Unconventional times call for unconventional solutions.

NuWater prides itself on being a technology-led water treatment services provider. In today’s times, clients are redirecting capital expenditures to renewable energy and ensuring business continuity due to constant load shedding. There is little room left over in annual capital budgets for initiatives in other focus areas, such as water.  Although it can be argued that there is no water without power, the requirement for water in almost every process remains. In most instances, managing or disposing wastewater is integral to many industries. 

The Challenge of Affordable Water Treatment

The demand for clean and safe drinking water is constantly increasing, while the need for manufacturing processes to continue remains high. As a result, both industrial and municipal clients are confronted with the challenge of treating water at the most affordable cost, all while satisfying the demands of their operations. 

In 2018 NuWater was awarded a contract to treat borehole water at a leading clothing manufacturer. The treatment requirement saw the implementation of standard technologies to reduce iron and manganese content and manage salinity in the water to potable standards.  

These technologies included pH adjustment, chemical conditioning, clarification, media filtration, iron removal media filtration, micron filtration, and reverse osmosis before final water disinfection.

While the above strategy would be a belts and braces approach, it did not perform as anticipated. 

The system was designed to treat feedwater containing >10mg/l of iron (Fe), ~1mg/l of manganese (Mn), coupled with >3 000mg/l of hardness and a salinity of ~15 000mg/l of TDS.

The complexity of the feedwater, coupled with the client’s limited space on site, meant that adding greater system volume to allow for even slower settling and filtration rates was impossible.

The issue encountered was 5 pronged:

1.  The client’s limited space on site necessitated as compact an installation as possible.
2. Variation in the borehole feed supply rate over the course of a day was hampering the performance of the settling equipment by not being able run at a constant rate without flow upsets.
3.  The high iron and manganese necessitated a higher than ideal pH for effective removal.
4. Feed water complexity was exacerbated by the presence of high hardness and alkalinity forcing precipitation and deposition of carbonate scale with the metals in pipes and equipment.
5. By virtue of the pH requirements and the resultant solids forming a light, porous and difficult to settle floc there was a requirement for lower flow rates and larger settlers, however, with no additional space available to implement this. The primary concerns identified were the extensive reliance on chemistry and space limitations. 

A No-Brainer Solution for Heavy Metal Removal in Water Treatment

Having experienced similar difficulties in an extensive mining application, albeit not to the same degree, NuWater decided at its cost and risk to replace the conventional with the unconventional as a proof of concept.

In 2012 NuWater designed and developed an operational strategy using ultrafiltration that could not only manage heavy metal concentrations in feedwaters but also reduce the concentrations to lower levels at far greater efficiencies by reducing the reliance on chemistry considerably. The reduced chemical requirement and the reduced burden of capital expenditure constructing enormous and immovable settlers made the envisaged solution a no-brainer.

These learnings have been constantly improved over several years, and in 2018 at the clothing manufacturer, we had an opportunity to establish the actual viability of such solutions at far higher concentrations of metals.

At the time, the mining site’s ultrafiltration membranes had provided five years of consistent performance which were eventually incrementally replaced after giving seven years of service. The membranes were replaced for a higher flow, lower energy version at a lower cost than the originals.

The baseline data on the mining site and access to higher flow, lower energy ultrafiltration membranes meant that replacing the conventional for the unconventional was worth the risk. 

Four years after replacing the conventional solution with a modified ultrafiltration system at the clothing manufacturer, the system is still performing as anticipated and is expected to keep doing so for another year or two before the newer, more improved ultrafiltration modules already available have been implemented at sufficient scale to provide comfort that the performance improvements will be worth the exchange. 

Experiencing similar concerns or have a unique application? Don’t hesitate to contact. 

Keep an eye out for more information on how the system described above operates.