An environmental management industrial solution for the treatment and reuse of mussel wastewaters

Renewable Carbon Materials as Electrodes for High-Performance Supercapacitors: From Marine Biowaste to High Specific Surface Area Porous Biocarbons

Waste, in particular, biowaste, can be a valuable source of novel carbon materials. Renewable carbon materials, such as biomass-derived carbons, have gained significant attention recently as potential electrode materials for various electrochemical devices, including batteries and supercapacitors. The importance of renewable carbon materials as electrodes can be attributed to their sustainability, low cost, high purity, high surface area, and tailored properties. Fish waste recovered from the fish processing industry can be used for energy applications and prioritizing the circular economy principles. Herein, a method is proposed to prepare a high surface area biocarbon from glycogen extracted from mussel cooking wastewater. The biocarbon materials were characterized using a Brunauer-Emmett-Teller surface area analyzer to determine the specific surface area and pore size and by scanning electron microscopy coupled with energy-dispersive X-ray analysis, Raman analysis, attenuated total reflectance Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy. The electrochemical characterization was performed using a three-electrode system, utilizing a choline chloride-based deep eutectic solvent (DES) as an eco-friendly and sustainable electrolyte. Optimal time and temperature allowed the preparation of glycogen-based carbon materials, with a specific surface area of 1526 m² g^-1, a pore volume of 0.38 cm³ g^-1, and an associated specific capacitance of 657 F g^-1 at a current density of 1 A g^-1, at 30 °C. The optimal material was scaled up to a two-electrode supercapacitor using a DES-based solid-state electrolyte (SSE@DES). This prototype delivered a maximum capacitance of 703 F g^-1 at a 1 A g^-1 of current density, showing 75% capacitance retention over 1000 cycles, delivering the highest energy density of 0.335 W h kg^-1 and power density of 1341 W kg^-1. Marine waste can be a sustainable source for producing nanoporous carbon materials to be incorporated as electrode materials in energy storage devices.

An Interpenetrating Polymer Network Hydrogel Based on Cellulose, Applied to Remove Colorant Traces from the Water Medium: Electrostatic Interactions Analysis

The main objective of this work was the removal of eosin Y and green malachite from an aqueous medium by using a cellulose-based biodegradable interpenetrated network (IPN). The IPN was obtained by the sequenced synthesis method. In the first step, cellulose was crosslinked with epichlorohydrin (ECH). In the second step, the obtained gels were swollen in a reactive mixture solution, which was based on the monomers 2-hydroxyethyl methacrylate (HEMA) and 1,6- hexanediol diacrylate (HDDA). After this, swelling equilibrium was reached through the gels' exposition to UV radiation. An infrared spectroscopy (FTIR) was used to analyze the bond stretching, which confirmed the IPN's formation. The swelling kinetics in aqueous mediums with different pH values showed a high swelling at a basic pH value and a low response in neutral and acidic media. The IPNs showed an improvement in water uptake, compared to the networks based on PHEMA or cellulose. The IPN was used to remove dyes from the water. The results showed that a high percentage of green malachite was removed by the IPN in six minutes of contact time. The experimental results were confirmed by the docking/modeling method of the system (IPN/Dye). The different physical interactions between the IPN and the dyes' molecules were investigated. The interactions of the hydrogen bonds with malachite green were stronger than those with eosin Y, which was in good agreement with the experimental results.

Sustainable alternatives for by-products derived from industrial mussel processing: A critical review

The industrial mussel processing generates significant quantities of waste. Nearly 30% of one metric tonne of processed mussel is finally destined for human consumption. Regardless of the mussel commodities, an important quantity of waste is concentrated at several sub-processes, such as input reception, washing and declumping shells, and mussel meat extraction stages, or by means of the rejection of mussels only due to a size characteristic criterion established by the target market. Despite the main segregated waste comprising shells, byssus threads, residual meat and wastewater, a heterogeneous composition must be taken into account, since much of the solid waste is commonly gathered and compacted for landfill transportation purposes. This paper reviews the sustainable management strategies for mussel by-products, addressing their limitations for an industrial implementation to obtain value-added products. It is concluded that, although there is a well-known diversity of waste sustainable management alternatives, several proposed products (e.g., collagen, bio-adhesives, biopolymer, and adsorbent for pollutants) still remain in a potential framework, circumscribed into laboratory results, subject to an optimization process, to a validation by industrial pre-scale trials, or even limited by the associated production costs. Future researches should focus on reducing the uncertainties linked with their technical-economic feasibility for an industrial scale development.

Bioconversion of Fish Discards through the Production of Lactic Acid Bacteria and Metabolites: Sustainable Application of Fish Peptones in Nutritive Fermentation Media

In the current work, we study the capacity of 30 peptones obtained by enzyme proteolysis of ten discarded fish species (hake, megrim, red scorpionfish, pouting, mackerel, gurnard, blue whiting, Atlantic horse mackerel, grenadier, and boarfish) to support the growth and metabolite production of four lactic acid bacteria (LAB) of probiotic and technological importance. Batch fermentations of Lactobacillus plantarum, L. brevis, L. casei, and Leuconostoc mesenteroides in most of the media formulated with fish peptones (87% of the cases) led to similar growths (quantified as dry-weight biomass and viable cells) and metabolites (mainly lactic acid) than in commercial control broth (MRS). Comparisons among cultures were performed by means of the parameters obtained from the mathematical fittings of experimental kinetics to the logistic equation. Modelling among experimental and predicted data from each bioproduction was generally accurate. A simple economic assessment demonstrated the profitability achieved when MRS is substituted by media formulated with fish discards: a 3-4-fold reduction of costs for LAB biomass, viable cells formation, and lactic and acetic acid production. Thus, these fish peptones are promising alternatives to the expensive commercial peptones as well as a possible solution to valorize discarded fish biomasses and by-products.

