Let’s Talk Gross Pollutant Traps: Types of GPTs

A gross pollutant trap (GPT) – categorized as a Primary Treatment Device, is the first line of defense in a stormwater treatment system and removes much of the bulky pollutants from stormwater runoff.

Traditionally we find GPTs fending off litter, cigarette butts, plastic bottles, leaves and sediment. A strong, robust GPT plays a key role in ensuring Tertiary Treatment Devices like biofilters, raingardens and proprietary filters can ‘polish’ or clean the stormwater, removing an additional layer of particles and dissolved pollutants.

Which Gross Pollutant Traps Work Best?

There are several different GPTs in the market today – all removing gross pollutants from our stormwater system in different ways. Most GPTs fall into one of the below categories:

Difference in specific gravity traps
Systems which use gravity to separate pollutants that float and settle without the use of screens. Water quality is achieved by incorporating baffles/booms in a series of chambers.

Direct screening
Devices which incorporate screens in various orientations to manage the flow. These are not self-cleansing.

Vortex type devices
Devices that direct flow to produce vortices/hydrodynamic separation, but do not have a screen.

Devices that combine a vortex/hydrodynamic separation with a non-blocking screening system
The SPEL Vortceptor GPT (now known as the Atlan Vortceptor) is a vortex separation unit with a non-blocking screen system.

The Vortceptor

Innovations in stormwater technology have produced modern GPTs, but concrete units are typically costly to install, lift, and freight.

In 2019 SPEL release the Vortceptor – a light weight, one-piece alternative to the current concrete tanks. This exclusively designed and manufactured GPT with a hydrodynamic separator producing vortex conditions, resulted in excellent pollutant removal ratings and high-quality outcomes.

With its non-blinding screen, the Vortceptor was cutting edge technology. As founder Stephen Hales recalls ‘we knew we had a good product. This lightweight, easy to install system would save our customers time and money.’

SPEL manufactures the Vortceptor as a single-piece, pre-assembled fibreglass  chamber. No laborious on-site assembly. No hefty installation costs. The remarkable strength to weight ratio achieved by this structure gives us a product a fraction of the weight, while still structurally robust underground. Fibreglass is also durable and resistant to chemicals, saltwater acid sulfate soils.

Timeless Innovation: Two Decades On

The world of GPTs has changed dramatically since the mid 90’s. While technology has advanced and improvements have been made, the principals of GPT technology and pollutant capture have remained timeless. SPEL continues to innovate, looking for further improvements and field testing on the Vortceptor.

As Stephen Hales would say ‘it’s a constant evolution’ – bringing us closer every day to the clean water future we all envisage.

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