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Improve coagulant dose control on your water and wastewater treatment plants


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Compass is a predictive coagulant control system that continuously optimises dosing

Compass is a predictive coagulant dose control system that continuously optimizes dosing for both water and wastewater treatment plants.

Coagulant dose requirements are determined by characterizing and measuring the quality of the water to be treated. Measurement is by a turbidity meter and UV-Vis meter. The Compass algorithms run in either the UV-Vis meter or in a standalone controller depending on the model selected.

Compass reduces operating costs and improves treatment plant process reliability by determining the coagulant demand of raw water or treatment plant influent and reacting instantly to changes in raw water / influent quality. Thus, ensuring the correct coagulant dose at all times.

The basic Compass model is designed for turbidity removal in drinking water treatment. It requires a single UV-vis spectrophotometer and a turbidity meter on the raw water. This model controls coagulant dosing to meet filtered water turbidity targets at the lowest dose rate. The Compass software runs within a UV-Vis spectrophotometer controller.

The enhanced organics removal (EOR) model is designed for dissolved organics removal in drinking water treatment. It provides the optimum dose to meet filter turbidity targets plus maximizing dissolved organics removal at the lowest coagulant dose. It requires a UV-vis instrument and turbidity meter on the source water and a UV-Vis meter on the filtered water. The Compass algorithms run within a stand- alone controller.

The chemical phosphate removal (CPR) model is designed for P removal in wastewater treatment. It provides the optimum dose to meet P discharge targets at the lowest coagulant dose. It requires a single UV-vis instrument on the influent prior to coagulant dosing. The Compass algorithms run within the UV-Vis instrument controller.

The chemically enhanced pre-treatment (CEP) model is designed for pre-treatment in wastewater treatment. It provides the optimum dose to meet performance targets at the lowest coagulant dose. It requires a single UV-vis instrument on the influent prior to coagulant dosing. The Compass algorithms run within the UV-Vis instrument controller.


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Source water turbidity and the type and amount of dissolved natural organic matter (NOM) changes very rapidly, and trying to maintain an optimum coagulant dose using existing techniques, such as operator experience, jar testing and streaming current control, results in over-dosing of coagulant and frequent plant failures.

Meet filter turbidity targets under all conditions at the lowest coagulant cost.


Return on investment ranges from 6 to 24 months

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Eliminate under-dosing while reducing risk of plant failure.

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The removal of natural organic matter (NOM) in drinking water is important for health, aesthetic and operational reasons. The presence of NOM can lead to; colour, taste and odour issues, increased coagulant and chlorine demand,reduced efficiency of UV disinfection, membrane fouling, microbial growth in distribution systems and most importantly the formation of disinfection by-products (DBP’s).

Meet filter water NOM targets under all conditions at the lowest coagulant cost.


Compass has improved coagulant dose control for these organisations

  • Tauranga City Council - Company Logo
  • Horowhenua District Council - Company Logo
  • Severn Trent - Water Services Company Logo
  • Wellington Water - Water Industry Company Logo
  • Sydney Water - Dairying company Logo

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Phosphorus removal is often achieved by dosing coagulant to treated effluent and allowing the flocculated particles to settle or be removed by filtration before discharging. The dose can be set manually by measuring influent and effluent phosphorous concentrations and carrying out jar testing. Compass CPR provides an alternative which will continuously adjust the dose to the optimum level, accounting for all components of the coagulant demand.

Meet P discharge targets under all conditions at the lowest coagulant cost.

Read the case studies



Chemically enhanced pre-treatment involves dosing coagulant to the primary clarifiers in order to increase the capacity of a wastewater treatment plant. Compass CEP predicts the coagulant demand in the influent, in order to achieve the required treatment quality in the primary effluent.

Meet pre-treatment performance targets under all conditions at the lowest coagulant cost.

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