Enhancing dewaterability of sewage sludge by the application of tween-20 during bioleaching: Performance evaluation and mechanistic study

ABSTRACT

Dewatering is recognized as an important method for treating sewage sludge before its disposal. In this paper, the nonionic surfactant Tween-20 was used for the first time to improve the dewaterability of sewage sludge during bioleaching. The specific resistance to filtration (SRF), water content (WC) and bound water content (BW) of the sludge cake were used to evaluate sludge dewaterability. The results indicated that a 1 g/L Tween-20 dosage with an inoculum ratio of 20%, a S⁰ dosage of 2 g/L and a FeSO₄ · 7H₂O dosage of 10 g/L provided oxidation efficiencies up to 100% for Fe²⁺ and 65.8% for S⁰. The SRF of the bioleached sludge decreased to as low as 0.81 × 10¹² m/kg from the initial 12.6 × 10¹² m/kg for raw sludge. A WC of 47.16% was achieved while 48.1% of BW was released during bioleaching. The results from this study indicate that adding of an appropriate amount of Tween-20 to sewage sludge is a promising method to enhance dewaterability by bioleaching.

KEYWORDS:

• Bioleaching
• bound water
• dewaterability
• sewage sludge
• Tween-20

Additional information

Funding

The present study was supported jointly by the Basic and Frontier Technology Research Project of Henan Province Science and Technology Department of China (1152300410036), the Key Research Projects of Henan Province Education Department of China (15A610020), and Key Research Projects of Henan Province Science and Technology Department of China (162107000018).