Category: Water Treatment Technologies

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.

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Get in Touch with AllWater Technologies

We’re here to help with all your water treatment needs. Whether you have questions about our services, want to discuss a project, or need support, our team is ready to assist you. Fill out the form for general enquiries, or you are welcome to email direct or give us a call.

AllWater House

Unit 2,

Cheddar Business Park,

Wedmore Road,

Cheddar

BS27 3EB

Opening hours

Mon-Fri: 08:30-17:30 (GMT)

Immediate assistance

+44 (0) 1934 751333
enquiries@allwatertech.co.uk


    Our Technologies for Removing Contaminants from Water

    The ongoing problem of how to deal with wastewater from industrial practices is a modern, man-made problem that requires complex and wide-ranging solutions.

    At AllWater Technologies, that’s exactly what we provide our clients: cost-effective, responsible and sustainable wastewater treatment systems using the latest in technology.

    In Part 1 of our series on wastewater treatment, we covered the most common and problematic contaminants that we remove for our clients across a range of manufacturing industries. Here, in Part 2, we delve into the kinds of technology we employ in the intelligent solutions we deliver.

    State-of-the-Art Bespoke Solutions

    From the smallest job to the largest and most complex industrial water treatment system, AllWater’s more than fifty years of experience allows us to identify exactly what our clients need. We work closely with them at every stage to ensure that the solutions we provide are not only the most effective, but also the most appropriate for them in terms of budget, operational requirements, flexibility and compliance. 

    With many years of expertise, we utilise a broad spectrum of state-of-the-art technology and equipment to remove the vast range of chemical contaminants produced as industrial waste. Below we detail the most effective and sustainable solutions we use for our clients. 

    Chemical Reaction Vessel

    Reaction vessels form an integral part of many wastewater treatment systems and we use them in a variety of the processes we employ for our clients, including:
    • Cyanide oxidation
    • Chrome reduction
    • pH correction
    • Precipitation
    • Sulphate removal
    • Phosphate removal
    Over many years designing practical, flexible solutions, our experience has shown us that the most important consideration when installing a suitable reaction tank is ensuring homogeneous reaction conditions are maintained at all times. In order to do this, it is necessary for us to employ the correct method of mixing, which most often is an electrically powered mechanical stirrer. It’s very important that the impellers (the rotating part) on the stirrer provide an adequate level of mixing but without cavitation. In order to assist in this, we may position the stirrer offset to the centre of the tank and, additionally, we may employ baffles as part of the tank itself. Other aspects that we consider on a case-by-case basis for our clients include:
    • Size
    • Construction
    • Flow
    • Positioning
    If a mixer is not adequately sized or the reaction tank design is poor, there is the danger in some instances that solids may build up at the bottom of the reaction tank leading to unnecessary maintenance requirements.

    At AllWater Technologies we always carefully consider the construction materials for the tank and stirrer to ensure they are appropriate for the client. For example, for a reaction tank operating at low pH containing a high level of chlorides or even sulphates, it may be necessary to employ a mixer with a shaft and impeller that are suitably coated to offer chemical resistance.  

    We also consider flow through the tank, to ensure that any reagent dosed adequately contacts the waste being treated. For example, if the waste water inlet and outlet of a reaction tank are both at the top, and mixing is not adequate, then there is danger that any chemicals dosed onto the top of the tank will immediately flow straight out without adequately contacting the waste. To this end, our reaction tanks are often designed so that the waste enters at the top but exits from the bottom. Where we employ a riser tube to assist in this, we ensure that there is no chance of syphoning forward from one tank to another.

    When designing bespoke systems for a client we also very carefully consider the positioning of instruments within a reaction tank. Where the instrument is contacting the waste in order to provide measurement, we make sure it is suitably submersed so that our clients can gain consistent readings. For example, we would never install a pH probe immediately adjacent to an injection of acid or alkaline reagent but within the homogenous body of water. Where any instrument is likely to require regular maintenance either for cleaning or calibration, we give special consideration to ease of access and removal. 

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    When we employ flocculation (the addition of a reagent to aid aggregation of smaller particles in order to assist in their removal) in our clients’ wastewater treatment systems, it is usually carried out in a reaction tank or flocculation chamber. Again, we often use a stirrer to ensure adequate contact of the dosed chemical with the waste water. However, in that instance we take great care to ensure that whilst mixing is vigorous enough to prevent solid settlement within the reaction chamber itself, it is not too vigorous as to provide a shearing force that would break up the flocs themselves. To this end we often employ gearing to ensure that the tips of any impellers operate at very slow speed.   

    When we design a system for a client that requires pumping waste containing solids into a settlement or flotation vessel, in-line flocculation may be employed after the pump, so that any flocs that might be formed are not broken up by passage through the pump. In this instance, we may use an in-line static mixer – which is designed to create a high level of turbulence within the pipe, without being excessive enough to break down any newly formed flocs – to provide the dynamic energy required for homogenous mixing.

    Because AllWater’s clients come from a range of different industries with different needs, we use various types of settlement tanks for the removal of solids that have a tendency to sink rather than float.
    • A ‘Dortmund’ type settler is a vertical cylindrical tank with a conical bottom. Water enters the tank via a stilling area in the centre before passing down and exiting the stilling pipe near the conical bottom of the tank. From here the waste rises back up through the tank at low velocity, before exiting via a peripheral weir at the top. We ensure that the design velocity up through the tank is such that it is lower than the velocity at which solids drop through the water column. Solids then collect in the conical bottom of the tank before removal for further treatment or offsite disposal.
    • Tilted plate or lamellar type settlers employ a series of plates installed at an angle within a tank to increase the projected surface area. Similar to the Dortmund clarifier, water enters near the bottom before passing up through the tilted plate area. Solids falling out of the water column have a relatively short distance to travel before contacting the plates, where they join with other solids before sliding off into the sloping base of the tank. Like the Dortmund clarifiers we use in our wastewater treatment systems, from here the solids can be removed for disposal or further treatment.
    In our systems that use a filter press, sludge from a settlement tank is pumped in under pressure and cloths fitted inside the chambers trap the solids, allowing the filtered waste water to exit the press.
    • The number and size of chambers within a press can vary typically between 10 – 90 chambers, and anywhere from 270ml square plates to upward of 1200ml.
    • The chambers are generally between 25 – 30ml deep, depending upon the nature of the waste to be filtered.
    • The chambers are sealed together by endplates and a hydraulic ram to ensure that water does not seep out between the plates.
    • We can individually port filter press plates, meaning that any filtered water comes out from a particular plate or can be internally ported where the filtrate exits via a number of common ports.
    • Depending upon the nature of the solids and the operating pressure of the press and feed pump, the solid content of the filter cake can vary, but a range of 25% – 35% solids is typical.
    • The cloths are generally constructed from a material such as woven polypropylene and must be regularly cleaned to prevent the weave becoming blocked, which can result in long filtration times and poor filter cake solid content.

    Get in Touch with AllWater Technologies

    We’re here to help with all your water treatment needs. Whether you have questions about our services, want to discuss a project, or need support, our team is ready to assist you. Fill out the form for general enquiries, or you are welcome to email direct or give us a call.

    AllWater House

    Unit 2,

    Cheddar Business Park,

    Wedmore Road,

    Cheddar

    BS27 3EB

    Opening hours

    Mon-Fri: 08:30-17:30 (GMT)

    Immediate assistance

    +44 (0) 1934 751333
    enquiries@allwatertech.co.uk