Uso do subproduto da indústria cerâmica em colunas de filtragem para o tratamento de águas residuárias da cafeicultura

Abstract

All kinds of anthropogenic activities can cause negative environmental impacts. Therefore, studies and alternatives are necessary to mitigate these impacts, so that the activities can be developed with sustainability. Coffee cultivation is very important in the Brazilian economy and the external coffee market is quite demanding in quality, characteristic related to the type of post-harvest processing. The wastewater resulting from the post-harvest processes are called coffee wastewater that is obtained after harvest processing of coffee fruits (ARC). This wastewater contains a high concentration of organic and inorganic compounds. If ARC is disposed indiscriminately in soil or in water bodies, it can cause damage to the environment. Thus, they need a pretreatment to reduce their organic and inorganic load, in order to make their application in the soil more viable and with a lower phytotoxicity risk to the plants. An alternative for the ARC treatment is its filtering in filled columns of materials that have adsorbent capacity, such as ceramic industry by-product (SIC). This material consists of shards of roof tiles and bricks from parts that do not meet the standard for marketing or that suffered damage during the production process. The possibility of using SIC as a filter in the columns derives from its adsorption capacity and its stability, related to its mineralogical composition modified by the thermal treatment. Therefore, the objective of this study is to evaluate the use of SIC for the treatment of ARC, aiming to reuse it in coffee plantations. This study was carried out at the Federal University of Uberlândia and consisted of two steps: one aimed to evaluate the sorption and desorption capacity of phosphorus (P) and potassium (K) by SIC and another one aimed to evaluate the ARC treatment capacity in filtration columns. In the evaluation of P and K sorption and desorption behavior, the SIC was compared to the raw material used in the manufacture of roof tiles and bricks (MP) and with an Oxisol or “Latossolo Vermelho” (LV). The purpose of this evaluation was to elucidate the capacity of retention and release of these nutrients by SIC, making it possible to predict their behavior when used as an adsorbent in columns for the ARC treatment. According to the results, the SIC, compared to MP and LV, presented a higher capacity to adsorb P and higher capacity to desorb K. This behavior does not impede the use of SIC in the filtration columns, since the desorbed K can contribute to the reuse of the ARC in the coffee crop fertilization, by means of fertirrigation, replacing in part the conventional fertilizers. In the evaluation of ARC treatment in filtration columns, it was verified that SIC was efficient in reducing the pollutant potential of ARC by reducing turbidity, apparent color, Chemical and Biochemical Oxygen Demand and total phosphorus, as well as particulates not suitable for soil application. However, the filter allows the passage of dissolved particles, these being probably potassium ions. SIC provides a physical retention of particles. These changes in the ARCs resulting from the treatments are promising and potentiate their reutilization to fertilization of the coffee crop.