| Abstract |
| In terms of settleability improvement additives (SIAs), a weighted coagulation phenomenon is divided into two types of sedimentation. SIAs that did not penetrate into the microbial floc settled rapidly through the flocs by its own weight, and the remaining SIAs penetrated into the microbial floc slowly settles with these flocs, which can be confirmed by volume reduction ratio (VRR). This study was performed to evaluate the new settleability improvement technology using an activated carbon made of sewage sludge (ACsludge) powder as SIAs for sludge volume reduction in the secondary clarifier. Under the condition of MLSS 4,500 mg/L, as a result of evaluating the change of sedimentation pattern according to the amount of dosage by using two kinds of ACsludge with different particle size, it can be confirmed that VRR increases as the amount of dosage increases regardless of the particle size characteristics. As a result of evaluating the amount of residual activated carbon (Residual-ACsludge) as unfixed into the microbial floc, it was found that the amount of Residual-ACsludge also increased as the amount of ACsludge increased. In addition, M II (large size and heavy) was found to have a larger amount of ACsludge, which unfixed with microbial floc than M I (small size and light). In order to evaluate the stirring speed and the mixing time affected on the value of VRR change, 2 g/L of M I and M II were dosages and monitored under conditions of 4,100 mg/L of MLSS. As a result of the experiment, the increase of the stirring speed could increase the VRR, but the increase of the stirring time was found to have no effect on the increase of the VRR. To find the optimum conditions, sedimentation experiments were conducted with various concentrations of MLSS under standard condition (2 g/L of M I and M II, 150 rpm, 5 min.). Both M I and M II showed highest VRR at 4,500 mg/L of MLSS. From a strategic point of view, it was considered that the use of M I was effective at concentrations below 4,500 mg/L of MLSS, and M II was more effective under conditions above 4,500 mg/L of MLSS, respectively. |
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| Key Words |
| Activated carbon made of sewage sludge, Residual activated carbon, Settleability improvement additives, Volume reduction ratio |
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