Sustainable Treatment of Aquaculture Effluents – What Can We Learn from the Past for the Future?

Many aquaculture systems generate high amounts of wastewater containing compounds such as suspended solids, total nitrogen and total phosphorus. Today, aquaculture is imperative because fish demand is increasing. However, the load of waste is directly proportional to the fish production. Therefore, it is necessary to develop more intensive fish culture with efficient systems for wastewater treatment. A number of physical, chemical and biological methods used in conventional wastewater treatment have been applied in aquaculture systems. Constructed wetlands technology is becoming more and more important in recirculating aquaculture systems (RAS) because wetlands have proven to be well-established and a cost-effective method for treating wastewater. This review gives an overview about possibilities to avoid the pollution of water resources; it focuses initially on the use of systems combining aquaculture and plants with a historical review of aquaculture and the treatment of its effluents. It discusses the present state, taking into account the load of pollutants in wastewater such as nitrates and phosphates, and finishes with recommendations to prevent or at least reduce the pollution of water resources in the future.DAA

Potassium, an important element to improve water use efficiency and growth parameters in quinoa (Chenopodium quinoa) under saline conditions

Due to changes in the ecosystem and misuse of resources, salinity also increases. Approximately 20% of all irrigated land is affected by salinity and this will increase over time. Therefore, it is necessary to develop more environmentally friendly agricultural techniques but also to exploit potential crops with high nutritional value and tolerance to salinity like quinoa (Chenopodium quinoa Willd.). In this context, potassium is an essential macronutrient for plant growth and development. Furthermore, one of the strategies of some salt-tolerant plants is to increase the uptake of potassium under saline conditions such that the K+/Na+ ratio is maintained for a proper osmotic regulation in cells. Therefore, a study was conducted to investigate the effect of different concentrations of potassium (0.5, 2 and 6 mM K) on quinoa under different salinities (0, 100 and 200 mM NaCl). According to the results, an adequate supply of potassium under moderate salinity conditions benefited the plant growth, with a higher potassium uptake in the presence of salt. Under saline conditions, plant transpiration decreased significantly with a high correlation with stomatal density and a greater water use efficiency. Therefore, under saline conditions, adequate doses of potassium are highly recommended in quinoa cultivation. © 2021 The Authors. Journal of Agronomy and Crop Science published by Wiley-VCH GmbH

Halophyte plants and their residues as feedstock for biogas production—chances and challenges

The importance of green technologies is steadily growing. Salt-tolerant plants have been proposed as energy crops for cultivation on saline lands. Halophytes such as Salicornia europaea, Tripolium pannonicum, Crithmum maritimum and Chenopodium quinoa, among many other species, can be cultivated in saline lands, in coastal areas or for treating saline wastewater, and the biomass might be used for biogas production as an integrated process of biorefining. However, halophytes have different salt tolerance mechanisms, including compartmentalization of salt in the vacuole, leading to an increase of sodium in the plant tissues. The sodium content of halophytes may have an adverse effect on the anaerobic digestion process, which needs adjustments to achieve stable and efficient conversion of the halophytes into biogas. This review gives an overview of the specificities of halophytes that needs to be accounted for using their biomass as feedstocks for biogas plants in order to expand renewable energy production. First, the different physiological mechanisms of hal-ophytes to grow under saline conditions are described, which lead to the characteristic composition of the halophyte biomass, which may influence the biogas production. Next, possible mechanisms to avoid negative effects on the anaerobic digestion process are described, with an overview of full-scale applications. Taking all these aspects into account, halophyte plants have a great potential for biogas and methane production with yields similar to those produced by other energy crops and the simultaneous benefit of utilization of saline soils

Screening of emerging pollutants (Eps) in estuarine water and phytoremediation capacity of tripolium pannonicum under controlled conditions

