The canonical correlation is used to correlate groups of distinct variables. The objective of this study was to use canonical correlation analysis to evaluate the interaction between water quality attributes clogging-causing and the hydraulic performance of non-pressure compensating drippers operating with dilutions of aquaculture effluent in well water. The experiment was in a completely randomized design in a split-split-plot scheme with three replicates, with five dilutions in the plots (Dilution 1: 100% aquaculture effluent; Dilution 2: 75% aquaculture effluent + 25% well water; Dilution 3: 50% aquaculture effluent + 50% well water; Dilution 4: 25% aquaculture effluent + 75% well water; and Dilution 5: 100% well water), three emitters in the sub-plots (ST (1.6 L h^-1), SL (1.6 L h^-1) and NJ (1.7 L h^-1)), and three operating times in the sub-subplots (0, 80 and 160 hours, in which 0 hours operating time means the start of evaluations). The statistical analyses performed were correlation matrix and canonical analysis. The canonical correlation analysis indicated that when the concentrations of attributes increase, the hydraulic performance of the drippers decreases. The interaction of this group of attributes indicates that the clogging of drippers operating with the five dilutions of aquaculture effluent in well water occurs by the combined action of physical, chemical, and biological agents. The ST dripper was the least sensitive to the group of quality attributes of the dilutions, whereas the most sensitive was the SL dripper.

VAZÃO DE GOTEJADORES APLICANDO ÁGUA RESIDUÁRIA DA CASTANHA DE CAJU

Water scarcity in Brazil’s semi-arid region necessitates the agricultural reuse of aquaculture effluents, although emitter clogging remains a challenge. This study evaluated clogging mitigation in drip irrigation systems using liquid anti-clogging fertilizer. The experiment employed a split–split–plot scheme with three water treatments (supply water, aquaculture effluent, and effluent with liquid fertilizer) and three emitter types (ST, SL, and GA), assessing performance over 360 h. A water quality analysis at 0, 160, and 360 h complemented hydraulic evaluations of the average flow rate variation and Christiansen uniformity coefficient measured every 40 h. Energy-dispersive X-ray spectroscopy, X-ray diffractometry, and scanning electron microscopy were used to characterize biofouling. The results showed that the liquid fertilizer mitigated the clogging by biofouling in the three types of emitters, but only the ST emitter presented acceptable hydraulic performance rates. There are relationships between the anti-clogging effect of the liquid fertilizer, the structural characteristics of the emitters, and the flow velocity inside the labyrinths. The SL dripper applying only aquaculture effluent presented the highest clogging rate due to biofouling. Agricultural reuse is a strategy for the rational use of water resources that is of great relevance for arid and semi-arid regions and can insert aquaculture into the circular economy.

Water scarcity and the search for alternative water reuse are challenges faced in the Brazilian semi-arid region. The objective of this study was to predict the risk of clogging of drippers based on water quality attributes and to analyze the effects of industrial residual water and supply water on their hydraulic performance. Two experimental benches were set up in a completely randomized design, in split-split plots, with three replicates. Plots contained the types of water (supply water and reverse osmosis reject), subplots contained the types of non-pressure-compensating drippers (NST - 1.6 L h^-1, NSL - 1.6 L h^-1 and NDT - 1.7 L h^-1) and sub-subplots contained the evaluation times of the distribution uniformity coefficient and relative flow rate (0, 20, 40, 60, 80, 100, 120, 140 and 160 hours). At times 0, 80 and 160 hours, the attributes pH, electrical conductivity, total suspended solids, total dissolved solids, calcium, magnesium, iron and manganese were characterized in both types of water. The data were subjected to descriptive analysis, ANOVA and Tukey test at 5% probability level. In residual water, the attributes that represented a risk of clogging for drippers were pH, electrical conductivity, magnesium and total dissolved solids, while in supply water only pH represented risk. The interaction between types of water and operating time significantly affected both hydraulic performance indicators, but there was no significant effect of the dripper type factor.

O Brasil desponta como um dos países com maior potencial de produção aquícola, especialmente pela sua disponibilidade hídrica, clima favorável e ocorrência natural de espécies aquáticas. Entretanto, em um mundo que se preocupa cada vez mais com os problemas ambientais, investir no desenvolvimento sustentável desta atividade é essencial. Uma das melhores alternativas para reduzir os impactos ambientais da aquicultura é o reúso dos seus efluentes na agricultura, devido as suas diversas vantagens ambientais e econômicas. Do ponto de vista ambiental, o reúso agrícola é mais seguro quando realizado pela irrigação por gotejamento. As vantagens inerentes a este sistema são a elevada eficiência de aplicação, o baixo risco de contaminação do produto agrícola e de operadores no campo, a minimização dos riscos de escoamento superficial, percolação e acumulação de sais próximo ao sistema radicular e a prevenção de aerossóis. A principal limitação da irrigação por gotejamento é o entupimento de gotejadores que pode ser agravado pela qualidade da água de irrigação. Para minimizar este problema é necessário conhecer os aspectos técnicos dos emissores, os tipos de entupimento e seus fatores de influência, pela utilização das mais diversas técnicas de detecção da obstrução. Com o conhecimento adquirido dos aspectos que favorecem a obstrução dos gotejadores podem ser elaboradas ou escolhidas técnicas de minimização do entupimento que tornarão o reúso agrícola de efluentes, como o da aquicultura, mais eficiente e sustentável. PALAVRAS-CHAVE: obstrução; gotejadores; hidráulica; reúso agrícola.