Enhancing Phosphorus Recovery and Dewaterability of Waste Activated Sludge for Combined Effect of Thermally Activated Peroxydisulfate and Struvite Precipitation

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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Extracellular polymeric substances and dewaterability of waste activated sludge during anaerobic digestion

Water Science & Technology ◽

10.2166/wst.2014.401 ◽

2014 ◽

Vol 70 (9) ◽

pp. 1555-1560 ◽

Cited By ~ 11

Author(s):

Fenxia Ye ◽

Xinwen Liu ◽

Ying Li

Keyword(s):

Anaerobic Digestion ◽

Activated Sludge ◽

Extracellular Polymeric Substance ◽

Extracellular Polymeric Substances ◽

Waste Activated Sludge ◽

Sludge Dewatering ◽

Capillary Suction ◽

Relationship Analysis ◽

The Relationship ◽

Insight Into

Anaerobic digestion of waste activated sludge was conducted to gain insight into the mechanisms underlying change in sludge dewaterability during its anaerobic digestion. Unexpectedly, the results indicated that sludge dewatering properties measured by capillary suction time only deteriorated after 10 days of anaerobic digestion, after which dewaterability recovered and remained stable. The loosely bound extracellular polymeric substance (LB-EPS) content increased three-fold after 20 days of anaerobic digestion, and did not change significantly during the remaining 30 days. The tightly bound EPS (TB-EPS) content reduced slightly after 20 days of anaerobic digestion, and stabilized during the last 30 days. Polysaccharides (PS) and proteins (PN) content in LB-EPS increased after 10 days of anaerobic digestion. However, PS and PN contents in TB-EPS decreased slightly. The relationship analysis showed that only LB-EPS correlated with dewaterability of the sludge during anaerobic digestion.

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The Effects of Ultrasonic Disintegration as a Function of Waste Activated Sludge Characteristics and Technical Conditions of Conducting the Process—Comprehensive Analysis

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph15102311 ◽

2018 ◽

Vol 15 (10) ◽

pp. 2311 ◽

Cited By ~ 6

Author(s):

Malwina Tytła

Keyword(s):

Activated Sludge ◽

Energy Supply ◽

Extracellular Polymeric Substances ◽

Biogas Production ◽

Control Sample ◽

Treatment Plant ◽

Comprehensive Analysis ◽

Waste Activated Sludge ◽

Capillary Suction ◽

Constant Energy

A comprehensive analysis of the effects obtained in the process of ultrasonic disintegration (UD) of waste activated sludge (WAS), was conducted. Sludge samples were collected periodically from Central Wastewater Treatment Plant (WWTP) in Gliwice (Poland) and disintegrated in the two ultrasonic devices of different construction and technical parameters, i.e., WK-2010 (A) and ultrasonic washer (B). The experiments were performed under a constant energy supply per sludge volume EV = 160 kWh·m−3. The direct and technological effects, i.e., after UD and anaerobic digestion (AD) were investigated, respectively. Statistical analysis showed that characteristics and parameters of the WAS, which affects the magnitude of the direct effects create the following sequence: TS (total solids), VS (volatile solids), ΔT (temperature increase) > EPS (extracellular polymeric substances) > SCOD (soluble chemical oxygen demand) > CST (capillary suction time) > NTOT (total nitrogen), PTOT (total phosphorus) > pH. Whereas, in the case of technological effects, the above sequence was as follows: TS, VS > CST > NTOT, PTOT > pH. Ultrasonic disintegration of WAS prior to AD increased total biogas production (from 13.0% to 19.7%) and reduced the content of TS (from 4.1% to 8.2%) and VS (5.8% to 9.5%) in comparison to the control sample. This confirms the usefulness of ultrasonic disintegration as an effective method of sludge digestion intensification. The obtained results showed that changes in the characteristics of WAS have a significant impact on the magnitude of the effects of ultrasonic disintegration, especially TS, VS, ΔT, EPS, SCOD and CST. Concluding, it can be inferred that the most promising conditions for ultrasonic pretreatment conducted under constant energy supply per sludge volume, are: low power, long sonication time, large surface area of the emitter, and high increase of sludge temperature while conducting the process.

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