The increasing number of pharmaceuticals in the environment and their difficult biodegra-dation, can lead to bioaccumulation in different trophic compartments. Their bioaccumulation can have negative consequences, especially in the generation of bacterial resistance by antibiotics, but also in the impairment of plant and animal metabolism. The Tejo estuary in Portugal is the habitat for many plant and animal species, which are also prone to this type of contamination. There-fore, in the present study different classes of emerging pollutants (EPs) were surveyed in water samples in the Tejo estuary, including antibiotics, anticonvulsants, antidepressants, lipid-lowering drugs, anti-inflammatory drugs, beta-blockers and analgesics. According to the results, only four compounds were detected in water samples collected at the three selected salt marshes, including carbamazepine, fluoxetine hydrochloride, venlafaxine hydrochloride and acetaminophen. Having the detected substances as a basis, a subsequent study was performed aiming to investigate the uptake and biodegradation capacity of halophytes, using Tripolium pannonicum as a model plant culti-vated under controlled conditions with different concentrations of the found EPs. This experimental approach showed that T. pannonicum was able to uptake and degrade xenobiotics. Moreover, the application of sulfamethazine, as a model antibiotic, showed also that this species can uptake and degrade this compound, although the degradation rate and process proved to be compound-specific. This was also confirmed using crude plant extracts spiked with the different EPs. Thus this species is a potential candidate for the remediation of marine water and sediments contaminated with environmentally-significant EPs. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Halophytes as Feedstock for Biogas Production: Composition Analysis and Biomethane Potential of Salicornia spp. Plant Material from Hydroponic and Seawater Irrigation Systems

The halophyte plant species Salicornia europaea and Salicornia ramosissima were investigated for their potential to serve as a substrate for biogas production. Salicornia europaea was cultivated in hydroponic systems under varying salt concentrations (0, 10, 20, and 30 g/L NaCl), while S. ramosissima was grown in greenhouse farming with aquaculture effluent irrigation. The biomethane potential of the two halophyte feedstocks was determined through batch experiments, and correlations to the plant biochemical composition were investigated. Ash and mineral content of S. europaea was correlated to the increasing salt concentration used for plant cultivation in hydroponic systems. No indication of inhibition of the anaerobic digestion process was detected for sodium concentrations of up to 2400 mg/L in the anaerobic batch-test assays. The highest biomethane yield of S. europaea of 250 mL CH4/gVS was obtained when grown under 20 g/L NaCl and up to 300 mL CH4/gVS for S. ramosissima. By concentrating the dry matter content, the biomethane yield per ton of feedstock could be increased from 24 m3 CH4/t of the fresh halophyte plant to 74 m3 CH4/t by fractionation into a pulp fraction and to 149 m3 CH4/t by drying of the plant at room temperature for 1 week. © 2022 by the authors. Licensee MDPI, Basel, Switzerland

NASA Human Exploration Rover Challenge

NASA\u27s Human Exploration Rover Challenge, held annually in at the Marshall Space Flight Center in Huntsville, Alabama, is an engineering design challenge that asks teams of student engineers to design a human-powered vehicle capable of traversing a simulated lunar surface. The rover must be able to be transported in a 5x5x5 foot cube, echoing the design constraint faced by the engineers who built the Lunar Roving Vehicles used by the astronauts of the later Apollo missions

Exposure of Common Bean Seeds to Liquid Nitrogen Modifies Mineral Composition of Young Plantlet Leaves

Many publications describe cryopreservation techniques but only a few studies have focused on the biochemical and physiological changes occurring in plants regenerated from seeds exposed to liquid nitrogen. This paper aims at describing the effect of common bean seed cryostorage on mineral nutrition of young plantlets. The following elements were measured on leaves of 10-day-old plantlets from non-cryopreserved and cryopreserved seeds: Al, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, S, Se, Sr and Zn. At 10 days after sowing, both treatments (control and cryopreserved seeds) showed 100% seed germination without any visual phenotypic difference. However, contents of several elements in the leaves were different. Exposure of seeds to liquid nitrogen decreased Cu, Cd and Na uptake and increased absorption of B and Al. Further studies are required to understand the mechanisms underlying the relationship between seed exposure to liquid nitrogen and mineral nutrition during the early stages of plantlet growth.DAADLeibniz University of HannoverUniversity of Ciego de Avila, Cub

Physico-chemical characterization of walnut shell biochar from uncontrolled pyrolysis in a garden oven and surface modification by ex-situ chemical magnetization

