simple process was developed to recycle and detoxify Li, Mn, Cu, Al, Co, and Ni from spent lithium-ion mobile phone batteries using adapted Aspergillus niger. The adaptation of Aspergillus niger to heavy metals improved the production of organic acids and the leaching efficiency of metals compared to unadapted fungi. Moreover, it decreased the time required to enter the logarithmic phase and increased the speed of acid production. In the presence of spent lithium-ion battery powder, gluconic acid was the main lixiviant produced by the adapted fungi. At a pulp density of 1% (w/v), the adapted Aspergillus niger leached 100% Li, 94% Cu, 72% Mn, 62% Al, 45% Ni, and 38% Co. The results of SEM, FTIR, XRD, EDX, and mapping analyses of the original spent battery powder and bioleached residue confirmed the effectiveness of fungal metabolites to leach the metals of spent lithium-ion mobile phone batteries.

Anaerobic co-digestion of solid wastes with activated sludge for biogas production is an alternative and effective cleaner process of energy production from waste matter. This study comprehensively evaluated the suitability of Tea Powder Waste as an alternative co-substrate for higher biogas production. Biochemical Methane Potential analyses were performed on the anaerobic co-digestion of carbon-rich organic solid waste and Tea Powder Waste with the presence of Methanogens in activated sludge. The process parameters for the co-digestion of organic waste with Tea Powder Waste were optimized in order to achieve higher biogas production. Biogas producing reactors, with the organic wastes and methanogens activated sludge, were maintained under a mesophilic temperature (35 ± 2 °C) for 60 days retention period. The influence of various process parameters on the production of biomethane were analyzed. The optimized feed ratio of 1:2:1 (FFV: TPW: MAS) showed higher methane yield. Nitrogenous compounds present in Tea Powder Waste increased the methane production by four folds. The co-digestion of wastes showed 65% yield when compared to 40% yield as in mono-digestion of wastes.

Gravity-driven membrane (GDM) filtration is a promising technology for decentralized drinking water treatment due to its low energy requirements and simple operation. The reduced flux observed in GDM systems relative to other membrane treatment techniques remains a vital obstacle to their wider application. With the goal of further improving membrane flux and permeate quality, three simple and practical technologies have been examined as pre-treatments for GDM systems, (i) slow filtration with granular activated carbon (GAC), expected to remove both biodegradable and non-biodegradable contaminants, (ii) slow filtration with modified fiber ball (MFB), expected to promote biodegradation of organic compounds and (iii) microfiltration (MF), expected to reject suspended substances and particles. Results indicated that stable permeability increased by approximately 230%, 150% and 100% in GDM systems employing GAC, MFB and MF pre-treatments compared to the control. The dissolved organic compounds (DOC) were removed by approximately 60% and 30% in GAC/GDM and MFB/GDM, while MF/GDM and GDM control were not effective at DOC removal. Correlations between the stable flux and extracellular polymeric substances (EPS) concentration (R2 > 0.9) indicated that reduction of EPS should be responsible for the flux improvements. Tracing the fate of florescent foulants illustrated that the EPS was mainly secreted/converted by the microbes colonizing within the bio-fouling layer of the GDM system. During long-term filtration, assimilable organic compounds (AOC) which can serve as nutrients for the growth of microbes within the bio-fouling layer were efficiently consumed (>50%) by the biological pre-treatments. This reduction in AOC was linked with a reduction in the growth/activity of bacteria within the bio-fouling layer of GDM system and a reduction in EPS accumulation. Overall, biological pre-treatments can significantly enhance the flux and water quality produced by a GDM system without significantly increasing the operation and maintenance. These improvements in flux and water quality can hopefully spark wider adoption of GDM as an economical and environmentally-friendly technology for decentralized drinking water treatment.

