What is the difference between ‘Effluent Standard’ & ‘Stream Standard’ in sewage treatment?

Thank you for your question on the difference between the final effluent standard produced by a package sewage treatment plant and the stream standard.

The difference between the 2 is as follows:

1. Effluent Standard or Final Effluent Standard is the standard of effluent that a given wastewater treatment plant (WWTP) needs to produce based on a set maximum inlet load in terms of Flow, BOD, SS (Suspended Solids) & Ammonia (NH4), Nitrate (NO3), Nitrite (NO2), Total Nitrogen (TN), Orthophosphate (OP) and Total Phosphate (TP) if specified.  The outlet effluent parameters are set relative to the influent parameters.  N.B. Industrial effluent may have other parameters listed.  Package sewage treatment is concerned with the treatment of normal domestic sewage or equivalent.

2. The Stream standard is the standard of the water in a particular water course to which a sewage treatment plant is discharging into.  If a stream standard exists the Effluent standard for a particular WWTP is set by working back from the Stream standard.  For example if a water course is used for drinking water, bathing or as a fishery, the stream standard and thus the effluent standard discharging into that stream will be set relatively high and will probably include low BOD/SS and NH4/TN/TP concentrations.

However, if a watercourse can provide significant dilution/biodegradation then the stream standard can be set lower, thus resulting in a lower effluent standard.

The stream standard is often set relative to the ‘assimilative capacity’ of a watercourse.  This means how much dilution/biodegradation it can provide before pollution such as Oxygen stripping or eutrophication results.

A bit about the company

BMS is a quality manufacturer of package products for wastewater and stormwater treatment. BMS started in 1986 and has exported products to over 50 countries around the world.  It is a third generation family business with huge expertise in wastewater and stormwater.
BMS also manufacture a full range of products for surface water and wastewater treatment including our pioneering next generation RBC system the Aerotor, which forms part of our world leading Blivet package sewage treatment plant, a ‘one stop shop’ for all surface water products from design to installation including attenuation, interceptors, holding tanks (incl. chemical resistant), hydrobrakes, rainwater harvesting tanks & vortex silt/oil/debris separators, fully fitted pumping stations, our plug & play vehicle wash water recycling system; the Recyclone and much more.  Please see our enclosed Company & Product Profile for a full summary or View our full product/services catalogue at this link

BMS also can provide a Free Design Service for Sewage Treatment, Pump Stations or Surface Water and a full O&M, Repair, Advice and Testing service for existing installations.  We also can do free CPD Presentations on Sewage Treatment/Surface Water Management at any location.  Let us know when suits.

We would be delighted to discuss any requirements you might have, and we are available to meet you at your convenience.  Please do not hesitate to contact us.