Hydroponic System: A Promising Biotechnology for Food Production and Wastewater Treatment

Several regions of the world are suffering from water scarcity and available water pollution. Mediterranean countries (such as Portugal, Spain, Italy, Greece, Tunisia, Israel, and Jordan) do not meet the requirements in terms of quantity that have been increasing in the last decades for the various sectors, due to lack of water resources, winters with low rainfalls, and summers with hot and dry conditions. Agriculture is the leading water-consuming sector (70%–80%), followed by industry and domestic use. However, industrial and domestic uses are considered priorities, conditioning the amount of accessible water for the agriculture sector. the use of reclaimed water should be considered in the integrated water management system to avoid damages to the environment (surface and underground water, soil, fauna, and flora) and public health. The use of wastewater for irrigation should be carefully investigated and planned in terms of proper treatment, treated wastewater quality, volume of treated wastewater used, application method, physicochemical characterization of soil, nutritional needs of plants, distance to existing water sources, risk of animal and human contamination, and others. Environmental and economic gains can be achieved by reusing wastewater if the study, planning, and application are performed in a sustainable basis.info:eu-repo/semantics/publishedVersio

Evaluation of herbaceous crops irrigated with treated wastewater for ethanol production

The competition for freshwater between agricultural, industrial, and civil uses has greatly increased in Mediterranean basin characterized by prolonged dry seasons. The aim of this study was to evaluate biomass production and the potential ethanol production of promising “no-food” herbaceous crops irrigated with low quality water at different ETc restitutions (0%, 50 and 100%). The research was carried out, in 2011 and 2012, in an open field near the full-scale constructed wetland (CW) municipal treatment plant located in the Eastern Sicily (Italy). The CW effluent has been applied in a experimental irrigation field of Vetiveria zizanoides (L.) Nash, Miscanthus x giganteus Greef et Deu. and Arundo donax (L.). Physical, chemical and microbiological analyses were carried out on wastewater samples collected at inlet and outlet of CW and pollutant removal efficiencies were calculated for each parameter. Bio-agronomical analysis on herbaceous species were made with the goal to evaluate the main parameters such as the plant dimension, the growth response and the biomass production. Biomass dry samples were processed with a three-step chemical pretreatment, hydrolysed with a mix of commercial enzymes and next fermented to obtain the yield of ethanol production. Average TSS, COD and TN removal for CW were about 74%, 67% and 68%, respectively. Although the satisfactory Escherichia coli removal, about 3.5 log unit for both beds on average, CW didn’t achieve the restrictive Italian law limits for wastewater reuse. As expected, irrigation was beneficial and the full ET replenishment increase the biomass productivity as compared to the other two treatment. The mean productivity of Vetiveria zizanoides and Myscanthus x giganteus were about 9, 26 and 38 t ha–1 and 3, 7 and 12 t ha–1 respectively in 0%, 50% and 100% ETc restitutions. Arundo donax gave higher values of dry biomass (78 t ha–1 in 100% ETc restitution in 2011 season), and potential ethanol production (about 3,744 kg ha–1). These results suggest the interest in the use of constructed wetland effluents for the irrigation of energy crops to obtain second generation ethanol, particularly in semiarid regions such as the Mediterranean area

Sustainable Biodiesel Production from Microalgae Cultivated with Piggery Wastewater

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Practice of wastewater irrigation and its impacts on human health and environment: a state of the art

The practice of wastewater irrigation lessens the pressure on the aquatic environment by minimizing the use of freshwater resources. However, this may lead to significant damage to the human health and environments. Recycled wastewater possesses a substantial amount of nutrients that act as fertilizers for crops and facilitate the metabolic action of microorganisms. The major advantages of wastewater irrigation are increased agricultural production, nutrient recycling, reduced stress on freshwater, economical support and provision of livelihoods for farmers. However, several harmful impacts of wastewater irrigation are also prominent due to inappropriate wastewater management and irrigation practices. These include severe hazards to farmer’s health, contamination of agricultural land and crops with toxic metals, chemical compounds, salts and microbial pathogens. In addition, long-term irrigation using wastewater can significantly affect the groundwater through leakage of salty and toxic metal-rich wastewater making it unfit for human consumption. Wastewater irrigation may also alter the physicochemical properties and microbiota of soil, which in turn can disturb land fertility and crop productivity. Several factors need to be considered while using treated or partially treated wastewater for irrigation such as diversity and type of pollutants, available nutrients, pathogenic microorganisms and soil salinity. In this review paper, we assess the impact of wastewater irrigation on humans as well as on the environment based on available case studies globally, outline current use of wastewater for irrigation of agricultural crops such as cereals, vegetables, fodder crops, including agroforestry and discuss suitable management practices of wastewater reuse for irrigation

