MILLENNIUM GLOBAL, INC.
Water Purification Processes
Waste Water Treatment – Process Water Treatment &
Potable Water Processes
Millennium Global, Inc. (MGI) specializes in delivering custom solution water purification systems. MGI provides systems that treat a wide range of commercial, municipal and industrial applications. MGI provides turnkey system design, and construction for new grassroots facilities as well as revamps of existing systems with new technologies to improve the overall performance of the water treatment process. Many of these systems are skid mounted for ease of design and installation and can be built modularly and shipped around the world. Larger systems are constructed on site, with as much infrastructure being modular and pre-constructed as possible.
The first part of any project requiring a water purification application is an initial assessment of its environmental impact, public health affects and economic feasibility. This requires an understanding of the overall scope of the project and the source water quality. In most cases the need for an environmental and public health solution supersedes the economic viability of the project, however it is still important to investigate the most cost effective and efficient methods available.
Water Purification Processes
Production of Drinking Water
There are typically three main sources of water in the potable water source of supply, including: sea water, surface water (rivers or lakes) or underground aquifers. There are certain overall project goals that must be considered prior to rejecting or selecting a particular water source. In some locations seawater, ground water and aquifer water may be accessible. It is therefore necessary to match the final water product purity requirements, supply rate and distance the water is to be piped to storage or use points.
When all parameters are considered, seawater is usually the most costly however many topographies do not have a local source of groundwater and the aquifers may not provide the necessary rate of supply to the use points. In this instance the most costly option becomes the only solution. For seawater applications further from the coastline, pipeline installations will add to the cost of the project.
For locations remote from the coastline, aquifer and ground water sources are the most common. The first determination that must be made for aquifer supply is the depth of the well that must be dug. Once this is understood, the overall size and topography of the aquifer must be evaluated to determine the projected life of the water supply before modifications to the well will need to be considered. Finally and critically important is the geometry of the aquifer so that the supply rate can be calculated to determine if it will meet peak demand today and in the future with projected area population growth or use point addition.
Ground water, including river and lake sources is the easiest to incorporate into the potable water supply chain. Rarely is longevity of the supply and the demand rate an issue with these water sources. The challenges here typically are in the purification processes resulting from contaminants in the source. For this reason a thorough understanding of the contaminants, their source and variability is a must in the process design of the water supply system.
(Typical Desalination process)
Purification of Process Wastewater
Industrial processes generate wastewater with a wide range of contaminants that need to be removed prior to returning to the process for further use or prior to being released to sewage or groundwater systems. Typical MGI solution designs treat water from: refining, chemical, mining, semiconductor, food, and other specialty industrial applications.
The following process flow indicates most of the processes required for potable water treatment as well as process wastewater treatment are the same. Process effluent will enter the continuum further downstream from drinking water sources and exit the process upstream of final potable water processing. The processes shown are typical and the following section describes how each are used in the overall treatment scheme.
Settling Process Wastewater
Neutralization / Stabilization
Micro & Ultrafiltration
Storage Return to Process
Fresh Water Supply
Purification Process Technologies
There are a number of purification techniques that are used in the conversion of raw water into purified potable water. Each of these processes has unique characteristics and range of scenarios where they are effective. Most water solution processes will require several of these techniques combined in a custom designed technical solution package for each individual application.
The following list summarizes the most frequently used purification processes. This is not an exhaustive list and the final solution may contain additional methodologies:
1. Desalination - The overall process of purifying seawater into potable water. This process typically includes: course filtration, pre-treatment (pH and alkalinity adjustments), reverse osmosis and post treatment (microfiltration and biocide addition).
2. Course filtration - Bulk solids and debris removal prior to entering any pumping or treatment stations. Typically these are 100 micron filters.
3. Fine filtration - Mechanical filtration used to remove entrained particulates from the raw water stream. Typically these are 5 micron and 1 micron filters.
4. Neutralization - This is a chemical process of pH adjustment to a range of 6.0 to 7.6. This is typically a CSTR (Continuously Stirred Tank Reactor) operation.
5. Stabilization - This process rebalances the alkalinity of the water stream that may have been altered during the initial pretreatment processes.
6. Reverse Osmosis - A special case of diffusion in which the molecules are water and the concentration gradient occurs across a semi permeable membrane. The semi permeable membrane allows the passage of water, but not ions (e.g., Na+, Ca2+, Cl-) or larger molecules (e.g., glucose, urea, bacteria). Reverse Osmosis is a basic technology used in TDS removal that reduces conductivity of the process streams.
7. Biological Treatment – Anoxic and Aerobic systems remove organic Nitrogen containing compounds from water. This is a critical step prior to UV processes to ensure total destruction of bioactive species.
8. Nanofiltration - Nanofiltration membranes have the unique ability to selectively remove problem compounds or ions, while retainingsome hardness which is a desirable property for potable water applications.
9. Ultrafiltration - Size exclusion separation technique that employs hollow membrane technology. The separation of impurities is as small as 0.025 microns.
10. Electrodialysis - Involves the removal of salts by separating and collecting their chemical components through electrolysis. This is generally used for salty groundwater and not seawater.
11. Ion Exchange Resins - Ion exchange resins are polymers that are capable of exchanging particular ions within the polymer with ions in a solution that is passed through them. The aim is usually either to soften the water or to remove the mineral content altogether. The water is softened by using a resin containing Na+ cations but which binds Ca2+ and Mg2+ more strongly than Na+.
12. Carbon Filtration - Activated carbon is useful in drinking water treatment because it acts as an adsorbent, and can effectively remove particles and organics from water.
13. Chelating Process - In this process a chelating agent such as supercritical carbon dioxide, Ethylene Diamine Tetracetic Acid (EDTA) and other organic compounds are contacted with the water stream. The metal reacts with the chelating agent to form a metal chelate which transfers into a supercritical or flocculated state that can be mechanically removed.
14. Ozone - Ozone is an unstable gas comprising of three oxygen atoms, the gas will readily degrade back to oxygen, and during this transition a free oxygen atom, or free radical is form. The free oxygen radical is highly reactive and short lived and has a strong destruction affinity for iron, sulfur, viruses, bacteria, transition metals and cyanic (cyanide) compounds.
15. Ultraviolet Light - Ultraviolet (UV) disinfection uses a UV light source, which is enclosed in a transparent protective sleeve. Water passes through a flow chamber, and UV rays are admitted and absorbed into the stream. When ultraviolet energy is absorbed by the viral and bacterial organisms, they are destroyed.
1. Ozone treatment for Cyanide removal:
(Ozone Generators - North Carolina)
p Bulk removal with OZONE (O3)
CN– + O3 ? CNO– + O2
2 CNO – + 3O3 + H2O ? 2 HCO – 3 + N2 + 3O2
p Ion Exchange
p Complex cyanate removal
p Ultraviolet Light (UV) Destruction
p Destruction of residual byproducts
p Reverse Osmosis
p Metal complex removal
2. Plant wastewater – Reverse Osmosis for TSS/TDS removal for Conductivity reduction
(Neutralization / Stabilization Processes) (Reverse Osmosis Membranes)
(Chemical feed agent storage tanks) (Pre-filtration for TDS and TSS removal)
3. Specialty Gas water and air treatment system
(Contacting towers – halide removal) (Caustic feed tanks) (Tank Installation)
(Emergency exhaust treatment – Metal halides, organic vapors) (Poly Tank Installation)