CP Systems for Chemical-Physical Wastewater Treatment

A CP plant is a chemical-physical wastewater treatment plant. It combines chemical processes such as neutralization, precipitation, coagulation, and flocculation with physical separation processes such as sedimentation, flotation, or filtration.

The goal is to convert dissolved, colloidal, or suspended substances in industrial wastewater into a form that can be separated. The resulting solids are then removed from the water and further treated as sludge.

Depending on the water chemistry and process design, the following substances, among others, can be reduced or removed:

• Heavy metals such as nickel, copper, zinc, chromium, or lead
• Phosphorus and Phosphates
• Fluoride and other precipitable anions
• suspended solids and turbidity
• colloidal particles
• Hardness-forming substances and carbonates
• Oils, fats, and suitable emulsions
• Pigments, paint components, and mineral particles

The achievable treatment performance depends, among other factors, on the concentration, form of binding, complexation, pH, temperature, and other constituents of the wastewater.

In precipitation, dissolved substances are converted into poorly soluble solids through a chemical reaction. A typical example is the precipitation of dissolved metal ions as metal hydroxides or metal sulfides.

During flocculation, these fine precipitates and other particles are aggregated into larger flocs. This makes it easier to subsequently settle, float, or filter them.

Precipitation and flocculation serve different purposes, but are often combined directly in a CP system.

A batch system is particularly well-suited for:

• small volumes of wastewater or wastewater generated intermittently
• compositions that fluctuate widely
• highly concentrated partial currents
• Controlled processing of individual batches

A continuous-flow system is particularly well-suited for:

• regular wastewater flows
• medium to high flow rates
• automated continuous operation
• largely continuous production processes

The selection depends on the volume of wastewater, fluctuations in load, the production process, monitoring requirements, and the available installation space.

Flotation is often advantageous when the flocs formed have a low density and settle only slowly or incompletely.

Typical use cases include:

• light flakes
• Fats and Oils
• Emulsions
• organic solids
• particles that do not settle easily

In pressure-relief flotation, fine air bubbles attach themselves to the solids and carry them to the water’s surface. For heavy, mineral-rich, and easily settable flocs, however, sedimentation or lamellar separation is often more suitable.

For complex, variable, or previously unknown industrial wastewater, laboratory or pilot-scale tests are highly recommended.

The following parameters, among others, can be examined:

• appropriate pH range
• appropriate precipitant and flocculant
• Required chemical dosage
• Flocculation and Settling Behavior
• Sludge Volume and Dewaterability
• achievable process quality
• Possible interactions with other ingredients

The results reduce design risk and provide a solid foundation for planning, investment, and operation.

The following information is particularly helpful for an initial technical assessment:

• Source and Type of Wastewater
• Average and maximum flow rate
• continuous or batch-based wastewater generation
• Latest water analyses
• Relevant target substances and concentrations
• Required flow or discharge values
• Existing pre- and post-treatment
• available installation space
• Requirements for Automation and Sludge Treatment

The more complete this data is, the more accurately the process concept, plant size, and potential project scope can be assessed.

Yes. A CP system can be used as a standalone treatment process or integrated into an existing plant as an additional treatment stage. Possible applications include pretreatment prior to a biological wastewater treatment plant, the removal of specific contaminant loads from a partial flow, or pretreatment prior to filtration, membrane technology, and water reuse.

For the integration, factors such as the existing hydraulic system, installation space, interfaces, control technology, and subsequent treatment steps are taken into account.

The operating costs of a CP system depend primarily on chemical consumption, energy requirements, sludge production, disposal costs, and maintenance needs. It is therefore not possible to provide a reliable estimate without knowing the characteristics of the wastewater and the required effluent quality.

Laboratory tests, needs-based chemical dosing, and tailored sludge treatment help reduce the consumption of operating materials and the volume of residual materials. In addition to the investment costs, the long-term operating costs should therefore always be taken into account.