Facilitating component separation and cascade resource utilization of sewer sludge using alkaline plant ash

Area of Science:

• Environmental Science
• Waste Management
• Materials Science

Background:

• Sewer sludge management is a growing concern.
• Efficient separation of organic and inorganic components is crucial for sludge utilization.
• Plant ash offers a potential solution for sludge treatment.

Purpose of the Study:

• To investigate the efficacy of plant ash in separating organic and inorganic substances from sewer sludge.
• To evaluate the impact of plant ash on sludge properties and organic matter stripping.
• To explore resource recovery potential from treated sludge.

Main Methods:

• Pretreatment of sewer sludge with plant ash.
• Analysis of volatile suspended solids (VSS) reduction and soluble chemical oxygen demand (SCOD) increase.
• Measurement of Zeta potential to assess particle surface interactions.
• Characterization of organic matter (proteins, polysaccharides, humic acids) in the liquid phase.
• Evaluation of dewatering properties (moisture content, capillary suction time (CST), specific resistance to filtration (SRF)).

Main Results:

• VSS reduction rate reached 30%, with SCOD increasing 4.62-5.67 times.
• Zeta potential dropped to -19.97 mV, enhancing organic stripping.
• Stripping of proteins, polysaccharides, and humic acids increased by 4.5, 2.5, and 2.9 times, respectively.
• Moisture content, CST, and SRF were reduced to 71.30%, 19.3 s, and 0.83 × 10^12 m/kg.
• Plant ash facilitated organic matter removal via alkaline disruption, ion exchange, and osmotic pressure.

Conclusions:

• Plant ash effectively separates organic and inorganic matter in sewer sludge.
• The process enhances sludge dewatering and facilitates resource recovery from both liquid and solid phases.
• This method presents a cost-effective and simple approach for ex-situ sewer sludge treatment and resource utilization in urban drainage systems.