Sodium Bicarbonate Dosing Systems: Lower Carbon Powder Alkalinity Dosing for AMP8

A pioneering water company in the UK worked with Rospen to retrofit alkalinity and pH correction systems to meet AMP8, PR24 and Net Zero 2030 goals. The utility adopted powder systems for sodium bicarbonate dosing to reduce its operating costs, carbon and risk, as well as to enhance process stability, in lieu of heated liquid caustic soda storage and dosing.

Client Challenge: Upgrading Alkalinity Dosing for AMP8 and Net Zero

The utility was using silos filled with 32% liquid sodium hydroxide, and the tanks were delivered regularly; heating the tanks to the dosing temperature was energy-intensive. This resulted in increased chemical and energy costs, increased HGV movements, spill risks, health and safety issues, and a negative impact on AMP and ODI performance targets.

The client required a powerful, reliable alkalinity dosing solution that would:

• Minimise chemical & energy OPEX.
• Reduce transportation activities and their carbon footprint.
• Enhance resilience and security of stock in multiple locations.
• Provision of support for efficient operation of the AMP8 and Net Zero goals.

Rospen’s Sodium Bicarbonate Dosing System Solution

Fully engineered sodium bicarbonate dosing systems designed and delivered by Rospen using dry powder storage, accurate loss-in-weight metering, and controlled slurry generation. The overall system provides superior value, handling safety and carbon savings.

Major solution elements were:

• Powder silo storage – 5m³ and 45m³ sodium bicarbonate silo storage with load cells, flow aids and ABS anti-frost pipework, giving up to 112 days of storage, depending on site throughput.
• Loss-in-weight screw feeders – stainless steel Rospen feeders providing accurate powder dosing from 0.75 kg/h up to almost 60 kg/h to washdown hoppers for slurry dosing.
• Turnkey kiosks and containerised systems – GRP kiosks and mobile containerised systems for sites with lower or unknown demand, with 25 kg sacks, buffer hoppers and vacuum conveying for flexibility.

Every installation was designed to WIMES and client specifications, and included mechanical, electrical, control and instrumentation design as well as on-site commissioning and operator training.

Implementation: Powder Alkalinity Dosing for AMP8

Rospen has collaborated closely from feasibility to commissioning each dosing system to meet the demands of AMP8 and any specific site needs.

Engineering work included: Plant and process design, Mechanical and Electrical installation, Panel building, Software development and complete plant commissioning.

Rospen used modular, mobile containerised sodium bicarbonate dosing systems on multi-site portfolios and lower-flow works, which can be easily moved as priorities change with AMP. Manual handling is controlled and safe, with operators filling powder buffer hoppers using 25kg sack handling systems equipped with a suction lance.

Results: OPEX and Carbon Savings from Powder Alkalinity Dosing

The changes from using heated liquid caustic to using powder dosing of sodium bicarbonate were found to provide significant financial, operational and sustainability benefits.

Headline savings:

• Chemical cost savings: Typical caustic IBC pricing (using a 32% caustic) of (e.g. £750 with a 320 kg active caustic) is compared to 1,000 kg sodium bicarbonate (e.g. £882), yielding around 21% chemical cost reduction per equivalent 1,000 litres of dosing volume.
• Overall alkalinity-related OPEX reduction: Combining chemical, energy, transport, and maintenance costs indicates that OPEX was reduced by about 20-35%.
• Due to the energy savings, Scope 2 site energy and operational carbon are reduced, from approximately 15 – 25 MWh per year to approximately 2 – 5 MWh per year.
• Embedded transport carbon is lowered by approximately 20 – 40% and community safety and site access are improved due to a reduction of 30 – 70% in HGV/tanker movements.

Additional benefits included:

• Stable and buffered pH control to minimise the risk of overshoot and stabilise biological treatment.
• Minimise the risk of discharge consent violations and pollution events that relate to performance protection of the ODI.
• Safer handling vs. corrosive liquids, with reduced COSHH burden, lower PPE requirements and reduced severity in the event of a spill.

These changes are estimated to reduce operating costs by around £45k to £60k per annum across a typical site and directly contribute to the efficiency and AMP8 Net Zero objectives of the TOTEX.

Why Powder Sodium Bicarbonate Instead of Liquid Caustic?

In terms of alkalinity equivalence, sodium bicarbonate will provide about +0.60 kg of alkalinity as CaCO₃ per kg of product while sodium hydroxide will provide about +1.25 kg of alkalinity as CaCO₃ per kg of product. It requires more mass (per pH) for this type of pH correction, but with the lower cost of chemistry per unit alkalinity, lower energy usage, and reduced transport needs, the total cost of ownership is lower.

Powder sodium bicarbonate is non-corrosive and much safer to handle than liquid caustic soda, as it presents a lower risk of chemical burns, spill consequences and risk of hazardous transport classification. The buffering properties of sodium bicarbonate also make it easier to dose and prevent downstream processes from shock doses.

Why Partner With Rospen for AMP8 Ready Dosing Systems?

Rospen has over 50 years of specialist experience in dry chemical powder storage, weighing and metering systems for the water industry.

A world-class engineering team delivers site-specific solutions, with a focus on compliance, performance, safety and lifecycle cost reduction.
Services comprise plant and process design, mechanical and electrical engineering, control and instrumentation, panel construction, installation, commissioning, operator training and after-sales support. This relationship-focused approach helps equip water utilities with a long-term technical partner to meet the requirements of AMP and Net Zero in their asset portfolios.

To explore powder alkalinity dosing for the AMP8 and Net Zero system, speak with the Rospen staff about sodium bicarbonate dosing systems that lower OPEX, carbon, and risk, and increase compliance and resilience.