Generally the exhaust dyeing process utilizes a large amount of energy, time and high liquor ratio. On the contrary, the microwave irradiation can be used for the exhaust dyeing that consumes less energy and less time. In this research, the environmental friendly technique, the microwave irradiation, is used to dye cotton fabric at lower liquor ratio through the exhaust dyeing process and it is compared with the conventional dyeing method. The exhaustion percentage, fixation percentage, and color strength values have been measured and a suitable recipe is obtained. It is found that the microwave technique facilitates the process by minimizing the dyeing time and maximizing the exhaustion percentage, fixation percentage, and color strength values. Furthermore, the microwave technique is considered as a green technique and higher exhaustion and fixation percentages indicate that there is comparatively less residue dye in the effluent. XRD and SEM tests also performed to analyze whether the microwave has affected the morphological structure but from the results, there is not a considerable difference observed. Finally, the colorfastness tests have been carried out and compared with the conventionally dyed samples and the results are almost the same for both techniques. Hence the microwave technique is providing almost the same quality product by using less time with the environment friendliness.

A new synthetic route was developed to create an azo-based reactive disperse dye containing the vinyl sulphonyl reactive group. This dye was used to colour wool and cotton fibres using scCO2 as the dyeing medium. The optimum dyeing process was carried out with water pre-treatment at 90 °C and 140 bar during a 60 min dyeing time. Under optimal conditions, which are relatively moderate for supercritical dyeing processes, the dyed wool fabrics produced uniform dyeings with high colour strength and fastness properties. These wool dyeings provided good colour strength and fixation properties (fixation of 99.4%). Cotton also showed good colour strength results. Crucially, the process did not produce any dyeing effluent. Furthermore, there is a potential to modify a wide scope of disperse dyes using the thiol group via this synthetic method without the need for further purification.

Oxy fuel combustion technique has been in practice since last three decades powered mainly by coal or other fossilized fuels. A similar technique was applied to biomass thermochemical conversion keeping in consideration zero carbon and renewability features of biomass. Experimental investigation of combustion characteristics of lignocellulose based biomass including maize stalk, wheat straw, rice husk and groundnut hull has been carried out in this study. Objective was to determine the behavioral changes in fuel inherent nitrogen during combustion and its distribution between elemental nitrogen (N2) or nitrogen oxides (NOx) after the combustion. Approximately isothermal conditions with temperature range from 700 °C to 1200 °C and various oxidizer atmospheres comprised of mainly oxygen with corresponding nitrogen or carbon-dioxide gases were opted for the experimental work. Results revealed that average 78% relative NOx reduction efficiency for four selected biomasses (81.69% maize stalk; 68.69% wheat straw; 88.64% rice husk & 72.99% groundnut hull) was achieved under 21% O2/79% CO2 atmosphere over the corresponding 21% O2/79% N2 atmosphere. Through enhancing O2 ratio in oxy biomass combustion atmosphere i.e. 30% O2/70% CO2 and comparing NOx reduction efficiency with its corresponding 30% O2/70% N2 atmosphere; an average relative NOx reduction efficiency of 80.49% i.e. (maize stalk: 78.94%, wheat straw: 79.11%, rice husk: 88.60%, groundnut hull: 75.30%) was attained. It was concluded that oxygen played key role in achieving satisfactory reduction in NOx emissions.

Dilute acid (DA) pretreatment results in the formation of inhibitory compounds and pseudo-lignin along with the burden of unnecessary materials like ash, extractive, lignin or their condensed products that reduces the conversion efficiency of cellulose to monomeric sugar. Indian Oil Corporation Limited (IOCL) has developed a modified pretreatment (MP) in order to reduce the enzyme dosage during ethanol production. This method uses extraction of biomass in water and varying alkali concentration of 0.2, 0.4 and 0.5%, prior to pretreatment as a strategy to reduce the enzyme dosage and improve the ethanol yield. The environmental and economic impact of these MP scenarios in comparison with conventional pretreatment (CP) is studied. The ethanol production increases from 218 to 267 L using MP. The introduction of extraction step prior to DA pretreatment fulfills the objective of reducing enzyme dosage by 23–39%. However, overall life cycle assessment (LCA) results revealed that performance of MP2, MP3 and MP4 is on a negative side in all the environmental impact categories as compared to CP due to the use of alkali, where a huge amount of emissions are released during the production stage. Overall, MP1 using water as a media for extraction is the most environmentally suitable pretreatment process for ethanol production. Life cycle costing (LCC) results showed that cost of 1 L ethanol production could be lowered down from 0.87 to 0.70 United States Dollar (USD) using MP1 scenario. From an environment and economic perspective, it is recommended to use only water as an extraction media for biomass, as this can reduce the enzyme dosage, emissions and cost.

