Monday, April 23, 2012

Improving Efficiency of Water Softeners at a Hospital

A customer found they could reduce the salt and water costs of regeneration by 63% by having our service person diagnose the problems they were having and make changes to the system.

Situation:A hospital customer has a 20 cubic foot water softener used for domestic water.  The system was designed for run length of of 20,000 gallons between regenerations, but recent records indicate the run length has reduced to 10,000 gallons.  The hospital demand is approximately 10,000 gallons per day.  The following is the cost information:
  • Water and Sewer Cost - $4.00/1000 gallons
  • Salt Cost - $0.05/lb
After inspection of the unit and analysis of resin samples, several problems were found:
  • The softener had 7 cu ft missing in the softener
  • The resin was fouled with iron
  • The regeneration cycle needed to be adjusted
The following changes were made:
  • 7 cubic feet of cation softening resin was added to the softener
  • The resin was cleaned to remove iron and a preventative maintenance program will maintain clean resin in the future
  • The regeneration cycle was changed to the design conditions
The following are the benefits the customer realized by making the recommended changes:
  • The number of regenerations dropped from 365 to 182 per year
  • The salt use per regeneration dropped from 180 lbs to 120 lbs.
  • The water use pre-regeneration decreased from 2590 gallons to 2090 gallons
Salt Before
(180lb/regeneration)($0.05/lb)(365 regenerations per year)
Salt After
(120lb/regeneration)($0.05/lb)(182 regenerations per year)
Salt Savings
Water Before
(2590 gallons/regeneration)($4.00/1000 gallons)(365 regenerations per year)
Water After
(2090 gallons/regeneration)($4.00/1000 gallons)(182 regenerations per year)
Water Savings
Total Savings

Monday, April 16, 2012

Water Reuse From Wastewater Using RO

Often we are asked to help with water re-use project.  From their research, prospective customers are often interested in using an RO system.  They want to take advantage of the key features which make RO a great technology for treating water entering their plant for process applications:
  • The RO membrane is barrier between the treated and untreated water
  • Reverse osmosis reduces the TDS (Total Dissolved Solids)
  • RO systems and membranes are a robust, proven technology
These advantages have been quantified and defined when an RO system is desalinating water and treating municipal/well water.  More information is required before any RO is placed on a process waste stream.  Often a pilot is required.  Our parent company, Ecolab, has extensive experience with water treatment and reuse applications, but more information than a standard water test is needed to determine whether RO has a chance of working.

When looking at a water re-use project from wastewater, regardless of where the water re-use potential location is, it is essential that the water quality is considered both from a physical /chemical perspective but also from a biological perspective. What that means is analysis for parameters such as BOD / COD,( Biological Oxygen Demand / Chemical Oxygen Demand), turbidity , FOG ( Fats, Oils & Grease), NH3 /TKN ,( ammonia /total Kjeldahl nitrogen), NO3 and Total P as well as TSS ( Total Suspended Solids ) and conductivity or TDS( Total Dissolved Solids) should be added to the more typical water analysis list.  If your facility is a food and beverage plant, a microbiological assay should be done.

NOTE- most of these tests require special sampling methods and handling.  The WHO (World Health Organization) has an excellent paper on the subject "Water Quality Monitoring - A Practical Guide to the Design and Implementation of Freshwater Quality Studies and Monitoring Programmes".  Look at pages 17-18.

Additional Information:
Definition of Waste water quality parameters
The Kjeldahl test method used to determine the nitrogen concentration in a waste stream
Standard Methods For the Examination Of Water and Wastewater

Tuesday, April 03, 2012

Chloramine Removal With Catalytic Carbon

Is your carbon under attack? Have you chosen the correct carbon for chloramine removal? What carbon makes the most effective final barrier against chloramines?

Why use chloramination?Let's face it everyone, they're not making any more fresh water on this planet. Our fresh water is under continuous attack from man made substances and biological bad guys. To combat these contaminates, our municipalities are continually challenged to find the "right" treatment. For instance, good old chlorine was effective to combat bacteria and most disease. However, as our water systems with miles of pipe kept growing, chlorine's "staying power" was found to be less effective at the end of the line. And worse yet, chlorine would complex with organic matter (pipe sludge) or natural algae, to create disinfection by-products (THM's). Enter Chloramine. Some science guru dreamt up the idea that chlorine was more effective if they mixed in some Ammonia. Yes, ammonia. Chlorine+Ammonia = Chloramine

As you might imagine, chloramine wasn't the magic bullet bio fighting miracle. Needless to say, Chloramine, is better off in the street pipes than in you or in your ingredients. Ok? Now what? Since the invention of chlorine, man used activated carbon as the final barrier to remove it. Most activated carbon is manufactured from coal or coconut shells. Chloramine removal turned out to be a much trickier challenge. Here's why: Most drinking water is at pH 7 or above. At pH 7 chloramine forms into a monochloramine. Monochloramines are highly stable by nature making them very difficult to remove with traditional activated carbons. Calgon discovered if you manufacture carbon with catalytic functionality, it will remove the chloramine. Here's how: traditional carbon would do an excellent job of removing the chlorine portion, but leave a significant amount of ammonia. Catalytic enhancements to traditional carbon allowed the carbon to retain more oxygen. The oxygen acted as the needed catalyst to breakdown the ammonia. Simple 'eh?

Coconut vs Coal based carbon
YES you have a choice. This is America. It comes down to this: Our real world results have confirmed the coconut shell based catalytic carbons the clear winner.

A comparison between coconut and coal chloramine made by Jacobi CZ-MCA Technical Paper
Coconut vs Coal Chloramine Removal Comparison
from Jacobi CX-MCA Technical Paper
 I speculate that coconut shell carbons have a micro-pure structure that allows them to retain more oxygen, thus be more catalytic. Also, scientific proof tells us that the coconut shell carbon is physically harder than coal carbons. When dechlorinating, carbon gives up a structural molecule. Coconut shell's strength gives it an advantage in the long run.

For Additional Information:
If you are really into the technical wizardry, read what the really smart folks wrote:
Technical Bulletin for Jacobi Aquasorb CX-MCA Catalytic Coconut Carbon
Technical Paper "Treatment for Monochloramine Using Activated Carbon" by Jacobi Carbon