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Situations where Water Purification is needed

We subdivide situations of emergencies into scenarios and setting. The main scenarios for humanitarian help are presented as Fig 3. showing specific situations either in terms of climate or living conditions of the population, which can be the case for different scenarios (see Fig. 4).

                                                                                                                         

Fig. 3: Emergency scenarios where humanitarian actions have been implemented and water and sanitation always played an important role.

Fig. 4:  Emergency setting that can be situations under all the different scenarios and also pose different requirements to equipment and type of installations.

 

Raw Water Quality

 

Typically in emergency situations requiring the actions of humanitarian organizations, the raw water quality is mainly the result of the natural environment. This means that pollutants of industry and huge conglomerations can be excluded, unfortunately, this is not fully correct, because during the last years emergencies in huge cities and industrialized areas have become a more serious problem. However, for this overview, natural environments are taken as the basis.

 

Raw water in natural environments has mainly three characteristics, which are important for purification:

 

1. High turbidity (both inorganic and organic components)

2. Potentially high salinity

3. Load of specific natural pollutants such as arsenic, heavy metals, fluoride

 

For most treatment processes, high turbidity is a severe problem. In order for all proper treatment processes, the water has to be made clear before other organic and pathogen pollutants can be removed. So, filtration of different types is always the critical process in water treatment.

 

Raw water in tropical rivers can reach turbidity on the NTU scale of more than 1000. This means that visibility through the water is less than 1 cm. Visibility through a water column (measure of NTU) has to be at least at 40 cm, before treatment can properly be applied.

 

In the case of high salinity, there are only very limited processes that can be applied to produce water of good quality. Osmosis and reverse osmosis are processes which cover this spectrum; with the general benefit being that a large majority of other mineral and pollutants are removed during the same process.  Also distillation with different technologies has provided good results when applied to saline water.

 

There are many areas in emergency prone regions, where natural water has a high content of arsenic, fluoride and other heavy metals.

There are processes to remove these components, however, in emergency settings; such water sources will usually be omitted.

 

Use of Purified Water in Emergency Situations.

Focusing on emergency situations and emergency operations, water is the priority necessity for human beings, both for the staff and personnel giving support and the suffering population. Usually, animals and agricultural use is excluded in a first phase of an emergency operation.

 

The demand of a human being consists of water for drinking, cleaning, washing and cooking. Usually, in an emergency situation only one type of water is focused on, this being water of drinking water quality. In extreme situations, however, solutions have to be chosen where drinking water and washing water are distributed separately.

 

In several situations, solutions have to be such where drinking water (highly limited quantities) is distributed separately from larger amounts of washing water.

 

However, such situations require the training and education of staff and people, to provide proper monitoring and supervision, and often a double capacity of equipment for distribution (i.e. tanks, tap stands, distribution pipes, etc.).

 

Water Purification Units and Treatment Solutions.

The next step would be to look into existing technologies and water purification units already in use in the work of humanitarian organizations.

 

The different approaches can mainly be divided into technologies using chlorination as a disinfection process and those using other solutions, such as UV -lamps, ozone, and ion exchange based techniques. There are also filter technologies which removes bacteria, in this report called "micro-filters", which mainly consist of membranes with pore sizes smaller then pathogenic bacteria (< 0.04 microns).

 

Most technologies use several different processes to reach a satisfactory solution for different qualities of raw-water.

 

Most processes need a filtration of the raw-water to remove inorganic and organic suspensions in the water.

 

Some filtration technologies, especially those applying micro-filters, also remove pathogenic organisms in addition to heavy metals or pesticides.

However, this is dependent upon other components being present in the raw-water, due to their ability to connect to particles in organic or inorganic suspensions.

 

Fig. 5:  The most common water purification processes plotted in a quality vs. quantity diagram.

 

The processes mentioned above (see Fig. 5) cover the range of subjects, which has to be in focus for humanitarian aid work both in emergencies and development. The critical part is always the filtration, because the raw-water is usually heavily loaded with suspension of both inorganic and organic material.

As long as the turbidity as a measure for suspension is above 15 NTU, filtration processes will slow down very easily and micro-filtration will not possible due to clogging of any filter surface (filter membranes, ceramics, etc.).

