More Technologies for Removing Contaminants from Water

In this series, we have surveyed the contaminants that our leading experts in industrial wastewater treatment most frequently encounter (see Part 1), and we have explored some of the industry-leading solutions that we offer to our clients.

There are many solutions available to us, and in Part 2 we looked at some of the most common and effective. Our engineers are experienced in identifying the best techniques for each individual client, taking into account the type of waste, local legal requirements, budget and space constraints and opportunities for optimising the plant’s efficiency. 

In this article, the focus widens to include a raft of other industrial wastewater treatment options that can be tailored to suit your unique business needs.

Multi-Media Filtration

AllWater employs cutting-edge technology in all our wastewater treatment solutions. Historically, sand filters were used to provide an additional level of filtration, often post settlement or dissolved air flotation prior to discharge to drain. However, our state-of-the-art systems now often use anthracite to form a layer above the sand, which offers greater solid retaining capacity. The media is normally contained within a pressurised vessel, which we can automatically backwash to carry away trapped solids. 

Carbon Filtration

This system is similar in design to multi-media filters, but the filters contain granular activated carbon for removal of organics. Various different types of activated carbon are available, including bone charcoal, coconut and coal based. Each offers different properties for use in different applications. For example, coal based carbons have a more open pore structure than coconut based carbons, and are therefore more suitable for removal of synthetic oils. 

Dissolved Air Flotation

Many of our clients are from industries that produce waste containing high levels of oils, fats and greases, which have a tendency to float rather than sink. In these instances we will employ a dissolved air flotation system to create a ‘float’, which rises to the surface of the waste water within the dissolved air flotation chamber and can be removed by a skimmer. 

(Dissolved air refers to the air which is typically introduced to a portion of the clarified effluent under pressure, then released into the incoming waste stream. The release in pressure causes microbubbles to form within flocs as they are produced.)

Organic Adsorbent Dosing

Granular activated carbon (GAC) is an organic adsorbent but in instances where TOC/ COD levels are high, resulting in the need for changing filter media too frequently, dosing of an organic adsorbent may prove a better solution. Activated carbon in powdered form (PAC), made into a slurry and dosed via a ring main can be effective at reducing TOC / COD. The exhausted PAC is subsequently removed along with other solid contaminants following flocculation and settlement. 

An alternative which may offer sufficient removal of organics is Bentonite which is available in Sodium and Calcium forms. It is utilised in a similar manner as PAC in that it is generally made into a slurry and then dosed via a ring main, prior to removal post flocculation and settlement. In some instances a combination of PAC and Bentonite may be used. Bentonite has the added benefit of being a good filtration aid, assisting in dewatering through a filter press. 

Ion Exchange

For our clients who produce heavy metals, we may employ the use of ion exchange resins to remove contaminants down to part per billion levels. We may also use them to provide first stage concentration of contamination. 


Electro-Winning

You might be familiar with this process in the context of the recovery of precious metals. We’ve noticed that this technology has fallen out of favour in recent years, with ion exchange now more commonly used. Typically employed on a recirculating loop from a static dragout post plating bath, metals present are plated out on the cathode and can then theoretically be reused as anode material or most likely sent away for recovery. 

Our wastewater treatment experts will consider this process in those cases where cyanide is one of the contaminants. The oxidative process within the cell will eliminate the cyanide, although it is important to understand that the efficiency of metal removal is greatly affected at lower metal concentrations. The more modern cells that we install have utilised reticulated cathodes in order to help offset this. 

Reverse Osmosis 

For some clients’ wastewater treatment systems we may use RO membranes to provide concentration of contaminants prior to further treatment or offsite disposal of effluent.

Evaporation

Where first stage concentration has taken place, for example, by ion exchange or RO as above, we may use evaporation to reduce volume further prior to disposal if appropriate for our clients  – or in some cases to the point of crystallisation. 

We use various types of evaporator, depending upon a client’s requirements. These offer differing levels of economy when considering both capex and opex. 

  • As the cheapest form of evaporation we recommend, the tank is fitted with a heater and an extraction system. 
  • A falling film evaporator can be more cost effective for our clients from an opex point of view.
  • Vacuum evaporation (where a small vacuum is typically applied to a ‘kettle’) enables liquids to be evaporated at lower boiling points.   

Ultrafiltration (UF)

At AllWater, we’ve got over 50 years of experience in wastewater treatment, and over the past few decades we’ve seen significant advances in the ultrafiltration membranes we use, including type and material of construction. We ensure the UF membrane systems we employ are specific to our individual clients, which is dependent upon the application and the chemical makeup of their effluent. Our UF membranes systems are available as:

  • Spiral wound
  • Hollow fibre
  • Tubular
  • Flat sheet

Applications for our clients vary dramatically and include:

  • Simple removal of inert solids 
  • Removal of bacteria and the residual components of bacterial breakdown
  • Oily water separation


At AllWater, we recognize the importance of creating customised, compliant, and sustainable wastewater systems suited to each unique business. Our extensive expertise in industrial effluent management enables us to provide tailored, economical, and comprehensive systems to clients from various sectors.

If you’re considering upgrading your current facility or installing a new effluent system, we possess the skills, knowledge, and expertise to design and execute a cutting-edge solution. We offer round-the-clock phone support and a dedicated support team, with engineers available nationwide and emergency equipment on hand. Contact one of our highly skilled engineers to discuss your requirements.