The effect of the air blast sprayer speed on the chemical distribution in vineyard.

A study was conducted to determine the spray deposition patterns for air blast sprayers used to apply chemicals to the canopy of Semillon grapevine in vineyard. The application carried out in 12 bars and three sprayer speed (2.1-4.9-7.7 km h(-1)). The spray deposition was measured on the point in the different distances (1.5-3-6-9 m). Tartrazine were applied as tracer material. Maximum spray deposit was obtained 66.1 mg cm(-2) at sprayer speed of 2.1 km h(-1) and minimum deposit was obtained 37.1 mg cm(-2) at sprayer speed of 7.7 km h(-1). The results showed that the sprayer speeds had significant effect on spray deposit distribution and increasing of the sprayer speed increased drift.

Optimization of phosphorus precipitation from swine manure slurries to enhance recovery.

Laboratory experiments were conducted using magnesium chloride (MgCl2 x 6H2O, 64% solution) to force the precipitation of phosphorus and reduce the concentration of soluble phosphorus (PO4(3-)) in two swine wastes. One of the swine wastes tested contained a high concentration of PO4(3-) (initially approximately 1,000 mg/L), and the other swine waste tested contained a low concentration of PO4(3-) (initially approximately 230 mg/L). The precipitation reactions were performed to determine the required reaction time, pH, magnesium addition rate and seed material for future precipitate recovery work. For the high and low concentration waste, a 10-minute reaction time at a pH of 8.6 was sufficient to remove 98 and 96% of the PO4(3-) from solution. A molar ratio of Mg2+:PO4(3-) of 1.6:1 was determined to be effective for PO4(3-) removal from both the low and high strength wastes. At a molar ratio of 1.6:1, the PO3- in the high concentration waste was reduced from 590 to 12 mg/L. In the low concentration waste, the PO4(3-) concentration was reduced from 157 to 15 mg/L. Seeding the reaction did not significantly enhance the recovery process.

Recovery of ammonia as struvite from anaerobic digester effluents.

The effects of environmental conditions on ammonia removal as struvite (Magnesium ammonium phosphate, MAP) were studied in a laboratory scale batch reactor. MAP precipitation was carried out by adding phosphoric acid and magnesium source either as MgCl, or MgO. The effect of temperature, pH, MgN:P ratios were studied. Temperature did not significantly affect ammonia removal between 25-40 degrees C and over 90% removal was obtained. The effect of pH, however,was significant and highest removal was reached at pH 8.5-9.0. The various stoichiometric ratios of ammonium to Mg and P have been tested and slight excess of Mg and P found to be beneficial for higher recovery of ammonia as struvite. However further increase in Mg and P ratios did not result in further ammonia removal which is also costly for the practical application of the process. When MgO was used as M source,the ammonia recovery was 60-70% whereas the useMgCl2 has increased this figure up to 95%. In addition a two step purification process was developed to recover MAP crystals from impurities of the anaerobic digester. Firstly, precipitates were dissolved in acid and impurities were removed by centrifugation. The clarified supernatant was re-precipitated by adjusting its pH with caustic. It was shown that in the two steps process white MAP crystals could be obtained with over 85% recovery to be used for another applications. The economical analysis of the process has shown that ammonia in the digester effluents can be recovered at the cost of $7.5-8.0 kg(-1) NH4+-N. The rate of reaction is very fast and is completed almost in minutes. This simplifies the process design resulting in a smaller reaction vessel.