Water Treatment - Why & How?
When we receive a brief to deliver a water treatment system, there are many questions to be asked before we can design the best possible solution for the project. What do we need to do with the water? What are the flow rates of the water to be treated? Plus what contaminants are in the water... and to what level do they need to be reduced for either safe discharge or for the water to be recycled?
Once we've determined these factors, our team of engineers will select from a wide range of technologies to develop the ideal solution for the site specific needs. We'll look at the various water treatment technologies available, but first let's look at the main contaminants found in waste water and why these contaminants needs to be treated (or reduced) from a waste water stream prior to discharge or before the water is suitable to be recycled and used for another purpose:
|
Contaminant |
Reason for removal from water |
|
Suspended solids |
Can lead to the development of sludge deposits and anaerobic conditions when untreated wastewater is discharged in the aquatic environment. |
|
Biodegradable organics |
Composed mostly of proteins, carbohydrates and fats biodegradable organics are measured most commonly in terms of BOD (biochemical oxygen demand) and COD (chemical oxygen demand). If discharged untreated to the environment, their biological stabilisation can lead to the depletion of natural oxygen in the water and to the development of septic conditions. |
|
Pathogens |
Communicable diseases can be transmitted by the pathogenic organisms that may be present in wastewater. |
|
Nutrients |
Both nitrogen and phosphorus, along with carbon, are essential nutrients for growth. When discharged to the aquatic environment, these nutrients can lead to the growth of undesirable aquatic life. When discharged in excessive amounts on land, they can also lead to the pollution of groundwater. |
|
Priority pollutants |
Organic and inorganic compounds selected on the basis of their known or suspected high risk to human health. Many of these compounds are found in wastewater. |
|
Refractory organics |
These organics tend to resist conventional methods of wastewater treatment. Typical examples including surfactants, phenols, and agricultural pesticides. |
|
Heavy metals |
Usually added to wastewater from commercial or industrial activities and may have to be removed if the wastewater is to be reused. |
|
Dissolved inorganics |
Inorganic contaminants such as calcium, sodium and sulphate are added to the original domestic water supply as a result of water use in industrial processes and may have to be removed if the wastewater is to be reused. |
Now that we've developed an understanding of “why” water needs to be treated, we can move on to understand “how” we treat it. The following table provides seven different levels of treatment along with the appropriate system available from Clearmake to achieve the required level of contaminant removal:
|
Treatment Level |
Description |
Equivalent Clearmake Product |
|
Pre Treatment / Primary Treatment |
Removal of gross wastewater contaminants such as rags, sticks, floatables, grit and grease that may cause maintenance or operational problems with downstream treatment operations, processes, and ancillary systems. |
Gross pollutant trap Oil/Water Separator
|
|
Advanced Primary |
Enhanced removal of suspended solids and heavy metals from the wastewater. Typically, accomplished by chemical dosing and filtration. |
Screening + WTS + Filtration GWTS |
|
Advanced Primary plus Disinfection |
Enhanced removal of suspended solids and heavy metals to produce water of clarity sufficient for effective disinfection. |
WRS |
|
Secondary (Trace Organics) |
Removal of residual suspended solids and trace organics by granular activated carbon filtration. Disinfection is also included for recycling applications. |
WRS + Granular Activated Carbon (GAC) |
|
Secondary (Gross Organics) |
Removal of suspended solids and dissolved biodegradable organic matter. Disinfection is also included for recycling applications. |
WTS / WRS + Aerobic Biological Treatment |
|
Tertiary (Potable water) |
Removal of super-fine suspended materials remaining after normal biological treatment when required for various water reuse applications. |
WRS + Aerobic Biological Treatment + Micro-filtration, or Ultra-filtration |
|
Advanced Tertiary (Potable water) |
Removal of dissolved inorganics and super-fine suspended materials remaining after normal biological treatment when required for various water reuse applications. |
WRS + Aerobic Biological Treatment + Micro-filtration, or Ultra-filtration + Reverse Osmosis |
WTS - Water Treatment System
WRS - Water Recycling System
GWTS - Ground Water Treatment System
There are a few regulatory requirements you should be aware of prior to finalising your next water treatment project:
- EPA requirements for discharge
- DERM (EPA equivalent for Qld) requirements for discharge
- Council requirements – these will vary across council regions
- Sewer volume and discharge contamination limits
- Storm water discharge contamination limits
Of course when you select to work with Clearmake, we'll guide you through this process and ensure the water treatment system designed for you, meets all regulatory requirements. So if you'd like a quote on a water treatment solution for your business, contact Clearmake today.
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