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Concrete Wastewater Treatment

The worldwide expansion of commercial concrete production and manufacturing can generate increased levels of industrial wastewater pollution. To counteract strict concrete wastewater discharge regulations and the high wet-tonnage disposal costs, the concrete industry is turning toward methods for treating and recycling concrete process water.

ALAR Engineering provides the concrete industry with wastewater pretreatment and dewatering filter equipment designed to remove cement fines and iron oxide color pigments. ALAR industrial concrete water recycling filter systems are ideal for ready mix and precast concrete producers dealing with high return rates, color and high-strength concrete wash-up. ALAR’s time-proven equipment can enhance concrete reclaimer efficiency, remove suspended solids, eliminate weirs and pond dredging, and reduce wet tonnage concrete slurry hauling costs.

Concrete washout or process water is a high pH slurry containing metals, chemical admixtures, trace amounts of oil and grease, along with dissolved and suspended solids.

ALAR’s compliance and equipment solutions work for a variety of industrial concrete wastewater applications that include, but are not limited to:

  • Ready Mix Concrete
  • Concrete Block
  • Brick & Stone
  • Concrete Pipe
  • Structural & Architectural Precast Concrete
  • Concrete Core Drilling
  • Concrete Pigments / Color
  • Hydro Demolition
  • Roofing Tile
  • Sawing / Grinding / Grooving / Polishing
concrete slurry mix

Concrete Wastewater Discharge Compliance

Environmental agencies monitor and limit the levels of industrial wastewater contaminants a facility can discharge into sewers and waterways. To comply with discharge limits, the concrete industry is required to lower pH and reduce total suspended solids (TSS). Another option is to reclaim the aggregate, then filter out the cement fines and recycle the water.

Popular solutions for concrete wastewater management include settling ponds, sloped pits with overflow weirs, holding tanks and pH adjustment. However, the systems can be restricted by limited space, residential expansion, weather, and constant dredging. These conventional methods for concrete water recycling efforts can be impeded by color pigments, high specific gravity and reclaiming issues.

ALAR Engineering Corporation is a direct manufacturer of liquid-solid separation equipment. ALAR custom builds concrete wastewater treatment and filtration systems that can be integrated with mechanical reclaimers and existing concrete washout processing equipment.

Contact ALAR to help determine the best solution for your concrete operation.

Industry Details

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ALAR has redefined water recycling equipment for the concrete industry.

The Auto-Vac® is a rotary vacuum drum filter that removes cement fines and color from concrete waste, yielding 1.0 specific gravity colorless water and exceptionally dry solids. It is the only self-cleaning filter (non-clogging) on the market. This is ALAR’s flagship model that works best for precast and ready mix producers dealing high return rates, color, and high strength concrete.

The Auto-Vac® is best for activated concrete; available in sixteen filter sizes for virtually any volume of concrete slurry water.

The Sludge Settling Clarifier & Micro-Klean™ is an easy to operate combination system that removes solids from water and produces a clean effluent.

The Clarifier produces a clear effluent through the separation of liquid from settling solids. Concentrated heavy solids “sink” to the bottom of the clarifier and are pumped to a dewatering filter.

The Micro-Klean™ plate-n-frame dewatering filter press is primarily used in block and brick operations. It is excellent for cured concrete applications where the solids will not blind the filter cloths.

ALAR Provides Wastewater Solutions for Concrete Industries:

Ready Mix Concrete Wastewater Filtration, Treatment and Recycling

Precast Concrete Wastewater Filtration, Treatment and Recycling

Concrete Block Water Filtration and Recycling

Concrete Roofing Tile and Iron Oxide Pigment Wastewater Filtration, Treatment and Recycling

Brick & Stone Veneer Wastewater Filtration, Treatment and Recycling

Concrete Sawing/Grinding/Grooving/Polishing Wastewater Filtration, Treatment and Recycling

Concrete Core Drilling Water Filtration and Recycling

Concrete Pipe Wastewater Filtration, Treatment and Recycling

Concrete Color Pigment Process Wastewater Filtration, Treatment and Recycling

Hydro Demolition Concrete Slurry Water Filtration and Recycling

...Along with many other industrial concrete washout applications

ALAR Auto-Vac® Cement Fines Filter & Water Recycling System

General sequence of operation

The Auto-Vac® is a self-cleaning dewatering filter that separates water from cement fines, generating 1-micron clean, recyclable water; and producing dry, manageable solids for easy transport or reuse.

The Auto-Vac® is not a rock and sand reclaimer; rocks, heavy sand, and slugs of fiber should be removed prior to filtration.

On average, the Auto-Vac® will operate within a six-hour batch. Variances in cement fines and solids buildup [SG] in the water will influence the Auto-Vac® filtration rates.
 
After successfully reclaiming the rock & aggregate, the slurry-water (containing active concrete cement fines) is pumped into an agitated holding tank. The objective is to keep the solids in suspension and not let the active concrete settle/ set in the tank. The slurry-water is pumped from the mixing tank to the ALAR Auto-Vac®.

(If Necessary) Prior to reaching the ALAR system, a metered amount of polymer is injected into the filter feed line and blended with the slurry through a series of in-line 90o “injection” feed pipes. The polymer increases the micron size of the cement fines; allowing for faster filtration, cleaner effluent, drier solids, and conserves diatomaceous earth (the consumable filter media used during the Auto-Vac® operation).

The polymer-treated slurry water feeds into the ALAR Auto-Vac® filter system. The suspended solids accumulate on the surface of the filter drum and 1-micron clean water is vacuumed through the diatomaceous earth filter media. A variable speed knife advances, removing the solids from the drum surface with lathe-like precision; leaving a clean layer of filter media to capture more fines.

The filtered water is pumped into a non-potable clean water tank for reuse in the batch, reclaiming, and washout process; depending upon the company’s QA requirements.

The dewatered, filtered cement fines are easily collected for transport off site or potential reuse. The dry solids will have the consistency of damp sand.

As an added benefit, the Auto-Vac® filter can be occasionally run when the batch plant is not in operation to clean the tank or weir bottom(s), yard and runoff water.

Ready Mix Washout (Cement Fines Slurry Water)

NOTE: Remove Rocks/ Aggregate, Heavy Sand, and Fibers prior to Filtration

Estimated Filtration Time = 6 Hours (One Batch)

One Yard Returned Concrete Yields Approximately 675 Lbs. Cement Fines

Auto-Vac®

Average Total

Average Total

Average Total

Model

Return Yards Capacity

Per 6 Hour Filter Time

Pounds of Fines Capacity

Per 6 Hour Filter Time

US Gallon Capacity

Per 6 Hour Filter Time

AV220 4 2,700  1,000 - 1,500
AV230 6 4,000 1,500 - 2,000
AV330 9 6,000 2,000 - 3,000
AV340 12 8100 3,000 - 4,500
AV360 18 12,000 4,500 - 7,000
AV640 24 16,200 7,000 - 9,500
AV650 30 20,250 9,500 - 11,500
AV660 36 24,300 11,500 - 14,200
AV690 54 36,450 14,200 - 21,400

The ALAR Engineering Department designs each system to meet the customer's build-to specifications. ALAR begins with stock layouts, and customizes the auxiliary equipment according to the customer's specifications.

These stock layouts are available in PDF format.  Contact ALAR for more information.

Case Studies

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