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- Pretreated Agro-Industrial Effluents as a Source of Nutrients for Tomatoes Grown in a Dual Function Hydroponic System: Tomato Quality AssessmentPublication . Afonso, Alexandra; Ribeiro, Carlos; Carvalho, Maria João; Correia, Tânia; Correia, Pedro; Regato, Mariana; Costa, Idália; Fernandes, Annabel; Almeida, Adelaide; Lopes, Ana; Carvalho, FátimaIn a zero-waste approach for the agro-industrial sector, this study aimed to evaluate the reuse of cheese whey wastewater (chemical oxygen demand = 2.1 g L−1) pretreated by immediate one-step lime precipitation followed by natural carbonation as a nutritive solution for tomato production in hydroponic systems. Pretreated effluent, diluted with groundwater (1:6) and supplemented with nutrients, was utilized to irrigate different hydroponic systems designed to assess the influence of tomato rooting type (free/confined−setup_A) and the feed’s solution level (with/without water deep−setup_B). Plants and fruit development, fruit physicochemical characteristics and sensory analysis, and effluent quality after reuse were analyzed. Good quality tomato production with high crop yield was obtained. The highest marketable tomato weight per plant (682 g) was observed in setup_B with a deep-bed system, but setup_A, with free or confined rooting, presented similar values. The type of rooting, within setup_A or water deep within setup_B, did not significantly influence plant and fruit characteristics. The highest maturity and flavor indexes were observed for setup_A with free rooting. Regarding sensory analysis, setup_A often scored the highest in terms of overall appreciation with free or confined rooting. The reuse of cheese whey wastewater in hydroponics reduced freshwater consumption for crop production, allowed for a treated final effluent and prevented soil degradation in a sustainable circular economy methodology.
- Hydroponic System: A Promising Biotechnology for Food Production and Wastewater TreatmentPublication . Prazeres, Ana R.; Albuquerque, António; Luz, Silvana; Jerónimo, Eliana; Carvalho, FátimaSeveral 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.
- Reuse of Pretreated Agro-Industrial Wastewaters for Hydroponic Production of LettucePublication . Afonso, Alexandra; Regato, Mariana; Patanita, Mariana; Luz, Silvana; Carvalho, Maria João; Fernandes, Annabel; Lopes, Ana; Almeida, Adelaide; Costa, Idália; Carvalho, FátimaThe utilization of agro-industrial wastewaters (AIWWs), pretreated by immediate one-step lime precipitation + natural carbonation, as a nutritive solution for the hydroponic production of lettuce was evaluated. The AIWWs studied were olive mill wastewater (OMW), winery wastewater (WW), and cheese whey wastewater (CWW). Lettuces (Lactuca sativa L. var. crispa) were grown in a closed nutrient film technique hydroponic system, using the pretreated AIWWs (OMW-T, WW-T, and CWW-T) and a control nutrient solution (CNS). The growth and sensory analysis of lettuces and the environmental parameters of effluents after hydroponics were evaluated. The average number of lettuce leaves obtained with nutrient solutions prepared with AIWW-T was lower than that from CNS, but the highest lettuce chlorophyll content was attained with CWW-T, which also presented the best grow results. In general, sensory analysis did not show significant differences from the lettuces grown in the different pretreated AIWWs and CNS. As for the environmental parameters of the effluents from hydroponics, according to the Portuguese legislation, only the chemical oxygen demand of the OMW-T and WW-T presented slightly higher values than that of the environmental limit values for discharge in surface waters, showing the feasibility of using pretreated agro-industrial effluents in hydroponic lettuce cultivation, while obtaining a treated effluent, in a circular economy perspective.