This study was conducted to know physical properties of animal waste by measuring distribution of particle diameter and sedimentation rate in slurry. The experiment was carried out on pig slurry and other cattle slurry. Distribution of particle diameter was measured by combining sieve analysis and microscopy. Distribution of sedimentation rate was measured by Andreasen pipette method and centrifugal sedimentation method. Experimental results from two methods were shown together.
Particle density of animal waste was estimated by the authors.
The results obtained from these experiments are summarized as follows.
1) Distribution of sedimentation rate for animal waste was measured by combining Andreasen pipette method and centrifugal sedimentation method. Distribution of particle diameter was measured by means of sieve analysis and microscopy. These methods were relatively simple and accurate and applicable over broad range.
2) It converted sedimentation rate in centrifugall force field into sedimentation rate Umg ((4) equation) in gravity field. Distribution of sedimentation rate and particle diameter obtained from different methods was expressed uniformly all over the measurement range.
3) The rate (1-K) of observed dissolution in animal waste was obtained from the asymptotic value K of distribution curve of residue on sedimenvation rate. It was about 10% for pig slurry and about 13% for cattle slurry.
4) Distribution of sedimentation rate for animal waste was found that the distribution curve for residue showed two step downward curve as shown in Fig. 4 and Fig. 5 and the distribution ranges were similar. Mean sedimentation rate was 0.1370cm/sec. for pig slurry and 0.0924cm/sec for cattle slurry.
5) As shown in Fig. 6 and Fig. 7, the distribution of particle diameter of animal waste showed that the distribution curve of residue was two step downward curve and touched the horizontal axis at R=0. Concentration to the small particle diameter for cattle slurry was more remarkable than for pig slurry. Mean particle diameter was 665μ for pig slurry and 458μ for cattle slurry.
6) By applying Rosin-Rammler distribution function with K as asymptotic value to distribution of sedimentation rate and particle diameter of animal waste, the coefficients n, b and standard deviation were calculated as shown in Table 3.
7) Particle density ρ
s of animal waste in saturation state was obtained from the distribution of sedimentation rate and the particle diameter of the same sample, and the relation between ρ
s and the particle diameter was shown in Fig. 8 and Fig. 9. The value ρ
s of pig slurry had a small difference from solvent density ρ
1 and almost uniform through all the particle range. The value ρ
s of cattle slurry was somewhat larger for middle size particles of about 50μ.
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