Desempenho de sistema de irrigação por gotejamento utilizado na aplicação de água residuária de suinocultura / Performance of dripping irrigation system using swine wastewater

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

The objective of this work was to analyze the performance of a drip irrigation system using swine wastewater. The following parameters were evaluated: (a) removal of suspended solids, oils and greases by passing the effluent through sloped static screens; (b) influence of service pressure on clogging of drippers operating with effluent and water; and (c) effect of proportion of water on clogging of drippers, after effluent application. The experiment was conducted at the Swine Wastewater Treatment and Trickle Application Unit (UTARS), in the Federal University of Viçosa (UFV), Viçosa, MG. In the first stage of this work, an experimental bench consisting of five screens of 47, 56, 77, 106 and 154 m mesh sizes was set up to filter swine effluent. Wastewater sampling was carried out hourly upstream and downstream of the sieves, during a 4-hour period. For the second and third stages of the work, another experimental bench was set up, consisting of two control units, for effluent and water pumping; a brick platform; and four fertirrigation units, with three types of drippers: G1 - non-compensating with nominal flow of 2 L h-1; G2 - non-compensating with nominal flow of 1.7 L h-1; and G3 - self compensating with nominal flow of 3.6 L h-1. Each fertirrigation unit consisted of three subunits, one for each type of dripper. Three lateral lines of 18 m length were installed per subunit. Twenty-two emitters for flow measurement were identified in all lateral lines. Physical, chemical and biological analyses of the effluent and water that supplied the fertirrigation units were performed during the trials. In the second stage of the work, the four fertirrigation units operated daily at pressures 75, 145, 215 and 285 kPa for four hours, with effluent applied during the first two hours and water in the remaining time. Evaluation of water application uniformity in the subunits of fertirrigation was carried out every 20 h, during the period of effluent application. In the third stage of the work, the four fertirrigation units operated at the pressure of 105 kPa, while the levels were: level 1E3A - one hour of effluent application followed by three hours of water application; level 2E2A - two hours of effluent application followed by two hours of water application; level 3E1A - three hours of effluent application followed by one hour of water application; and level 4E - four hours of effluent application. Evaluation of water application uniformity in the subunits of fertirrigation was carried out every 20 h, during the period of effluent application. The results showed that large removals of suspended solids, oils and greases were only obtained with the 47-m screen. The biofilm formation resulted from the interaction among the physical, chemical and biological agents caused partial and total dripper clogging, and consequently reduction in the uniformity of effluent application in the fertirrigation subunits. The G1 dripper was more susceptible to clogging than G2 and G3, because of the lowest effluent flow speed and longest labyrinth length. The increase in service pressure decreased clogging level only in the fertirrigation subunits with the dripper G1 with the increase in the effluent flow speed inside the emitter. On average, the subunits operating at service pressures P1 and P2 showed higher clogging levels compared with those at service pressures P3 and P4. The levels 1E3A and 4E were most effective in reducing dripper clogging in the fertirrigation subunits, while highest clogging levels occurred at 2E2A and 3E1A. The combinations providing lowest clogging were dripper G3 associated with levels 1E3A and 4E. In the field, the clogging levels of drippers G1, G2 and G3 could be lower, because of the shortest time of equipment operation for a sustainable application of swine wastewater.

ASSUNTO(S)

engenharia agricola gotejadores irrigação por gotejamento wastewater drip irrigation Água residuária obstrução prevention drippers medidas preventivas obstruction

ACESSO AO ARTIGO

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