This study was focused on the application of various chemical and electrochemical advanced oxidation processes (AOPs/EAOPs) as a polishing step for the remediation of a textile wastewater, concerning its discharge into the environment and its reuse in the textile industry. The textile wastewater was previously subjected to biological treatment, clarification and filtration. The following processes were compared: hydrogen peroxide (H2O2) photolysis with ultraviolet C (UVC) radiation (H2O2/UVC), anodic oxidation (AO), AO with electrogenerated H2O2 (AO-H2O2) and AO-H2O2 with UVC radiation (AO-H2O2/UVC). Furthermore, the influence of H2O2 concentration on the H2O2/UVC process and the influence of current density on the AO-H2O2/UVC process were evaluated. The efficiency of the AOPs/EAOPs was assessed in terms of decolorization and mineralization. The decolorization ability of the various processes up to 25–30 min of reaction could be arranged in the following sequence: AO > AO-H2O2/UVC ≈ H2O2/UVC > AO-H2O2. For treatment times above 25–30 min, the AO-H2O2/UVC and H2O2/UVC processes provided higher decolorization than the AO process. Complete color removals were found, contrasting with a maximum mineralization of 39%, thereby indicating the presence of recalcitrant non-colored organic compounds. The German color discharge standards were achieved after 5–9 min of reaction for all processes, whereas the Brazilian color discharge limit was reached after 10 min of reaction for the AO process, 20 min for the AO-H2O2/UVC and H2O2/UVC processes, and 35 min for the AO-H2O2 process. The feasibility of using the recycled textile wastewater in textile processing was proved for scouring, bleaching and dyeing processes, taking into account hydrophilicity, color difference and whiteness index. The treatment times required for reuse purposes applying the H2O2/UVC process were equal or higher than the ones necessary for discharge purposes: 45 min for scouring, 20 min for bleaching, and 30 min for dyeing.

Bleaching technology by ozone dissolved in water offers alternative measures to prevent pollution in the textile industry for sustainable development at organizational and economic levels. In this paper, jeans fabric was treated with ozone injected in water combined with ultrasound and H2O2. Effectiveness of Fenton process regarding dye degradation was also tested with confirmation of hydroxyl radicals detected by fluorescence and electron paramagnetic resonance (EPR) spectroscopy. Results showed that individual ozone was more effective regarding the bleaching of the jeans samples than the hydroxyl radicals especially when coupled with ultrasound. The mechanical action of ultrasonic cavitations enhanced the diffusion of ozone through the fabric which increased the degradation of the indigo dye. The fading degree of samples treated with ultrasound and 100 g/Nm3 of ozone for 60 min in acidic condition reached 64.49 which gave a full bleach appearance. Scanning electron microscopy (SEM), ultimate tensile strength and fastness tests were performed in order to evaluate the effect of such treatment on the cotton fabric. The said tests proved that moderated concentrations of ozone caused no damage to the cotton fiber and results were very close to those obtained with ordinary bleaching processes.

