Model DF-340
Caustic Replacement

DF-340 is a unique non-hazardous reagent developed to replace hazardous sodium hydroxide (caustic soda) solutions for neutralization of acidic wastewaters in many industrial pH adjustment applications.

Due to our exclusive dispersing/ stabilization technology, DF-340 also eliminates the historical cost and metering system problems associated with use of lime for neutralization.

The product consists of calcium hydroxide blended with dispersants/stabilizers that permit easy preparation of slurries, containing up to 38% by weight calcium hydroxide that can be easily metered via typical chemical feed systems. Normal calcium hydroxide/water mixtures at 38% solids are a "solid," which is not pumpable at all.

Lime slurries - a frequent alterative to sodium hydroxide - provide lower neutralization costs and various chemical benefits. However, these have historically been used in only the largest wastewater treatment systems due to the cost and operating problems associated with the slurry make-up and metering system.

Replacement of caustic soda with DF-340 will provide benefits normally associated with lime neutralization at much lower cost of ownership:

  • Increased removal of heavy metals and organics from the wastewater due to superior coagulation
  • Formation of a denser, faster to settle floc; and
  • Formation of an easier to dewater sludge.

Unlike caustic soda, DF-340 is not a hazardous material and is not regulated under SARA Title III. Consequently, there are substantial regulatory benefits from caustic replacement as well as a decreased health and safety concerns.


DF-340 can be utilized for neutralization of any industrial wastewater that will not be recycled or reused. Typical process design would consist of adding any primary precipitants or coagulants, pH adjustment with DF-340 (vigorous mixing recommended), followed by polymer addition, sedimentation, and filtration, if needed. Use of DF-340 is compatible with most automatic pH control circuits and systems, and thus can be easily integrated into existing wastewater treatment systems. Please contact Duarflow for a detailed evaluation and design assistance.

Case History

A major plating job shop in Massachusetts recently replaced caustic soda with DF-340. Because the shop already had a suitable mix tank and mixer on-hand the only expense of the conversion was the purchase of a peristaltic feed pump. The major reason for this conversion was environmental - to replace a SARA Title III hazardous material, with a non-SARA Title material. Results of the conversion were excellent. The shop reports that their effluent metals values were lowered and that the produced sludge was easier to dewater.

A second DF-340 application occurred when this same manufacturer completed a sequential batch system to treat wastewater from wet finishing of lead crystal glass. Because the company wanted to eliminate use of any SARA Title III materials in the wastewater treatment process, it replaced the caustic soda (specified for neutralization in the original design) with DF-340. Results to date have been excellent. The plant discharge has complied with effluent standards for pH and lead, while the produced sludge is readily dewatered to a dense cake.

  • Substantial improvement in plant safety
  • Lower freezing point than sodium hydroxide
  • Faster settling floc
  • Better removal of heavy metals and organics
  • Better dewatering of produced sludge
  • Not SARA Title III regulated
  • Improved flux in crossflow microfiltration systems
  • Reduced cleaning requirements for crossflow microfiltration systems
  • Reduction or elimination of additional coagulants

Physical Data (Typical)
Odor: Slight
Form: Slurry
Freezing Point: 32°F
RCRA Class: Non-hazardous
DOT Class: Non-regulated, Non-hazardous
pH 38% slurry : 12.5/12.9 su
SARA RQ: none

Scroll to top