As urbanisation continues to grow across Australia, so does the challenge of managing stormwater runoff. Rainfall that lands on impervious surfaces such as roads, rooftops, and pavements quickly becomes stormwater, carrying with it a cocktail of pollutants including sediments, oils, nutrients, metals, and pathogens. If left untreated, this runoff flows directly into local waterways, impacting aquatic ecosystems, public health, and infrastructure. Effective stormwater treatment is therefore not only an environmental necessity but also an essential part of sustainable urban and industrial planning.
What is Stormwater Treatment?
Stormwater treatment refers to the various methods and technologies used to remove pollutants and manage flow volumes in stormwater before it reaches natural water bodies or re-enters the water cycle. The goal is to:
- Reduce pollution entering rivers, lakes, and oceans
- Control erosion and flooding
- Improve groundwater recharge
- Enhance overall water quality and biodiversity
Stormwater treatment can be implemented at different stages, from source control to end-of-pipe treatment and often integrates both natural and engineered systems.
Major Sources of Stormwater Pollution
Stormwater pollution arises from a range of urban, industrial, and agricultural activities. Common contaminants include:
- Sediments from construction sites and eroded land
- Nutrients like nitrogen and phosphorus from fertilizers
- Heavy metals such as zinc, copper, and lead from vehicle wear and roofs
- Oils and hydrocarbons from roads and industrial sites
- Pathogens from animal waste and sewage overflows
Understanding these sources helps in designing appropriate treatment solutions that target site-specific risks.
Key Stormwater Treatment Methods
Stormwater treatment systems are most effective when multiple processes are used in sequence, forming a treatment train that captures a broad range of pollutants. Below is a breakdown of the most widely used stormwater treatment methods and their performance characteristics:
1- Gross Pollutant Traps (GPTs)
Function:
Capture large solid waste such as litter, leaves, and coarse sediments before they can enter drainage or downstream treatment systems.
Applications:
Ideal for urban areas with high litter loads, car parks, roads, and commercial/retail sites.
Performance:
- Removes up to 70β90% of gross pollutants by volume
- Reduces downstream blockages and sediment build-up
- Low maintenance when correctly sized and positioned
AIMEQUIP Advantage:
Our GPTs are engineered for high hydraulic capacity with easy access for vacuum or manual clean-out, reducing service downtime.
2- Sedimentation and Clarification Systems
Function:
Remove suspended solids by slowing water velocity to allow particles to settle. May be enhanced by chemical coagulation or flocculation to improve efficiency.
Applications:
Industrial facilities, construction sites, high-sediment runoff areas.
Performance:
- Removes 60β80% of total suspended solids (TSS) without additives
- Enhanced systems with flocculants can reach >90% TSS removal
- Effective in pre-treatment before filtration or biological stages
AIMEQUIP Advantage:
We offer both passive and active sedimentation systems, with chemical dosing integration for enhanced performance.
3- Filtration Systems
Function:
Physically remove finer sediments and dissolved pollutants by passing water through filtering media such as sand, activated carbon, or proprietary composites.
Applications:
Urban catchments, commercial sites, light industrial areas, retrofit solutions.
Types:
- Sand filters β Cost-effective and easy to maintain
- Media filters β Target specific pollutants (e.g., heavy metals, hydrocarbons)
- Cartridge systems β Modular and scalable for confined spaces
Performance:
- 70β95% removal of TSS and hydrocarbons
- Reduces nutrients such as phosphorus and nitrogen
- Custom media can achieve up to 90% heavy metal removal
AIMEQUIP Advantage:
We design modular filtration units that can be site-fitted or retrofitted with minimal civil works, ensuring fast deployment and long service life.
4- Biological Treatment Systems (Biofiltration & Wetlands)
Function:
Use vegetation, soil, and microbial activity to treat stormwater through natural processes like adsorption, nutrient uptake, and biodegradation.
Applications:
Urban developments, green infrastructure, industrial sites with space for surface systems.
Types:
- Raingardens / Bioretention basins β Filter water through vegetated media
- Constructed wetlands β Provide extended retention and ecological co-benefits
- Swales and vegetated channels β Manage flow and improve infiltration
Performance:
- Up to 95% nutrient removal (nitrogen & phosphorus)
- >80% reduction in pathogens and biological oxygen demand (BOD)
- Enhances biodiversity, aesthetics, and site cooling
AIMEQUIP Advantage:
Our engineered biofiltration units are space-efficient, fully scalable, and compatible with urban landscapes or industrial grounds.
5- Chemical Dosing and Smart Control Systems
Function:
Add reagents (e.g., alum, PAC, pH buffers, polymers) to alter water chemistry for pollutant precipitation, neutralisation, or floc formation.
Applications:
Mining, manufacturing, food processing, and other high-risk sites with strict discharge requirements.
Performance:
- >90% phosphorus removal using alum or ferric salts
- pH adjustment within environmental discharge limits (typically 6.5β8.5)
- Effective for emulsified oils, heavy metals, and colour reduction
Smart Integration:
Real-time flow monitoring and automatic dosing based on sensor feedback ensures optimal chemical usage and avoids overdosing.
AIMEQUIP Advantage:
We provide plug-and-play dosing skids with flow pacing, telemetry, and alarm systemsβreducing compliance risk and operating cost.
6- Stormwater Harvesting and Reuse Systems
Function:
Collect and store treated stormwater for reuse in irrigation, industrial wash-down, or cooling applications.
Applications:
Commercial buildings, parks, industrial facilities, municipalities.
Performance:
- Reduces reliance on mains water
- Cuts operating costs for non-potable water usage
- Reduces downstream pollutant loads by re-routing runoff
AIMEQUIP Advantage:
We integrate storage, filtration, and UV disinfection into a single skid-based unit for ease of installation and operation.
Summary of Treatment Method Performance (Typical Ranges)
Method | TSS Removal | Nutrient Removal | Hydrocarbon Removal | Heavy Metal Removal |
Gross Pollutant Traps | 70β90% | Low | Low | Low |
Sedimentation + Floc | 60β95% | Moderate | Low | Moderate |
Filtration Systems | 70β95% | Moderate | High | High |
Biofiltration/Wetlands | 80β95% | High | Moderate | Moderate |
Chemical Dosing Systems | 90β99% | High | Moderate to High | High |
Harvesting + UV Treatment | Varies | Low | High (with pre-filtration) | Low to Moderate |
The Role of Smart Engineering in Stormwater Management
Modern stormwater treatment isnβt just about complianceβitβs about performance, resilience, and sustainability. Advanced control systems allow real-time monitoring of flow rates, rainfall data, and pollutant levels. Integration with IoT (Internet of Things) technology helps facilities optimise chemical dosing, reduce maintenance, and predict overflow risks before they happen.
AIMEQUIP’s Commitment to Better Stormwater Solutions
At AIMEQUIP, we offer tailored stormwater treatment systems that combine innovation, reliability, and efficiency. Our offerings include:
- Solid separation systems that remove heavy particles and gross pollutants
- Automated chemical dosing units for accurate pollutant control
- Turnkey stormwater treatment packages designed for industrial, municipal, and commercial applications
- Ongoing service and maintenance to ensure long-term performance and regulatory compliance
Whether you are managing a large industrial discharge or an urban development site, our engineering team works closely with clients to deliver end-to-end solutions that align with both environmental standards and operational needs.