Coal fly ash (CFA) is an industrial by-product derived from coal combustion in thermal power plants. This abundant and low cost by-product is generally reemployed as an additive in the building industry. This work explores the possibility of recovering CFA as an adsorbing material for the removal of anionic surfactants dissolved in water, on the basis of data about concerning its embodied energy. Indeed, Although the CO2 footprint of CFA and activated carbon is comparable, CFA shows an extremely lower embodied energy with respect to activated carbon, the most used widely used material for surfactant removal. Surfactant are widely used in several detergents products, and enter into the environment through the discharge of sewage effluents. In this paper, Sodium Dodecyl Sulfate (SDS) is used as a model surfactant. Upon careful optimization of the CFA/SDS mass ratio, it was found that CFA is able to remove SDS from water with efficiency up to 96%. SDS adsorption onto the CFA surface was investigated and results point to a three-step mechanism, which stops with the final formation of a CFA supported SDS bilayer. There are two main results: first, the first one in the era of raw materials scarcity, the choice of to investigate the employ employment of a material in terms of its embodied energy must be considered; second, the second result this work opens new perspectives in the field of anionic surfactant removal.

Reactive dyeing of cotton generates a great deal of coloring wastewater containing residual dyes, electrolyte, alkali, and other auxiliaries. Especially for the effluent from the first/initial spent dyeing bath, it may be comprised of as high as 60% of the initial dye dosed, 30–90 g/L of sodium chloride or sodium sulfate, and plenty of sodium carbonate, making it to be the most contaminative effluent among the entire reactive dyeing process. This paper presents a new alternative to regenerate the waste effluent from the first spent dyeing bath through catalytic ozonation with novel catalysts for reuse of the effluent in successive dyeing. Two novel ozonation catalysts, mesoporous carbon aerogel and its supported cobalt oxide nanoparticles, were successfully prepared and used in catalytic degradation of residual dyes in waste effluents with ozone. Degradation efficiency was determined by both decolorization and chemical oxygen demand removal. The result showed novel catalysts could improve both of these two targets. For chemical oxygen demand removal, carbon aerogel supported cobalt oxide strikingly enhanced the efficiency by 30% on the whole comparing to ozonation alone (approximately 50%) without the catalyst. Waste effluents after catalytic ozonation were thereafter reused in successive dyeing in the same process. It has been validated that the waste effluent was successfully regenerated and can be additionally reused twice without sacrificing fabric quality, which cannot be realized in ozonation alone. Color difference of the fabric dyed with the regenerated effluent was within the acceptable tolerance, and excellent levelness and equal colorfastness had also been achieved. This is probably the first study to investigate the feasibility of regenerating highly polluting dyeing effluents for reuse by catalytic ozonation with carbon aerogel materials. With novel catalysts, it could be speculated that catalytic ozonation is a promising technology for in-situ regeneration of waste effluents in textile dyeing plant for reuse.

The interest in nanocellulose made from woody biomass has been growing rapidly; however, detailed studies on the environmental performance of nanocellulose have only been reported on a few occasions. To fulfill this gap, the environmental performance of nanofibrillated cellulose fabricated from thermo-groundwood (removal of extractives, lignin and hemicelluloses, TEMPO oxidation and homogenization processes were included) was evaluated by means of a Life Cycle Assessment. The results show that the purification process contributes more than 95% of the impact. It is associated with a relatively high consumption of electrical energy and ancillary chemicals, i.e., cyclohexane and acetone. The global warming potential of 1 kg of nanofibrillated cellulose is as high as 800 kg CO2 equivalents. Even in the case that in addition to the extractives and the hemicelluloses also lignin is considered as a potentially valuable co-product, and the latter takes over some of the burden, the impact of nanofibrillated cellulose remains relatively high, at around 400 kg CO2 equiv. per kg of nanocellulose. While the primary energy consumption is around 19.000 MJ per kg of nanofibrillated cellulose, or 10.100 MJ in the case that the lignin is considered as a potentially valuable co-product. The study also had a methodological goal, i.e., the impact indicators were calculated using the three most relevant evaluation methods: ILCD/PEF, CML 2001 and ReCiPe 2016. These three methods show similar results for the impact on global warming and acidification. However, in the case of impacts on some other indicators, significant deviations in the obtained impact scores were observed with respect to the results for the three methods. Taking into account the background data of the methods, ReCiPe 2016 was found to be the most up-to-date method and can currently be considered as the preferable Life Cycle Impact Assessment method.