Sand-filters as a more 3-dimensional filter medium have a much greater potential to handle high-turbidity water. Also back-washing of sand-filters is more effective than back washing of membrane filters.

Disinfection, meaning guaranteed removal of any pathogenic organisms, is usually a process only working with "clear" (<15 NTU) water. Chlorination, micro-filtration, UV lamps, ion- exchanger, oxidation, etc. are those most commonly used processes to achieve proper and safe drinking water.

 

So, in conclusion so far, it has to be mentioned that focus for any type of water purification system should be on treating highly turbid raw-water combined with a proper technology for disinfection.

Our MEL Unit models has been engineered and manufactured with 3 main processes of purification:

1)             Activated Carbon Filters

2)             Reverse Osmosis Membranes

3)             Ultraviolet Sterilizers

Thus, the MEL Unit provides top quality drinking water production.

Main Characteristics and Advantages of the MEL Unit.

 

As described on technical data sheet rev.1 dated 25.09.2003, the MEL unit can provide the following remarkable advantages:

 

·  High protection because all equipment are installed into a steel container.

·  Working time, maintenance, etc.., are under the full control of the design operator that handles the keys of the container.

·  The equipment and instruments are of high quality and advanced technology but not so sophisticated as to produce operations or maintenance problems or require replacement of spare parts.

·  Low costs of operation.

·  No use of chemical products (chlorine, Al sulphates, etc..).

·  High confidence of the processes used.

·  Only routine maintenance required.

·  Total removal / destruction of organic substances.

·  Total removal / destruction of micro-organisms.

 

Each Unit is tested by our Quality Control department and certified by "Third Party Inspection" at our workshop before issue the "Release Note" that authorizes the delivery to the Client.

 

Practical Installation and Use of MEL Unit.

·  MEL 4.000 Unit Installation.

 

The Local Water Authority would establish the location for the installation of the Unit. Operators will carefully unload the unit from the truck and place it in a

"lay-down" position  on a level surface.

As the container is laid on the proper place, the operators would then:

-   Open the door of the container.

-   Check that all the equipments inside is not damaged.

-   Certify by packing list all parts are accounted for.

-   Arrange all the devices and equipments necessary to connect the Unit to the water source.

-   Provide the hoses, pipes, distributors, taps for the distribution of drinking water.

-   Check the generator connection.

-   Fill the fuel tank.

 

·  START-UP of the Unit

Operator will be provided with:

 

-                               Check list before start-up

-                               Step by step operations for the start-up

Operator is responsible for:

 

-                               Control of the pressure at various stages of the processes

-                               Control of leaks in piping ( if any occur)

-                               Controlling the quality of treated water

-                               Filling the potable water tank inside the container

-                                 As soon as the holding tank is filled at 50%, the discharge valve will be opened and water will be released  to the distributors

-                               Closing of container door and all operations which can be handled from outside by the control panel.

 

MAINTENANCE_SCHEDULE Maintenance Replacement
·  Power Generator
1000 h

-

·  Fuel Tank
1 year
-
·  Control Panel
1 year
-
·  Activated Carbon Filters
3-4 months
1 year
·  High pressure Pump
monthly visual
-
· Reverse_Osmosis_Membranes
3-4 months
2 years
·  Ultraviolet Sterilizer
monthly visual
2 years
·  Drinkable Water Tank
1 year
-
·  Distributors with taps
daily visual
-
·  Suction Piping
daily visual
-
·  Process Piping
monthly visual
-
·  Process Instruments
monthly visual
-

 

 

Appendices.

 

References:

·        The SPHERES Project 1998/2001: Humanitarian Charter and Minimum Standard in Disaster Response.

·        Davis, J. & Lambert, R. 1999 (and new edition 2002) : Engineering in Emergencies. A practical Guide for Relief Workers. IT Publication. 103-1105 Southhampton Row, London WC1B4HH, UT.

·        UNHCR: Water Manual for Refugee Situations. Program and Technical Support Section, Geneva, November 1992

·        Drinkable Water - The Life - Usotel edition 1998

 

 

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