Water Treatment Chemicals
02 May 2025
In Singapore, where clean water is a strategic resource, effective wastewater treatment is critical to both public health and sustainable industrial development. As industries such as textiles, electronics, and chemicals continue to grow, so does the complexity of the waste they generate. Industrial effluents often contain suspended solids, dyes, oils, and heavy metals that cannot be treated through basic filtration alone. This is where chemical coagulants like Polyaluminium Chloride (PAC) play an essential role.
PAC has emerged as a leading coagulant for industrial wastewater treatment due to its high efficiency, low sludge production, and adaptability across a wide range of wastewater compositions. This article explores its mechanism, application benefits, and how it aligns with Singapore’s long-term water sustainability goals.
Polyaluminium Chloride (PAC) is an inorganic polymer-based coagulant composed of aluminum, chlorine, and hydroxyl groups. It exists in various forms, including liquid and powder, and is widely used in the clarification of water due to its ability to destabilize suspended particles quickly and effectively.
PAC has a higher charge density compared to traditional coagulants like aluminum sulfate (alum), making it more efficient in binding fine particles and organic matter. This higher charge facilitates stronger flocculation, resulting in faster sedimentation and cleaner treated water. In Singapore’s advanced water treatment ecosystem, PAC is increasingly preferred due to its minimal impact on pH, reduced need for pH correction chemicals, and overall operational cost efficiency.
Industries in Singapore are under strict regulations imposed by the Public Utilities Board (PUB) regarding effluent discharge. PAC helps these industries meet discharge quality requirements while also supporting water recycling and resource conservation practices.
For instance, textile industries generate effluents with high chemical oxygen demand (COD) and intense coloration due to dye usage. PAC has proven effective in removing both color and organic load, significantly improving water clarity and quality. Similarly, in semiconductor manufacturing, which produces high levels of ultra-fine particles and heavy metals, PAC facilitates the aggregation and removal of these harmful substances.
Furthermore, the compactness and efficiency of PAC treatment systems align with Singapore’s land constraints. Many industrial facilities operate in limited spaces where the footprint of treatment units must be minimized.
The primary action of PAC is based on coagulation and flocculation. These are two sequential processes that are central to most wastewater treatment systems:
Coagulation
When PAC is added to wastewater, the positively charged aluminum species neutralize the negative charges on colloidal particles. This neutralization destabilizes the colloids, reducing their mutual repulsion and allowing them to aggregate.
Flocculation
After coagulation, gentle mixing encourages the small destabilized particles to collide and form larger aggregates or flocs. These flocs are then easily removed by sedimentation or filtration.
The effectiveness of PAC in this dual process results in a substantial reduction in turbidity, organic load, and color.
The textile industry is a significant user of water and produces large volumes of highly colored and chemically complex wastewater. PAC is widely used in textile effluent treatment due to its superior ability to remove dyes, especially reactive and disperse dyes which are otherwise difficult to eliminate.
PAC’s ability to work under various pH levels and wastewater compositions allows it to treat both acidic and alkaline textile waste. Moreover, it forms dense flocs that settle quickly, enabling faster treatment cycles and better recovery of treated water for reuse.
This is particularly valuable in Singapore’s water-scarce environment where closed-loop systems are encouraged, and industries are expected to contribute to water sustainability through reuse and recycling.
In food and beverage industries, wastewater typically contains high levels of organic matter, fats, oils, and grease. PAC is utilized in primary and secondary treatment phases to reduce COD and suspended solids.
The high adsorption capacity of PAC makes it efficient in capturing colloidal organic particles. When used in combination with biological treatment or dissolved air flotation (DAF), PAC enhances overall process efficiency and leads to better effluent quality.
Industries using PAC also benefit from reduced sludge volumes, leading to lower sludge handling and disposal costs, an important consideration in Singapore’s high-cost industrial landscape.
Electronics manufacturing processes generate wastewater containing a variety of heavy metals and fine particulates. PAC’s strong flocculation ability enables the removal of contaminants such as copper, lead, zinc, and arsenic.
In chemical plants, where pH and ionic strength of wastewater may vary, PAC remains effective due to its stable performance across a wide pH range (typically pH 5–9). Its fast reaction time also shortens overall treatment durations, helping industries meet real-time discharge compliance requirements.
PAC’s compatibility with other treatment processes like reverse osmosis (RO) or membrane filtration makes it a valuable pre-treatment agent, protecting downstream equipment from fouling and scaling.
The use of PAC leads to a range of environmental and economic benefits, especially important for resource-efficient countries like Singapore:
Reduced Chemical Dosage: PAC requires a lower dosage than alum to achieve similar or better results.
Lower Sludge Volume: Less sludge means reduced transportation and disposal costs.
Enhanced Water Reuse: Cleaner effluent facilitates easier recycling within facilities.
Stable Performance: Reliable results regardless of seasonal water composition changes.
These benefits contribute to achieving Singapore’s “Four National Taps” water strategy, particularly the NEWater initiative, which relies heavily on the high-quality pre-treatment of industrial effluents.
PAC continues to evolve with innovations focusing on increasing its efficiency and sustainability. Recent developments include:
Nano-PAC: Enhanced coagulation efficiency using nano-sized particles for better surface interaction.
Hybrid PAC Formulations: Blends with polymers or activated carbon for dual-function coagulation and adsorption.
Green Synthesis Methods: Research into producing PAC from recyclable aluminum waste to reduce carbon footprint.
Singapore’s focus on circular economy principles is likely to accelerate the adoption of such advanced formulations. Regulatory incentives may also support industries that switch to greener water treatment options.
Polyaluminium Chloride plays a central role in the efficient treatment of industrial wastewater in Singapore. Its high coagulation efficiency, low sludge output, and adaptability to a wide range of effluents make it an ideal solution for industries ranging from textiles to semiconductors.
By helping industries meet stringent discharge standards and supporting water recycling, PAC contributes to Singapore’s broader goals of water sustainability and industrial resilience. As new formulations and treatment technologies emerge, the role of PAC in the wastewater sector is poised to expand further, reinforcing its position as a critical component in modern water management strategies. If you are interested in our products for your specific business needs, please do not hesitate to contact us.
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