Advanced Surface Water Treatment to Drinking Water Standards

Surface water treatment is often underestimated in its complexity. Unlike groundwater, surface water is a dynamic and biologically active system that presents a wide range of treatment challenges.

These include:

• Highly soluble colour from fulvic and humic acids

• Algae and biological growth

• Extracellular polymeric substances (EPS)

• Bacteria and pathogens

• Colloidal matter

• Signific

  ant seasonal fluctuations

In essence, surface water behaves like a living system, continuously changing and inherently prone to biological fouling throughout the treatment process.

Traditional single-stage or conventional media-based treatment systems are often insufficient to consistently achieve potable water standards from such a complex source. Recognising this challenge, we were tasked with developing a compact and robust treatment solution capable of producing drinking water year-round under varying raw water conditions.

A Multi-Barrier Treatment Approach

Our approach focused on a layered, multi-barrier treatment philosophy, integrating both physico-chemical and membrane processes to ensure reliable performance.

The treatment train begins with the restructuring of dissolved organic compounds using ozone-assisted coagulation. This step improves the treatability of otherwise stable dissolved organics and enhances downstream removal efficiency.

Coagulation and Solid Separation

Coagulation is carefully controlled through precise pH adjustment to optimise sweeping floc formation using polyaluminium chloride (PAC).

Key process conditions include:

• Controlled pH optimisation

• Approximately 15–20 minutes of contact time for effective floc development

• Efficient separation using a lamella plate settler

The lamella plate settler is designed with controlled vertical velocities to maximise solids removal while maintaining a compact system footprint.

Polishing Through Media Filtration

Following clarification, the process includes a pressurised media filtration stage.

This stage serves as a polishing and screening step, capturing any residual particulate carryover before the water enters the membrane stage.

Media filtration is particularly effective in modular systems where footprint and operational simplicity are key design considerations.

Ultrafiltration: The Core Pathogen Barrier

At the core of the system is ultrafiltration (UF), which acts as the primary barrier to pathogens.

With a nominal pore size of approximately 0.04 microns, UF membranes are capable of removing:

• Bacteria

• Most viruses

• Fine suspended particles

This provides a high level of mechanical disinfection, significantly reducing downstream chlorine demand while minimising the formation of disinfection by-products.

The result is consistent and reliable drinking water quality.

Enhanced Organic Removal

An additional benefit arises from the interaction between coagulant residuals and the hydrophilic membrane surface.

This interaction creates a dynamic layer on the membrane, which enhances the rejection of dissolved organics and colour.

As a result, the system can outperform conventional treatment methods, particularly when treating complex surface water sources.

Monitoring and Process Control

To ensure reliability and performance, the system is supported by continuous online monitoring and precise process control across all treatment stages.

This enables:

• Rapid response to raw water variability

• Consistent process optimisation

• Reliable compliance with drinking water standards

Proven Performance in the Field

The solution has been successfully deployed across multiple sites, operating continuously with:

• Greater than 95% uptime

• Minimal operator intervention

The result is a resilient, high-performance treatment system capable of transforming complex surface water sources into safe, high-quality drinking water.