Disintegration of Waste Activated Sludge by Thermally-Activated Persulfates for Enhanced Dewaterability

Phosphorus is a nonrenewable and irreplaceable limited resource, and over 90% of phosphorus in influenttransfers into sludge in wastewater treatment plants. In this study, thermally activated peroxydisulfate (TAP) treatment was combined with struvite precipitation to enhance waste activated sludge (WAS) dewaterability and phosphorus recovery. TAP simultaneously enhanced dewaterability and solubilization of WAS. The optimal conditions of TAP treatment were PDS dosage 2.0 mmol/g TSS, 80 °C, pH 4.0~7.0 and 40 min, which enhanced dewaterability (capillary suction time (CST) from 94.2 s to 28.5 s) and solubilization (PO43−-P 177.71 mg/L, NH4+-N 287.22 mg/L and SCOD 10754 mg/L). Radical oxidation disintegrated tightly bound extracellular polymeric substances (TB-EPS) and further released bound water. The acidification effect neutralized the negative surface charge of colloid particles. Compared with thermal hydrolysis, TAP effectively promoted the release of PO43−, NH4+ and SCOD. Cation exchange removed most Ca and Al of the TAP treated supernatant. The optimal conditions of struvite precipitation were Mg/P 1.4 and pH 10.0, which achieved phosphorus recovery of 95.06% and struvite purity of 94.94%. The income obtained by struvite adequately covers the cost of struvite precipitation and the cost of WAS treatment is acceptable.

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Insight into dewatering behavior and heavy metals transformation during waste activated sludge treatment by thermally-activated sodium persulfate oxidation combined with a skeleton builder—wheat straw biochar

Chemosphere ◽

10.1016/j.chemosphere.2020.126542 ◽

2020 ◽

Vol 252 ◽

pp. 126542 ◽

Cited By ~ 3

Author(s):

Junyuan Guo ◽

Qifan Gao ◽

Shilin Jiang

Keyword(s):

Heavy Metals ◽

Activated Sludge ◽

Wheat Straw ◽

Waste Activated Sludge ◽

Sodium Persulfate ◽

Sludge Treatment ◽

Persulfate Oxidation ◽

Thermally Activated ◽

Insight Into ◽

Skeleton Builder

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Comparison of Aerobic and Anoxic-Aerobic Digestion of Waste Activated Sludge

Water Science & Technology ◽

10.2166/wst.1985.0068 ◽

1985 ◽

Vol 17 (8) ◽

pp. 1475-1478 ◽

Cited By ~ 6

Author(s):

A P. C. Warner ◽

G. A. Ekama ◽

G v. R. Marais

Keyword(s):

Experimental Data ◽

Activated Sludge ◽

Waste Activated Sludge ◽

Activated Sludge Process ◽

Cycle Times ◽

Waste Sludge ◽

Volatile Solids ◽

In Series ◽

Flow Through ◽

Theoretical Simulations

The laboratory scale experimental investigation comprised a 6 day sludge age activated sludge process, the waste sludge of which was fed to a number of digesters operated as follows: single reactor flow through digesters at 4 or 6 days sludge age, under aerobic and anoxic-aerobic conditions (with 1,5 and 4 h cycle times) and 3-in-series flow through aerobic digesters each at 4 days sludge age; all digesters were fed draw-and-fill wise once per day. The general kinetic model for the aerobic activated sludge process set out by Dold et al., (1980) and extended to the anoxic-aerobic process by van Haandel et al., (1981) simulated accurately all the experimental data (Figs 1 to 4) without the need for adjusting the kinetic constants. Both theoretical simulations and experimental data indicate that (i) the rate of volatile solids destruction is not affected by the incorporation of anoxic cycles and (ii) the specific denitrification rate is independent of sludge age and is K4T = 0,046(l,029)(T-20) mgNO3-N/(mg active VSS. d) i.e. about 2/3 of that in the secondary anoxic of the single sludge activated sludge stystem. An important consequence of (i) and (ii) above is that denitrification can be integrated easily in the steady state digester model of Marais and Ekama (1976) and used for design (Warner et al., 1983).

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