Introduction of one efficient industrial system for turpentine processing wastewater reuse and treatment

Wastewater treatment is one important issue for turpentine plant and more wastewater generated by greater turpentine processing will prevent its further development. To solve this issue without extra place and new equipment, one industrial system for reuse and treatment of turpentine processing wastewater was introduced for the first time. For wastewater reuse, the technology was simple and easy to control that after neutralization by lime and absorption with activated carbon (optional, mostly not necessary), the wastewater could be reused for turpentine processing. After reuse, the wastewater was further treated by a biological system. During long-term application of wastewater reuse in this plant, it showed little influence on the products performance (mainly acid value) and final wastewater COD. Base on above advantages, the plant could decide when for wastewater drainage, and thus the amount of wastewater was reduced greatly. For the biological treatment, the COD of wastewater could be degraded to suitable level stably and the wastewater after treatment could be applied for daily life in the plant. Overall, considering the cost, operation, and performance, the whole system shows great potential and possibility of industrial application and therefore can be applied widely in the turpentine processing industry.

Enzymatic Processes in Marine Biotechnology

In previous review articles the attention of the biocatalytically oriented scientific community towards the marine environment as a source of biocatalysts focused on the habitat-related properties of marine enzymes. Updates have already appeared in the literature, including marine examples of oxidoreductases, hydrolases, transferases, isomerases, ligases, and lyases ready for food and pharmaceutical applications. Here a new approach for searching the literature and presenting a more refined analysis is adopted with respect to previous surveys, centering the attention on the enzymatic process rather than on a single novel activity. Fields of applications are easily individuated: (i) the biorefinery value-chain, where the provision of biomass is one of the most important aspects, with aquaculture as the prominent sector; (ii) the food industry, where the interest in the marine domain is similarly developed to deal with the enzymatic procedures adopted in food manipulation; (iii) the selective and easy extraction/modification of structurally complex marine molecules, where enzymatic treatments are a recognized tool to improve efficiency and selectivity; and (iv) marine biomarkers and derived applications (bioremediation) in pollution monitoring are also included in that these studies could be of high significance for the appreciation of marine bioprocesses.

Removal of tricaine methanesulfonate from aquaculture wastewater by adsorption onto pyrolysed paper mill sludge

Tricaine methanesulfonate (MS-222) has been widely used in intensive aquaculture systems to control stress during handling and confinement operations. This compound is dissolved in the water tanks and, once it is present in the Recirculating Aquaculture Systems (RASs), MS-222 can reach the environment by the discharge of contaminated effluents. The present work proposes the implementation of the adsorption process in the RASs, using pyrolysed biological paper mill sludge as adsorbent, to remove MS-222 from aquaculture wastewater. Adsorption experiments were performed under extreme operating conditions, simulating those corresponding to different farmed fish species: temperature (from 8 to 30 °C), salinity (from 0.8 to 35‰) and different contents of organic and inorganic matter in the aquaculture wastewater. Furthermore, the MS-222 adsorption from a real aquaculture effluent was compared with that from ultrapure water. Under the studied conditions, the performance of the produced adsorbent remained mostly the same, removing satisfactorily MS-222 from water. Therefore, it may be concluded that the produced adsorbent can be employed in intensive aquaculture wastewater treatment with the same performance independently of the farmed fish species.

Spatial Characteristics and Driving Factors of Provincial Wastewater Discharge in China

Based on the increasing pressure on the water environment, this study aims to clarify the overall status of wastewater discharge in China, including the spatio-temporal distribution characteristics of wastewater discharge and its driving factors, so as to provide reference for developing “emission reduction” strategies in China and discuss regional sustainable development and resources environment policies. We utilized the Exploratory Spatial Data Analysis (ESDA) method to analyze the characteristics of the spatio-temporal distribution of the total wastewater discharge among 31 provinces in China from 2002 to 2013. Then, we discussed about the driving factors, affected the wastewater discharge through the Logarithmic Mean Divisia Index (LMDI) method and classified those driving factors. Results indicate that: (1) the total wastewater discharge steadily increased, based on the social economic development, with an average growth rate of 5.3% per year; the domestic wastewater discharge is the main source of total wastewater discharge, and the amount of domestic wastewater discharge is larger than the industrial wastewater discharge. There are many spatial differences of wastewater discharge among provinces via the ESDA method. For example, provinces with high wastewater discharge are mainly the developed coastal provinces such as Jiangsu Province and Guangdong Province. Provinces and their surrounding areas with low wastewater discharge are mainly the undeveloped ones in Northwest China; (2) The dominant factors affecting wastewater discharge are the economy and technological advance; The secondary one is the efficiency of resource utilization, which brings about the unstable effect; population plays a less important role in wastewater discharge. The dominant driving factors affecting wastewater discharge among 31 provinces are divided into three types, including two-factor dominant type, three-factor leading type and four-factor antagonistic type. In addition, the proposals aimed at reducing the wastewater discharge are provided on the basis of these three types.