How HYDROS Works: A Step-by-Step Guide to the Treatment Process

For most facility operators and property managers, sewage treatment happens in the background. You know the system is there. You know it needs to work. But what actually happens between the point where raw sewage enters the system and the point where clean water comes out? 

Understanding the process matters more than it might seem. It helps operators maintain their systems correctly, set realistic expectations around water quality and monitoring requirements, and make better-informed decisions when evaluating sewage treatment options. This article explains exactly how HYDROS processes sewage, from pre-treatment through to final discharge.  

Pre-treatment: The Foundation 

Before sewage enters the HYDROS plant itself, it passes through two pre-treatment tanks. 

The first is a traditional septic tank, which serves as the initial stage of solids separation. As raw sewage enters, solid matter is trapped and begins to break down through a natural process called anaerobic digestion. In this oxygen-free environment, bacteria dissolve the organic solids, transforming them into a form that can be processed further down the treatment line. This stage does not produce clean water. Its job is preparation: reducing the solids load so that the biological treatment stages that follow can operate effectively. 

The second tank addresses a different challenge: surge flow. Sewage generation at most sites is not consistent. A school camp might have peak usage in the early morning and evening, with significantly lower volumes during the middle of the day. A caravan park experiences the same fluctuation. Feeding raw surges directly into the treatment plant would shock the biological system and compromise performance. The surge tank fills during peak periods and then doses water evenly throughout the day, protecting the downstream treatment stages from irregular loads and ensuring consistent, reliable performance regardless of usage patterns. 

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Phase 1: Biological Treatment 

Once the pre-treated wastewater enters the HYDROS system, it moves into aerated treatment tanks. Air is introduced into the water, creating an oxygen-rich environment that supports the growth of aerobic bacteria. These bacteria break down the primary organic contaminants, converting them to carbon dioxide and water in a process that mirrors what happens naturally in healthy ecosystems, but under controlled, accelerated conditions. 

A significant by-product emerges during this phase. Ammonia, which comes primarily from urine, is converted by the bacteria into nitrates. Nitrates are water-soluble and can be processed further, but they cannot simply be released into the environment in large quantities without causing harm to waterways and ecosystems. The treatment process is not finished yet. 

 Phase 2: Nitrogen Removal 

In the second phase, HYDROS creates a deliberate contrast to the oxygen-rich environment of Phase 1. Conditions are engineered to deprive the water of freely available oxygen. With their primary energy source restricted, the bacteria present in the system shift their behaviour. Mixed with fresh organic material to sustain their activity, they begin breaking down the nitrates produced in Phase 1, neutralising pH and releasing the nitrogen they extract as nitrogen gas. This process is called denitrification. Nitrogen gas makes up approximately 80% of the atmosphere and is entirely harmless. What was a potential water pollutant, becomes nothing more than air. 

Phase 3: Clarification 

With biological treatment complete, the treated water still contains the bacteria that carried out the treatment process. Phase 3 removes them through one of nature's most reliable mechanisms: gravity. As the water moves into the clarification stage, the bacteria, being heavier than the treated water, settle out naturally. The purified water, now referred to as clarified effluent, rises to the surface and is released, while the separated bacteria are retained within the system. 

Phase 4: UV Disinfection  

Before the clarified effluent leaves the system, it passes through ultraviolet disinfection. UV light penetrates and disrupts the DNA of any remaining microorganisms, rendering them unable to reproduce. No chemicals are introduced and no residues are created. This final stage adds an additional layer of assurance to the quality of the output, producing treated effluent that meets the water quality standards required for safe discharge or reuse. 

What Comes Out 

The effluent that leaves a HYDROS system is clean, treated water. Depending on site conditions and the relevant approvals in place, it can be discharged safely into the environment or put to practical use on site. 

Through Aubin's Scarce Resource Recovery (SRR) process, nutrients and minerals naturally retained in the treated water, including nitrogen, phosphorus, and potassium, can be used to support irrigation, soil health, and land regeneration on site. For remote communities, rural properties, and facilities operating in water-stressed environments, this transforms sewage treatment from a waste management obligation into a practical resource. 

Continuous Monitoring Throughout  

The treatment process described above does not operate without oversight. Every HYDROS system includes RoboLab, Aubin's remote-access automated water quality laboratory, which provides real-time monitoring data from within the plant. Results are accessible online at any time by both the facility operator and Aubin's engineering team. 

Alongside RoboLab, the WATCHDOG system continuously monitors every component of the plant. If anything shifts outside normal operating parameters, it is detected and flagged before it becomes a problem. The result is a treatment process that does not just perform well under normal conditions, but one that can be observed, verified, and corrected in real time, regardless of where the system is located. 

Why This Matters for Operators  

Understanding how HYDROS works is not just useful background knowledge. It is the foundation for getting the most out of the system. Operators who understand the treatment process are better positioned to maintain their system correctly, interpret their monitoring data, and communicate with their regulators with confidence. 

To learn more about how HYDROS could work for your site, contact the Aubin team at aubin.com.au or call 1800 921 464. 

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