The potential impact of an efficient RO Plant
Tackling the disparity of access to clean water
“Accelerating change to solve the water and sanitation crisis”- the theme for this year’s World Water Day.
For many of us, we don’t think twice about the fact that water flows freely each time we turn on the faucet. This, however, is not the case for all. In fact, throughout the world today billions of people still do not have access to clean water and sanitation facilities.
Given the extent of this disparity, we are often left in a tailspin at where to begin to solve this problem; but this only feeds the crisis and risk posed to our water cycle at large.
So where do we begin…
Aptly adopted as part of this year’s World Water Day theme, the story of the hummingbird accurately illustrates the power of collective effort.
With one drop at a time, she chooses to take ownership of her share of the responsibility and plays her part – with what she can.
The onus is on both individuals and industry to do better
Playing our part
At UDEC, we consider it our purpose to encourage efficient processing of our planet’s natural resources.
We therefore began investigating the potential impact that a collective effort can make. What could we actually achieve together if everyone adopted an attitude such as that of the hummingbird?
“What if with more efficient RO practices, we could save enough energy to power 50 000 homes?”
We know that reverse osmosis is just one aspect of water management, but upon investigation it is incredible to note that by merely making incremental changes, it is in fact possible to create a massive impact when done so at scale. Yes! As massive as conserving enough energy to power 50 000 homes.
It is estimated that at least 50% of RO Plants worldwide are impacted by biological fouling.
Let’s take a closer look at understanding the simple choices that could make this a reality.
3 strategies to combat the inefficiencies found in RO Plants:
1. Fouling Management
What is Fouling?
Fouling is the process resulting in loss of membrane performance due to the deposition of suspended or dissolved substances on its external surfaces, at its pore openings, or within its pores.
- Deposition of colloidal particles
- Natural organic matter
- Effluent organic matter
- Synthetic organic compounds
- Microbial growth
- Extracellular polymeric substance excreted from micro-organisms
A deeper look at biological fouling
Biological fouling is the accumulation of microorganisms, plants, algae, or small animals on wet surfaces that have a mechanical function, causing structural or other functional deficiencies. In membrane plants, most of the time we are dealing with bacteria.
How to formulate an effective fouling management strategy
There is no simple one size fits all solution due the uniqueness of each application wrtchemistry, application and business drivers.
Prevention is better than cure
- Physical pre-treatment: Clarification, DAF, MMF, UF
- Chemical pre-treatment: Oxidation/Reduction, Non-oxidizing biocides (DBNPA, Isothiazolone, enzymatic products)
- Select the right membrane for the job (Surface manipulation, spacer design, CIP robustness)
- Use the most effective cleaning strategy
1. Select the correct membrane
- More neutral surface charge
- Inhibits bacteria attachment and growth
- Low adhesion of colloidal particles
- Less susceptible to bio-growth
- Operational dP 25% less. Less energy!
- No loss of rejection (constant concentration polarization).
- Improved fluid dynamics, less low flow zones leading to fouling
- Easier to clean, more effective CIP’s
2. Use the most effective cleaning strategy
Step 1: Understand the fouling by performing an autopsy first.
Step 2: Perform a labscale cleaning trial to confirm the best course of action.
Step 3: Clean pre-emptively to reduce lifecycle cost
- Fouling easier to clean
- Quicker cleaning
- Reduction of the fouling rate
- Increase in membrane life due to less exposure to chemicals. Reduced risk of mechanical damage
- Saving chemicals, water, energy and manpower
2. Scaling Management
What is Scaling?
Scaling is the deposition of minerals (i.e., carbonates, sulphates, phosphates, silica, iron, aluminium, and manganese) on a membrane, causing it to plug.
Scaling causes the nominal flux to decrease, resulting in:
The consequences are:
- Higher energy use
- An increase in the cleaning frequency and
- Shorter life span of the membranes
Adding anti-scalants to the system can prevent the precipitation of salts.
What are Anti-Scalants?
Antiscalants are pre-treatment chemicals that are used in Reverse Osmosis water purification process to prevent the Reverse Osmosis Membranes from scaling. It therefore plays a very important role in maintaining the quality and life of Reverse Osmosis Membranes.
A membrane filtration unit performs optimally at a maximum conversion and a minimal dose of anti-scalants, without the occurrence of scaling.
How to formulate an effective scaling management strategy:
Selecting the correct anti-scalant
The selection of the correct product is supported by UDEC’s and KleinScale’s proprietary solubility modelling software.
By understanding the inorganic water chemistry we can;
- Manipulate pH to suppress scale formation
- Select the right anti-scalant to further increase recovery
3. Design Considerations
Membrane selection & configuration
It all starts with selecting the correct membrane.
Getting the best out of your membrane!
Chemical conditioning of RO feed water is critical to ensure maximum membrane life and performance. Poor RO pre-treatment can lead to membrane fouling, degradation, and overall poor performance if the RO feed water is of subpar quality.
- pH control
- Anti-scalant dosing
Part of the bigger picture
The evolving implications of global warming is always something that we should be cognizant of.
As temperature levels continue to fluctuate, we are increasingly turning to seawater and groundwater as alternative sources. While severe rainfall in certain regions also leads to an influx of contaminants in these water sources, resulting in a greater reliance on reverse osmosis solutions.
Sometimes when removed and not directly affected by an issue, we know that it is easier to believe that it’s not our problem to solve; or that our efforts would be in vain. At UDEC, we believe that the key to making better decisions is being mindful that everything we do has a ripple effect and we are in control of whether it is positive or not.
From how we manage our water supply, to how we process it and ultimately use it too. We all do have a part to play. Bit by bit, collectively we can in fact accelerate change to solve the water and sanitation crisis.
RO Plant efficiency is just one aspect of how to better manage our water supply, imagine what we can achieve if we can adopt this approach in all we do.
Let’s face it, we all need water; without it, what are we?
So let’s all play our part