Water reuse: dairy effluent treated by a hybrid anaerobic biofilm baffled reactor and its application in lettuce irrigation

There is a synergy between the large quantities of organics-rich effluents generated by the dairy industry and the continually increasing water needs for crop irrigation. In this sense, this study aimed at evaluating the effect of decreasing the hydraulic retention time (HRT) on the stability and efficiency of a hybrid anaerobic biofilm baffled reactor (HABBR) treating simulated fat- and salt-rich dairy wastewater, followed by its agricultural reuse. The reactor was monitored over 328 days, during which 72, 24, and 12 hours were the hydraulic detention times. After achieving steady-state, the reactor presented organic matter removal above 90% and produced biogas with 41 ± 23%, 53 ± 3%, and 64 ± 12% of methane for HRTs of 72, 24, and 12 hours, respectively. The best process performance was observed for an HRT of 24 h, and thus, a lettuce culture was irrigated with the treated effluent. The irrigation was performed in five different treatments, for which the amount of treated effluent added to tap water varied from 0 to 100%. Both the effluent and the harvested vegetables were evaluated for microbial contamination. Apart from the 75% effluent supply condition, there were no losses in leaf mass or area observed, and instead, there was an increase of these parameters for the 25 and 50% effluent supply treatment. The use of dairy effluent treated by the HABBR allowed for microbiologically safe food production. Therefore, the process offered both potential cost reduction for fertilizers, preservation of water resources, and a renewable energy source.The authors are grateful to Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – CAPES for the grants to L. K. A. Santos (Finace Code 001) and to M. M. S. Alves (PVE 123/2012, process no. 23038.009805/2012-39), as well for the financial support.info:eu-repo/semantics/publishedVersio

Microalgal systems for wastewater treatment: technological trends and challenges towards waste recovery

Wastewater (WW) treatment using microalgae has become a growing trend due the economic and environmental benefits of the process. As microalgae need CO2, nitrogen, and phosphorus to grow, they remove these potential pollutants from wastewaters, making them able to replace energetically expensive treatment steps in conventional WW treatment. Unlike traditional sludge, biomass can be used to produce biofuels, biofertilizers, high value chemicals, and even next-generation growth media for “organically” grown microalgal biomass targeting zero-waste policies and contributing to a more sustainable circular bioeconomy. The main challenge in this technology is the techno-economic feasibility of the system. Alternatives such as the isolation of novel strains, the use of native consortia, and the design of new bioreactors have been studied to overcome this and aid the scale-up of microalgal systems. This review focuses on the treatment of urban, industrial, and agricultural wastewaters by microalgae and their ability to not only remove, but also promote the reuse, of those pollutants. Opportunities and future prospects are discussed, including the upgrading of the produced biomass into valuable compounds, mainly biofuels.This research was funded by the Foundation for Science and Technology (FCT) through UIDB/04326/2020 and the GreenTreat (PTDC/BTA-BTA/31567/2017) and Red CYTED P319RT0025— RENUWAL—Red Iberoamericana para el Tratamiento de Efluentes con Microalgas projects and CRESC-Algarve and the European Regional Development Fund (ERDF) programs via the ALGAVALOR (ALG-01-0247-FEDER-035234) project.info:eu-repo/semantics/publishedVersio

Challenges of a feasible route towards sustainability in environmental protection

Anaerobic processes for treatment of low and high strength wastewaters and solid wastes constitute the core method in the natural biological mineralization (NBM) treatment concept. When adequately combined with the complementary NBM-systems and modern clean water saving practices in wastewater collection and transport, they represent a feasible route to sustainable environmental protection (EPsus), in essence even towards a more sustainable society. Despite the development and implementation of modern high rate Anaerobic Wastewater Treatment (AnWT-) systems and complementary innovative NBM-processes, the considerable progress made since the seventies in fundamental insights in microbiology, biochemistry and process technology, still numerous challenging improvements in the NBM-field can be realized. This contribution is mainly based on the insights attained from wide ranging literature evaluations and the results of experimental research conducted by numerous PhD students who participated in our group over the last four decades. An attempt is made here to identify major facets on which an improved insight can, and consequently should, be obtained in order to accomplish more optimal operation and design of various types of Anaerobic Degradation (AnDeg-) processes