# The Effects Of CKD On Sludge Stabilization

Table (3) pH for treated sludge with CKD and Lime

Sludge type TS% CDK dosage (%TS) pH*

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At any operating time the sludge interface height for treated sludge is lower than that for untreated sludge. The Zone settling velocity is determined as the slope of the linear part, which in the calculations is defined as the steepest slope in the curve [16], Based on this criteria the zone settling velocity increased from 43.2(m/d) for untreated sludge to 98.4(m/d) for treated sludge, for factor of safety equal to 2 the hydraulic loading rate of gravity thickeners will be 21.06 (m/d), and 49.20 (m/d) for the untreated and treated sludge

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Results of treated sludge complies with the results published by EPA [4] as they found that only two days are enough for treated sewage sludge with lime and some other conditioners to get sludge solid content varied between 20 and 30%.

Figure (6) shows the relation between drying time and sludge pH value, the results treated sludge shows that the pH value remains above 10.50 for the whole test which lasts for 5 days. This result complies with the results of Salah [12] who studied using CKD as stabilizer for thickened and dewatered sludge and found that using CKD with dosage more than 30% increased the pH value to be 11 for 7 days.

3.5 Additional Sludge