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Water pollution and the unsustainable use of fossil fuel derivatives require advanced catalytic methods to clean waters and to produce fine chemicals from modern biomass. Classical homogeneous catalysts such as sulfuric, phosphoric, and hydrochloric acid are highly corrosive and non-recyclable, whereas heterogeneous catalysts appear promising for lignocellulosic waste depolymerization, pollutant degradation, and membrane antifouling. Here, we review the use of sulfonated graphene and sulfonated graphene oxide nanomaterials for improving membranes, pollutant adsorption and degradation, depolymerization of lignocellulosic waste, liquefaction of biomass, and production of fine chemicals. We also discuss the economy of oil production from biomass. Sulfonated graphene and sulfonated graphene oxide display an unusual large theoretical specific surface area of 2630 m2/g, allowing the reactants to easily enter the internal surface of graphene nanosheets and to reach active acid sites. Sulfonated graphene oxide is hydrophobic and has hydrophilic groups, such as hydroxyl, carboxyl, and epoxy, thus creating cavities on the graphene nanosheet’s surface. The adsorption capacity approached 2.3–2.4 mmol per gram for naphthalene and 1-naphthol. Concerning membranes, we observe an improvement of hydrophilicity, salt rejection, water flux, antifouling properties, and pollutant removal. The nanomaterials can be reused several times without losing catalytic activity due to the high stability originating from the stable carbon–sulfur bond between graphene and the sulfonic group.

Solid wastes from domestic, industrial and agricultural sectors cause acute economic and environmental problems. These issues can be partly solved by anaerobic digestion of wastes, yet this process is incomplete and generates abundant byproducts as digestate. Therefore, cultivating mixotrophic algae on anaerobic digestate appears as a promising solution for nutrient recovery, pollutant removal and biofuel production. Here we review mixotrophic algal cultivation on anaerobic waste digestate with focus on digestate types and characterization, issues of recycling digestate in agriculture, removal of contaminants, and production of biofuels such as biogas, bioethanol, biodiesel and dihydrogen. We also discuss applications in cosmetics and economical aspects. Mixotrophic algal cultivation completely removes ammonium, phosphorus, 17β-estradiol from diluted digestate, and removes 62% of zinc, 84% of manganese, 74% of cadmium and 99% of copper.

Background The ring expansion technique is a non-standardized material testing used to evaluate round tubes’ mechanical properties such as burst pressure and stress-strain behavior, however, this technique has limitations such as lack of suggested specimen geometry, strain measurement technique, and friction coefficient(s) estimation. Objective This study primarily aims to evaluate the stress-strain property in the hoop direction for seamless pipes with a further correlation with the tensile stress-strain curve. Moreover, investigating the specimen’s geometry effect on the results was also considered throughout the study. Methods Experimental, simulation, and analytical techniques were carried out and through their conjunction, it was applicable to estimate hard-to-measure coefficients, identify and evaluate new correction factors, and validate the simulation and analytical results. Results Experimental strain measurements were performed by derived analytical equation rather than an external measuring device, novel evaluation of the hoop stress correction value (K) was performed by the comparison between experimental and simulation work, in addition to a convenient similarity between the standard tensile test and the non-conventional proposed technique results. Conclusion The ring expansion test is a promising technique to evaluate the seamless pipes' burst pressure, stress-strain behavior, and other mechanical properties. Furthermore, the authors recommend future work regarding estimating both pressure dissipation factor (α) in terms of friction coefficients and hoop stress correction value (K) in terms of ring’s geometry.

Circular agriculture and economy systems have recently emerged around the world. It is a long-term environmental strategy that promotes economic growth and food security while reducing negative environmental consequences. Anaerobic digestion (AD) process has a high contribution and effective biodegradation route for bio-wastes valorization and reducing greenhouse gases (GHGs) emissions. However, the remaining massive digestate by-product contains non-fermented organic fractions, macro and/or micro-nutrients, heavy metals, and metalloids. Direct application of digestate in agriculture negatively affected the properties of the soil due to the high load of nutrients as well as the residuals of GHGs are emitted to the environment. Recycling and valorizing of anaerobic digestate is the main challenge for the sustainable biogas industry and nutrients recovery. To date, there is no global standard process for the safe digestate handling. This review described the biochemical composition and separation processes of anaerobic digestate. Further, advanced physical, chemical, and biological remediation's of the diverse digestate are comprehensively discussed. Moreover, recycling technologies such as phyco-remediation, bio-floc, and entomoremediation were reviewed as promising solutions to enhance energy and nutrient recovery, making the AD technology more sustainable with additional profits. Finally, this review gives an in-depth discussion of current biorefinery technologies, key roles of process parameters, and identifies challenges of nutrient recovery from digestate and prospects for future studies at large scale.

The physical and chemical effects of the hydrothermal, acid and alkali pretreatment methods of rice straw were investigated to be used in volatile fatty acids (VFAs) production through two-stage anaerobic fermentation. The effects of two-stage acid production and fermentation process parameters of different pretreated straws under the fermentation temperature conditions of 35°C, 55°C, and 70°C were analyzed. The results showed that The hydrothermal, 2% HCl, and 1% Ca(OH)2 increased the specific surface area of the rice straw by 12.20%, 52.62% and 37.81%, respectively. The alkali pretreatment increased the macro and mesopores of the rice straw while the hydrothermal and acid pretreatments increased the small and micropores. The primary fermentation did not affect significantly the infrared spectrum peaks of pretreated rice straw. The rate and total VFAs production was enhanced significantly after the 1% Ca(OH)2 pretreatment compared with 2%HCl and hydrothermal pretreatments respectively. Based on the initial mass of 100 g raw straw, when pretreated with 1% Ca(OH)2 and fermented at 35°C, the primary and the secondary acid production were 12.23 g and 16.54 g, respectively, and the total acid production was 28.77 g. This study provides an optimum condition for the best pretreatment and process parameters for acidogenic biorefinery of rice straw for enhanced VFAs production.

Deposition and precipitation of paraffin wax in pipelines are major problems in the production, transfer, storage, and processing of crude oil. To prevent complete clogging, it is necessary to minimize and remove deposited wax in pipelines and tubing. Significant research has been done addressing the mechanisms of wax formation and its composition. In this review, the status of research and perspectives on the occurrence and characterization of the paraffin wax that forms in crude oil developing wells and pipelines has been critically reviewed. Several approaches for detecting paraffin wax and managing wax formation damage during oil recovery were discussed. This review also highlighted the effects of temperature and crude oil type on wax formation.

A total of twenty bacterial cultures were isolated from hydrocarbon contaminated soil. Of the 20 isolates, RAM03, RAM06, RAM13, and RAM17 were specifically chosen based on their relatively higher growth on salt medium amended with 4 % crude oil, emulsion index, surface tension, and degradation percentage. These bacterial cultures had 16S rRNA gene sequences that were most similar to Ochrobactrum cytisi (RAM03), Ochrobactrum anthropi (RAM06 and RAM17), and Sinorhizobium meliloti (RAM13) with 96 %, 100 % and 99 %, and 99 % similarity. The tested strains revealed a promising potential for bioremediation of petroleum oil contamination as they could degrade >93 % and 54 % of total petroleum hydrocarbons (TPHs) in a liquid medium and soil amended with 4 % crude oil, respectively, after 30 day incubation. These bacteria could effectively remove both aliphatic and aromatic petroleum hydrocarbons. In conclusion, these strains could be considered as good prospects for their application in bioremediation of hydrocarbon contaminated environment.