Types of Wastewater Treatment Systems

Septic Tanks

How they work: Separate solids and liquids; solids settle and partially decompose; liquids discharge to a soakaway.

Best for: Low-occupancy homes with good subsoil percolation.

Regulation: No direct outflow to watercourses allowed post-2020 EA rules unless upgraded.

Popular brands: Marsh, Klargester, Matrix, Graf & Tricel

Sewage Treatment Plants (STPs)

 

How they work: Use mechanical aeration to biologically break down waste; clean effluent is discharged to a watercourse or soakaway.

Best for: Domestic and commercial sites with no mains drainage.

 

Types:

ASP (Activated Sludge Process) – common and reliable.

SBR (Sequencing Batch Reactors) – great for nutrient removal (e.g. Marsh Nutra-Lite).

BioDisc/Rotating Biological Contactors – low noise, low energy (e.g. Klargester).

Compliance: Must meet BS EN 12566-3 for CE/UKCA marking.

Cesspools / Holding Tanks

How they work: Fully sealed tank – no treatment, just storage.

Best for: Temporary use or environmentally sensitive zones with no discharge permission.

Downside: Expensive due to regular emptying.

Pump Stations

Purpose: Move wastewater uphill or over distance to treatment/discharge.

Types:

Single or dual pump.

With high-level alarms and float switches.

Use case: Basements, low-lying properties, caravans.

Phosphate & Nitrate Removal Filters

Why needed: EA requires nutrient removal in sensitive catchment zones.

Solution: Systems like Phos-Lite or Nutra-Lite (Marsh) meet nutrient discharge consents.