Wastewater and water reuse; what you need to know

By: James Greenwood on Dec 3, 2020

If you’re not treating or re-using your commercial wastewater effectively you could be literally flushing money away. Realising cheaper disposal costs and the benefits of the ‘circular economy’ through smarter treatment of waste water is a significant opportunity. Here’s what you need to know.

Disposing of wastewater

Disposing of industrial or ‘process wastewater’ into public sewers requires permission from your sewage company and attracts a so-called "Trade Effluent Charge”.

This is mandated by the government and is an increasing burden on some business. But it has proved a vital tool for regulators as they try to mitigate the cost and impact of cleaning our rivers and watercourses of damaging pollutants.

The level of any TE charge is dependent on effluent volume and quality. Put simply: the greater the volume and the more polluting your discharge - the greater the cost.

Many companies in the dairy, food manufacture, rendering, brewing and distillery sectors now pay more for the disposal of their wastewater than for the fresh water they consume.

Where there’s muck...

But the good news is, if you can improve the cleanliness of your wastewater and effluent, then you can significantly reduce your discharge costs. And if you can clean it up sufficiently to re-use it, then you can start deriving real, long term value from your waste.

What are the 3 phases of successful water treatment?

Primary treatment

This is the first phase of water treatment. Wastewater is placed in holding tanks and solids settle to the bottom where they are collected. Fats and oils are then scraped off the top and the remaining liquid sent on for secondary treatment, meanwhile leftover sludge (when treated separately) can be used for other commercial purposes.

Dissolved Air Flotation (DAF) is one primary treatment that can be used to concentrate and remove a wide range of suspended solids in wastewater.

Meanwhile, the Volute Dewatering Press is a machine that enables sludge thickening and dewatering as part of the primary and secondary treatment cycles.

Both these processes can be critical for the removal of contaminants that could negatively impact an industrial biological wastewater treatment system downstream.

Secondary treatment

This phase makes use of oxidation to further purify wastewater.

Coagulants and flocculant chemicals are used in this phase for

  • further solids removal
  • water clarification
  • lime softening
  • sludge thickening
  • solids dewatering.

Coagulation destabilises the suspended particles,while flocculation helps them to bind together so they can be filtered out of the water more effectively.

PoIymers are a large range of natural or synthetic, water-soluble, macromolecular compounds that can destabilize or enhance flocculation of the constituents of a body of water.

Water treatment with these chemicals and processes can result in up to 90% reduction in suspended solids and organic loads, thus reducing the strength and volume of the wastewater for discharge and, therefore, associated disposal costs.

Tertiary water treatment

This phase is used to improve the quality of the effluent resulting from primary and secondary treatment processes.

After the tertiary treatment, water can be safely discharged into the environment, It can also be used for agricultural, industrial and, in some cases, domestic purposes:

  • Sand filtration can be used to remove particulate matter.
  • Enhanced biological phosphorus removal can be deployed
  • Nitrogen can be removed by using nitrifying bacteria.
  • Lagooning can be used to remove nutrients and waste from sewage for safer disposal or reuse.

Disinfection

The final stage is removing microbes through the process of disinfection and also the removal of odours from the wastewater.

This disinfection stage can include the use of :

  • Ozone
  • Ultraviolet (UV) light
  • Chlorine Dioxide

Chlorine Dioxide is particularly effective at removing micro-organisms in treated wastewate. These include bacteria, viruses and parasites such as Giardia and Cryptosporidium.

"ClO2 acts differently to chlorine disinfectant – it is a pure oxidant. It reacts with odour-causing compounds, breaks down phenols and doesn’t produce THMs. Modern Catalytic Chlorine Dioxide Generators (ClO2IX) are able to produce reliable, high purity water, with no taste, colour or residue, that can be recycled and re-used across multiple cycles."

Once the wastewater is disinfected it can be used again in a variety of agricultural and industrial applications.

There are obviously strict environmental regulations around the safe disposal and reuse of water and sludge in agriculture and industry. You can read more about your legal responsibilities here.

And don’t forget, a regular regime of testing is very important to ensure that the water you’re disposing of (or reusing) is safe and within allowable limits for microbiological growth.

Reduce your water intake costs - and 'make something on the side'

But being able to efficiently recycle wastewater is not only about your green responsibilities, it can save you significant amounts of money by reducing your required intake of freshwater, too.

What’s more, the treated industrial sludge that is the byproduct of this entire process can be used as fertiliser or in a number of ‘waste to energy’ applications.

"Re-purposing trade effluent instead of discharging it is being made possible by a whole range of ‘sludge to energy’ technology and heat recovery systems. Output can be sold on to third parties or used internally to help waste disposal operations become cost neutral."

The circular economy is a hot topic right now - and water treatment is a significant opportunity for ambitious companies who want to realise the benefit of smarter water management in a highly sustainable way.

WCS Group’s Wastewater and Dewatering team provides specialist commercial and industrial water treatment knowledge which enables wastewater to be re-used, therefore reducing discharge. To find out more about how our solutions could help you, click here.

Want to know more about the world of water treatment and reuse?

Brush up your jargon with this glossary of wastewater terms:

Aeration Tank

The biological treatment of wastewater takes place in the aeration tank.

Ammonical Nitrate

Is a toxic pollutant often found in landfill leachate and in waste products, such as sewage

Black Water

Blackwater is waste water that contains biological material such as grease or faeces.

Biochemical Oxygen Demand

Biochemical oxygen demand (BOD) is the amount of dissolved oxygen needed by aerobic biological organisms to break down organic material

Chemical Oxygen Demand

This is another measure of waste water quality. COD is a measurement of the oxygen required to oxidize soluble and particulate organic matter in water

Discharge Licence or Consents

The permissions you need from your provider to discharge commercial or industrial waste into a public sewer. The cost of doing this will vary according to the quality and quantity of the waste you are disposing of. Trade effluent consents normally require equipment to be installed that will measure the flow.

Grease trap

A machine designed to intercept or "trap" fats, oils and grease (FOG) while allowing clear water to escape into the drains.

Grey Water

Wastewater generated in households or businesses from streams without fecal contamination, sinks, showers, washing machines, dishwashers.

Pathogen

A pathogen or infectious agent is a biological agent that causes disease or illness to its host.

Reverse Osmosis

Reverse osmosis is a water purification process that uses a partially permeable membrane to remove ions, unwanted molecules and larger particles from water

Sludge

Sludge is a byproduct of wastewater treatment. It can be digested using bacteria, which can, in turn, be used to generate electricity. Sludge can also be incinerated or condense and reused as fertilizer.

Suspended Solids

Suspended solids are small solid particles which remain in suspension in water.

Turbidity

Turbidity is the cloudiness or haziness of a fluid typically invisible to the naked eye

Water Treatment

Topics: Wastewater, Water Testing, water reuse

James Greenwood

Written by James Greenwood

James Greenwood as been working in the Water Treatment and Water Hygiene Industry for over 20 years. He is currently the Sales and Marketing Director for WCS Group the largest water hygiene and treatment Company in the UK. James has been instrumental in bringing significant innovations to the UK market over the years always focusing on enhancing client’s compliance and delivering true return on investment projects offering monetary and environmental savings.