Sand Washing Wastewater Treatment

Introduction

During the sand washing process, a large amount of impurities such as clay and stone powder are washed out from the raw sand, forming highly concentrated muddy water. Direct discharge of this water would not only cause serious environmental pollution but also lead to the waste of water resources. The use of a filter press can effectively treat the slurry mixture generated from sand washing, achieving efficient solid-liquid separation, facilitating the recycling of water resources, and enabling the standardized disposal of solid waste.

Sand Washing Wastewater Treatment Process

In the sand washing industry, chamber filter presses and plate-and-frame filter presses are the most commonly used dewatering equipment, both operating on similar principles.

Process Overview:

Feeding: Concentrated slurry is pumped under high pressure into sealed chambers formed by filter plates.
Filtration: Under pressure, water passes through the filter cloth and is discharged as clear filtrate, while solid particles are retained in the chambers, forming filter cakes.
Squeezing (Optional): To further reduce moisture content, many filter presses are equipped with a secondary squeezing mechanism (e.g., membrane squeeze). After feeding, high-pressure water or air is injected into the membranes to compress the cakes and express additional liquid.
Cake Discharge: Upon cycle completion, the plates separate, and the dried cakes discharge by gravity onto a conveyor below.

Advantages of Using Filter Presses in Sand Sludge Treatment

Effective Treatment: Cake moisture content can be reduced to 25%–35%, forming hard, easily transportable blocks that release no water when squeezed.
High Water Recovery Rate: The separated water is clear with low suspended solids and can be directly recycled into the production process.
High Automation: Modern filter presses operate fully automatically, including plate shifting, cake discharge, and cloth cleaning, significantly reducing labor requirements.
Strong Adaptability: They perform well under varying feed conditions; adjusting flocculant dosage allows treatment of different sludge types.

Key Operational Considerations

Flocculant Selection: Polyacrylamide (PAM) is typically added before filtration to agglomerate fine particles into larger flocs, improving filtration rate and reducing cake moisture.
Filter Cloth Selection: Cloth material and pore size directly impact efficiency and service life—selection should match particle characteristics and pH of the sludge.
Pump Requirements: High-pressure, high-flow plunger or screw pumps are essential to overcome rising filtration resistance.
Routine Maintenance: Regular cloth cleaning/replacement and inspection of hydraulic and electrical systems ensure long-term stable operation.