A conventional industrial wastewater lime treatment plant is a proven, reliable system for treating industrial wastewater. This process involves adding lime (calcium hydroxide) and/or caustic soda (sodium hydroxide) to raise the pH level, which causes heavy metals, suspended solids, and other contaminants to precipitate and form insoluble compounds.

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The treatment typically includes a mixing chamber, flocculation basin, and sedimentation tank to separate the solids from the treated water before discharge. Lime serves as the primary chemical agent for neutralizing acidic waste and removing pollutants through precipitation.

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The key components of a conventional industrial wastewater lime treatment plant include:

1. Lime and/or Caustic Addition: A precision dosing system accurately introduces the appropriate neutralizing chemical into the incoming wastewater stream to ensure consistent and effective pH adjustment.

2. Reactor Tanks: These tanks serve as mixing chambers where the neutralizing chemical is thoroughly dispersed throughout the wastewater to initiate the chemical reactions and pH adjustments. Typically, the system uses two reactor tanks equipped with mixers, chemical feed systems, and automated pH control.

3. Flocculation Basin: This basin provides gentle mixing to encourage the precipitated solids to aggregate into larger particles (floc), making them easier to settle and remove.

4. Sedimentation Tank (Clarifier): A large tank where flocculated solids settle to the bottom as sludge, while clarified water flows to a final effluent tank. Here, the water undergoes verification testing before being discharged to a publicly owned treatment works (POTW) or under a National Pollutant Discharge Elimination System (NPDES) permit.

5. Sludge Handling System: The sludge handling process uses a filter press to dewater the metal hydroxide sludge, forming a filter cake that is disposed of in a landfill as either hazardous or non-hazardous waste, depending on the composition.

This conventional wastewater treatment system can be enhanced with additional zero liquid discharge (ZLD) components. Adding ZLD capabilities can increase water recycling rates to as much as 80%, eliminating the need for a discharge permit entirely.