Reuse of stabilized sludge and treated wastewater
The sludge mixture from the anaerobic digesters and aeration tank during phase 3 was collected and analyzed in terms of chemical composition for potential use for gricultural production systems. As shown in Table 7, the characteristics are very similar to that reported by Kuroshima (1994). Both of these two studies used the same source of pig waste. These nutrient and mineral elements are essential to the plant growth. The sludge collected from this study for the chemical analysis is from both the
anaerobic digestion of concentrated pig waste and aerobic treatment of diluted pig wastewater. The sludge collected from the other study (Kuroshima,1994) was only from the anaerobic digestion of highly concentrated pig wastes. Based on the contents of nitrogen and phosphorus, the stabilized sludge generated from this study is very similar to other study (Kuroshima, 1994). The effluent from the polishing tank of the swine wastewater treatment system has been used for irrigation of the pasture during the period of the experiment. The effluent quality listed in Table 8 was applied during the three periods of this study. Based on the application rate of 1000 gallons.
(3.785 m3) per day and 2 acres (8094 m*) of pasture practiced in these three phases of study, the nitrogen application rate is under the suggested application rate for forage crops (Loehr, 1984). More importantly,no complaints of odor were received during
the application. According to the ‘Guidelines for the Treatment and Use of Reclaimed Water in the State