Water Treatment Products
Water treatment is such an essential process that affects all kinds of demographics. Therefore, with water being such a large industry it means it is important that the treatment process is made as efficient as possible.
DCM processes focuses on supplying system measurement and analysis that assesses characterisation data to provide information based around various parameters such as DOC, suspended solids and colour that may be present in your various water applications (bores, rivers, reservoirs etc). The information we obtain can be beneficial as it shows:
What is present in your specific water sample
Any significant or unwanted losses
What dosage is appropriate
Any areas for improvement in the treatment process
We can provide the instruments, installation, maintenance and online monitoring systems that are required in this process, along with extensive knowledge and experience that has been gained from many years of working in the business.
Dissolved Organic Carbon (DOC)
DOC is the Dissolved Organic Carbon level in a sample of water and is usually given in mg/l. A UV-VIS spectrometer can provide a surrogate reading of the DOC using correlations between spectral factors and the laboratory DOC. Calibrations for DOC are specific for different water types as each major water type contains different fundamental compound groups. As with many standard methods parameters its use depends on the application and often more useful information can be provided by UV-VIS system. Since the UV/Vis spectrum is the sum of the absorptions of the different dissolved compounds, detail on the concentration of different groups of organic compounds is usually available in addition to the DOC equivalent.
DCM specialises in providing such breakdowns and this is the basis for much of the work done and capability available in automated source selection, cost to treat management, automated predictive coagulation control (compass), DBP prediction and measurement, chlorine demand and biofilm growth areas.
Specific UV absorbance at 254 nm (SAC254) is a recognised surrogate for organics content in water.
It is often included in compliance criteria for many environmental applications.
UV-VIS spectrometers measure the entire spectrum between 190nm and 740nm also 254 nm.
It needs to be noted A254 as a lab standard method involves the pre-treatment of the water by filtering using a 0.45-µm filter. The assumption is that the remaining absorbance is due to soluble material. This is often not the case as fine colloidal material tends to pass through such a lab filter. Some examples where this can be problematic are:
Treated municipal wastewater
Treated and untreated industrial wastewater
Environmental waters such as the Murray River and others containing colloidal clays etc.
If mathematically compensation for solids is provided the presence of these particulates will therefore give a lower A254 than the lab when the lab measurement is being interfered with by colloidal material. Verification of this can be achieved by simply refiltering the 0.45 micron filtrate with a 0.22 micron filter after checking the A254.
The A254 is often used as a surrogate for determining TOC or DOC in a water sample due to the complexity and cost of DOC/TOC testing. The lab test for these involves sample oxidation by chemical or heat to form Carbon Dioxide (CO2) which is then measured with a UV detection system. It needs to be noted that the A254 will provide good correlations to DOC/TOC while the composition of the water is relatively stable however this relationship will normally break down during times of compositional change which is often when the reading is needed most.
DCM can provide the equipment to not only provide you with raw and filtered 254 values plus transmissivity, the systems can tell you when the composition is changing and you need to recheck your 254 to DOC correlations.
Total Organic Carbon (TOC)
UV-VIS spectrometer determine TOC by measuring the absorptions caused by organic compounds in the UV/VIS spectrum and mathematically links them to the lab TOC.
Toxicity in water is a complex issue. Interpretations of what is meant by toxicity are wide and generally application / industry specific. DCM has extensive experience in this area and by using UV-VIS spectrometer and other sensors can analyse your water samples and then advise the best pathway to achieve a suitable outcome for your application.
Turbidity & Suspended Solids
Different Turbidity and Suspended Solids sensors using different technics are available.
A UV-VIS spectrometer also provides chemical free measurement of not only nitrate but COD, Solids and more. Designed to operate in high solids settling applications it is ideal for control of carbon dosing for nitrate reduction or aeration set point control in STPs.
Effective disinfection relies on maintaining disinfectant residuals at levels which will inhibit or kill biofilms. To achieve suitable residuals in distribution systems with varying treated water qualities and retention times is not an easy task.
DCM can now simplify this task by proving continuous chlorine dosing set point adjustment. A UV-VIS spectrometer in conjunction with DCM developed algorithms allows measurement of the levels of organics proven to react with chlorine and thereby remove it from the water. Note this does not take into consideration the effects of removals by biofilms specific to a given distributor however it removes the variability inherent with water quality changes in the clear water leaving the WTP.
Coagulation Control (Compass)
Raw water from a forest covered catchment is likely to have a high concentration of aquatic fulvic and humic acids caused by decaying leaf matter. The fulvic and humic acids present will strongly influence coagulant demand and therefore coagulant dose.
Compass is an advanced coagulant control system, suitable for use with any metal based coagulant. It uses the online measurements of inlet water turbidity and UV-VIS spectral analysis provided by a UV-VIS spectrometer to predict the coagulant dose required to achieve treatment aims.
Compass can be set by the user to operate in either conventional coagulation mode which will achieve particulate removal targets in the most economic manner, or in enhanced coagulation mode which will provide the maximum removal of natural organic matter.
Compass runs within a UV-VIS unit, which generates an output of the required coagulant dose for input in to the plant control system. An external solution is also available. This form of process control is referred to as “Feed Forward” or “predictive” control. It is a proactive means of process control since the plant is being told how to operate based on a measurement of inlet conditions. Feed forward control offers many advantages over the more traditional manual and “Feedback” control method, which is reactive.
Colour and true colour is defined in a number of ways using different Visible and in fact UV wavelengths after defined pre-treatments. UV-VIS spectrometers can provide equavalents for these colour parameters using default and custom software set ups.
Often colour is used as a surrogate for other factors such as treatability of water and confusion often occurs between actual chromatic colour and laboratory “True colour”. The lab colour may contain a substantial amount of light scattering colloidal material which can be mistakenly assumed to be chromatic. DCM can separate these effects which allows effective process control to occur to lower or manage True Colour, chromatic colour and colloidal material.
Disinfection Byproduct (DBP)
Detection and Quantification
Disinfection Byproducts caused by interactions of primarily halogens like bromine and chlorine (plus chloramine in chloraminated systems) with organic compounds in drinking water can be problematic. Laboratory testing is expensive and difficult to interpret in many cases due to the changing drivers for DBP formation.
DCM has completed extensive research with recognised experts in this field to verify the ability of DCM algorithms in conjunction with UV-VIS spectrometer and additional sensors to detect and quantify the organic precursors for DBP formation. This means DCM can indicate based on the data the potential to form DPB’s in a source water allowing you to add this criteria to automated source water selection criteria in addition to cost to treat. Additional measurement at the point of disinfection and in the distribution system itself allows direct quantification of the THM and HAA levels occurring in real time.