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Chemical Dosing Systems

Right chemical, right amount, right time — automatically. Dosing is where most treatment plants lose money and compliance; we engineer it to be boring.

Why dosing deserves engineering

Chemical cost is often the largest operating expense of a treatment plant after power, and overdosing is the norm when pumps are set once at commissioning and left alone. Underdosing is worse — a coagulant pump that trips or a hypochlorite tank that runs dry means outlet failure. A dosing system is not a pump on a drum; it is storage, preparation, metering, control, containment and instrumentation designed together.

We engineer dosing systems for every chemical used in water and wastewater treatment: coagulants (alum, PAC, ferric), polyelectrolytes (dry and emulsion), lime and caustic, acids, antiscalants, oxidising and non-oxidising biocides, sodium hypochlorite, sodium metabisulphite, nutrients and defoamers.

What a complete dosing system includes

Process flow — typical sequence
Storage and daytanks01Preparation02Metering03Control04Injection05Safety06Instrumentation07
  1. Storage and day tanksHDPE, PP or FRP tanks with level switches, bunding for 110 % containment, vent and overflow to safe location.
  2. Preparation (where required)Automatic polyelectrolyte preparation units — dry powder or emulsion — with hopper, wetting cone, ageing and dosing chambers; lime slurry make-up.
  3. MeteringDiaphragm or peristaltic metering pumps sized for turndown, duty/standby, with pulsation dampeners, back-pressure and relief valves, calibration columns.
  4. ControlFlow-proportional (4–20 mA from flow meter), pH, ORP or residual-chlorine feedback, timer or PLC-based; local panel or integration with plant SCADA.
  5. InjectionInjection quills, static mixers, dilution water and check valves at the right point in the process.
  6. SafetyEye-wash and shower, PPE stations, leak detection in bunds, segregation of incompatible chemicals (hypochlorite and acid never together).
  7. InstrumentationLevel, flow, pH, ORP and residual analysers so consumption is measured, not estimated.

Systems we supply

Coagulant / flocculant skids

PAC, alum, ferric — flow-proportional dosing for ETP, STP, WTP clarification.

Polyelectrolyte preparation units

Automatic 2- or 3-chamber units, 0.1–0.5 % solution, 500–10,000 L/h.

pH control systems

Acid and caustic dosing with pH controller for neutralisation and RO feed.

Antiscalant / SMBS skids

RO pre-treatment dosing with flow pacing and low-level alarms.

Chlorination systems

Sodium hypochlorite or gas chlorination with residual control for disinfection.

Biocide dosing (cooling towers)

ORP-controlled oxidising and timer-based non-oxidising programmes.

Lime dosing

Slurry preparation, agitated tanks, hose or peristaltic dosing for pH and precipitation.

Nutrient / defoamer dosing

Urea, DAP, defoamer for biological plants.

Applications

Effluent treatment plants
Coagulation, flocculation, neutralisation, nutrient balancing, sludge conditioning for filter presses.
Sewage treatment plants
Chlorination, polymer for sludge dewatering, alum for phosphorus removal.
Water treatment plants
Pre-chlorination, coagulant, lime, post-chlorination with residual control.
RO and membrane systems
Antiscalant, SMBS, acid and CIP chemical dosing.
Cooling towers and boilers
Scale and corrosion inhibitors, biocides, oxygen scavengers, amines.

How KK Enviro Engineers delivers

Chemical and dose-rate calculation from your process data → P&ID, pump sizing and material selection → skid fabrication with panel and instrumentation → FAT, installation, commissioning and operator training. Standard skids ship in 4–6 weeks; we also retrofit dosing on existing plants and supply the chemicals themselves.

Frequently asked questions

How do you size a dosing pump?

From the maximum chemical demand (flow × dose × concentration factor) with 20–30 % margin and a turndown that still covers minimum flow accurately. We select duty/standby pumps and the pump type from chemical compatibility and pressure.

Diaphragm or peristaltic dosing pump?

Diaphragm pumps for most chemicals and higher pressures; peristaltic for slurries (lime), viscous polymers and gas-forming chemicals such as hypochlorite where lock-up is a problem.

What is a polyelectrolyte preparation unit?

An automatic system that wets, dissolves and ages dry or emulsion polymer into a 0.1–0.5 % solution ready for dosing — consistent solution quality means 20–40 % less polymer than manual mixing.

Can dosing be controlled automatically?

Yes — flow-proportional dosing from a flow meter signal, and feedback control from pH, ORP or residual-chlorine analysers. We integrate with existing PLC/SCADA or supply a local panel.

Dosing costing too much or failing too often?

Send the chemical, process flow and current dose — we reply with a sized dosing system and expected savings within one working day.