Sistema de Wetland construído com macrófita nativa echinodorus subalatus para tratamento de águas cinzas

Abstract

Considering the difficulty for rural populations and low population density, particularly those in the semi-arid region, to be contemplated with the collection and treatment of domestic sewage, it becomes important to search for simplified, economical and decentralized technologies, such as constructed wetlands, in order to ensure better quality of life, public health and minimization of environmental damage. Thus, in the present work, the efficiency of the subsurface vertical descending wetland system was investigated in the treatment of gray wastewater, using the species Echinodorus subalatus, an emergent macrophyte native to Ceará, which is directly or indirectly related to the occurrence of mechanisms for removing pollutants associated with these systems. The use of species native to the northeastern semiarid region aims to prevent the entry of exogenous species commonly used in these systems and that may pose risks to the local fauna and flora. In addition, these species have fast growth because they are associated with seasonality, having few months to complete their cycle. The low species richness used in wetland systems is a good argument for the study of new species native to seasonal environments found in the semi-arid region of Brazil. As a substrate, unconventional materials such as ceramic brick and sea shells were used, both discarded materials from civil construction and shellfish activity, respectively, in order to remove a useful destination for these waste. To analyze the composition and the biofilm adhered to them, photographs obtained from scanning electron microscopy and Energy Dispersive Spectroscopy were taken. In order to monitor the effluent, input and output analyzes will be carried out: pH, temperature, chemical oxygen demand, nitrate, nitrite, ammonia, phosphorus, anionic surfactant, hardness, alkalinity, electrical conductivity and dissolved oxygen. The bacterial community present in the effluent was quantified by molecular biology techniques from the extraction and sequencing of the DNA present in the sample. For the population residing in the semi-arid region of northeastern Brazil, the reuse of water in agriculture is a possible solution to alleviate the problem of water scarcity and comply with the concept of sustainability, so that the use of treated effluent in irrigation is foreseen of cowpea, when in addition to the monitoring variables mentioned, the concentration of E. coli present at the entrance and exit of the system and the growth variables (stem height, number of leaves and stem diameter) and production (amount of and size of pods and grains). As references for the quality of the final effluent, the standards established by Resolution COEMA No. 2, of February 2, 2017, which provides for standards and conditions for the release of liquid effluents generated by polluting sources and by the United States Environmental Protection Agency (EPA ). A completely casual design was used in a factorial scheme with 6 treatments (1 bean crop, 6 effluents), with 4 replications (pots) and each pot with 2 plants. In this way, the thesis was divided and structured in 5 sections: 1) General introduction with hypotheses and justifications of the study on the treatment of wastewater in wetland systems using native macrophyte and unconventional substrates, 2) a reviewarticle entitled “Constituents of the constructed wetlands with vertical subsurface flow for wastewater treatment: a review”, which addresses the main constituents of wetlands constructed with vertical subsurface flow, as well as the state of the art of this technology, based on a bibliographical survey based on exclusion criteria and inclusion using the keywords: vertical flow, constructed wetland, treatment, macrophytes and substrate, 3) Experimental article, entitled “Use of seashells in constructed wetland for the removal of anionic surfactant in wastewater”, in which the viability of the use of marine shells as substrate of the system for the removal of pollutants, 4) Experimental article , titled “Production of cowpea (vigna unguiculata .walp) in a semi-arid area using constructed wetland effluent as irrigation water” in which the feasibility of using waste water from the treatment system for irrigation of cowpea was evaluated, 5 ) General conclusions about the thesis.