The shells of walnuts (WS) are major refuse in the global fruits and nuts trade. This, otherwise discarded, lignin-rich material can be carbonized to biochar—a value-added product with environmental applications such as carbon sequestration, soil amelioration, and pollutant adsorption. These applications are dictated by structural and chemical characteristics of the biochar carbon. Conventional controlled pyrolysis (CPy) of biomass is cost-intensive and technically too complex for widespread adoption, especially in emerging economies. Here, walnut shell biochar (BWS0) is derived through uncontrolled pyrolysis (UCPy) in a pyrolysis oven and further hybridized as magnetic biochar through ex-situ chemical co-precipitation. The physico-chemical characteristics of biochar and its water-extractable fractions are comprehensively investigated to understand their carbon structure and environmental applicability. The sp2 amorphous carbon sequestered in BWS0 is 0.84 kgCO2/kgbiomass with a BET (N2) surface area of 292 m2/g and is comparable to biochar from CPy in terms of carbon structure. The polyaromatic hydrocarbons present are only trace amounts of naphthalene, biphenyl, and phenanthrene. The magnetization decreases porosity of BWS0 while greatly facilitating its separation from aqueous media. BWS0 is suitable for adsorption of cations (between pH 2.8 and 9.45) and hydrophobic pollutants with only 19 mg L−1 fouling from their intrinsic dissolved organic carbon. In combination with fast-release N, P fertilizers, BWS0 (C/N of 24.8) is suitable for application in hydrophilic soils at higher loading rates. The results suggest an avenue where WS biochar can also be prepared via UCPy for direct environmental applications. Future investigations into soil incubation and adsorption tests are recommended. Graphical abstract: [Figure not available: see fulltext.

The levels of sulfur-containing metabolites in Brassica napus are not influenced by the circadian clock but diurnally

Adapting biological processes to an endogenous rhythm enables plants to cope with the daily changes in light and temperature in a more predictable way enhancing growth and fitness. A number of biological processes such as metabolic pathways as well as the immunity in plants are under diurnal or circadian control. In this study a possible circadian regulation of key enzymes in the sulfur assimilation and the corresponding metabolites was investigated in the agriculturally important crop plant oilseed rape (Brassica napus). Leaves of a commercially available cultivar were harvested in the course of a day under diurnal and under free-running conditions with constant light. Analyses in this study were focused on sulfur-containing metabolites and expression analysis of enzymes involved in sulfur assimilation. Expression analysis showed that the transcript levels of the sulfate transporters Sultr3;1 and Sultr4;2 as well as APR2 and APR3 oscillated diurnally. Results revealed a periodic rhythm of sulfur-containing metabolites such as glutathione, sulfate and certain glucosinolates in the course of a day which were only partly maintained under constant light. Therefore, we conclude that a diurnal rhythm and not the circadian clock regulates sulfur metabolism in plants

Autophagic Flux Modulation by Wnt/β-Catenin Pathway Inhibition in Hepatocellular Carcinoma

Autophagy targets cellular components for lysosomal-dependent degradation in which the products of degradation may be recycled for protein synthesis and utilized for energy production. Autophagy also plays a critical role in cell homeostasis and the regulation of many physiological and pathological processes and prompts this investigation of new agents to effect abnormal autophagy in hepatocellular carcinoma (HCC). 2,5-Dichloro-N-(2-methyl-4-nitrophenyl) benzenesulfonamide (FH535) is a synthetic inhibitor of the Wnt/β-catenin pathway that exhibits anti-proliferative and anti-angiogenic effects on different types of cancer cells. The combination of FH535 with sorafenib promotes a synergistic inhibition of HCC and liver cancer stem cell proliferation, mediated in part by the simultaneous disruption of mitochondrial respiration and glycolysis. We demonstrated that FH535 decreased HCC tumor progression in a mouse xenograft model. For the first time, we showed the inhibitory effect of an FH535 derivative, FH535-N, alone and in combination with sorafenib on HCC cell proliferation. Our study revealed the contributing effect of Wnt/β-catenin pathway inhibition by FH535 and its derivative (FH535-N) through disruption of the autophagic flux in HCC cells