Industrial Waste Water Treatment

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CHEMICAL TREATMENT SYSTEM STL 8-1

CRT Chemical Reaction Treatment Systems

The CRT Series Chemical Reaction Treatment systems are a family of chemical pretreatment designs that provide flocculation, coagulation, flash flocculation, pH neutralization and adjustment, metals precipitation, emulsion breaking and other reactions.

Through implementation of chemical metering, agitation and pH monitoring the CRT systems are tailored to the needs of the application. CRTs are typically used as pretreatment prior to our DAF, SPC and oil water separator systems and can be provided as free standing, individual designs to fit your needs.

Custom tank volumes are offered to match the reaction system to the application

Customization & modifications to fit your project needs are offered. Reaction tanks constructed of steel, stainless steel, FRP and polyethylene are available.

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The CRT Series Chemical Reaction Treatment systems are a family of chemical pretreatment designs that provide flocculation,
coagulation, flash flocculation, pH neutralization and adjustment, metals precipitation, emulsion breaking and other reactions.

Through implementation of chemical metering, agitation and pH monitoring the CRT systems are tailored to the needs of the application. CRTs are typically used as pretreatment prior to our DAF, SPC and oil water separator systems and can be provided as free standing, individual designs to fit your needs.

Custom tank volumes are offered to match the reaction system to the application

Customization & modifications to fit your project needs are offered. Reaction tanks constructed of steel, stainless steel, FRP and polyethylene are available.

Specifications

Specification Summary:
System model
Number of model sizes 
Process  types

Design Specification Summary

Design criteria
Influent
Solids hopper  
Tank  
Mixer  
Mixer impeller   
Chemical metering pump 
pH controller 
Cover                         
Fittings                         
Base                         
Lifting lugs                         

Materials of Construction

Tanks 
Piping
Testing
Surface preparation(steel)
           
Coatings (steel)                                         

Standards used    

CRT Chemical Reaction Treatment Systems
25
Coagulation, flocculation, pH, precipitation, oxidation, reduction
5 – 2000 GPM

 

Reaction tank with agitation and chemical metering system
Influent diffuser or overflow weir
Optional, provided where high solids are expected
Circular, rectangular, multiple tanks for coarse, fine & finer adjustment
Fixed speed, direct/gear drive, universal mount, TEFC motor
Axial flow, 316 SS shaft & impeller(s)
Solenoid actuated diaphragm and motor driven types
Programmable digital display,on/off relay control of pumps
Domed top with 16″ removable access cover
NPT couplings up to 3″, 4″ & larger: 150# ANSI B16.5 FF flange
Steel skid base of channel, beam or tube construction
Provided when required by design

 

A-36 carbon steel, 304/316 SS, FRP, polyethylene, polypropylene
A-53 black steel, 304/316 SS, FRP, PVC
Dye penetrant on steel construction
Interior surfaces will be prepared to an SSPC-SP10 near white metal blast. Exterior surfaces shall be prepared to an SSPC-SP6 commercial blast.
Interior will be coated with Ameron Coal Tar Epoxy Amercoat.
Exterior will be coated with Ameron Amerlock primer.  Final coat to be Ameron Amershield Polyurethane Enamel.
Elements of AWS D1.1/1.1M, API, API-650, API-421, ANSI, IEC,AWS D1.6, UL, UL-508,UL-845,SSPC,ASME, CSA, NEMA, NFPA79, NEC

Theories

Chemical Treatment:

With many waste streams chemical pre-treatment is required to effectively remove contaminants in combination with physical separation equipment such as Slant Plate Clarifiers, DAF and oil water separators.

Chemical processes: Chemical treatment should be considered when your project involves: oil-in-water emulsions, dissolved metals, dissolved solids, suspended solids and colloidal solids.

Coagulation: Virtually all surface water sources contain turbidity. Most of the suspended matter in water is present as finely divided or colloidal particles and these do not settle due to gravitational forces alone. For example in a depth of 1 ft; bacteria would take about 1 year to settle, clay particles would take about 8 hours, sand about 10 seconds.

Colloidal size particles may be formed from soluble compounds (ex. soap. starch, bentonite, carbon) which do not grow into crystals of size large enough to settle or be removed in sedimentation. To assist in the agglomeration of particles, coagulants are used to increase the effective size, which increases settling velocities effective in removing turbidity, color, bacteria, algae and odor producing substances.

Since the properties that prevent the natural agglomeration vary for suspended solids, it is important to review the significant effects.

The majority of particles in surface waters are negatively charged, these like charges cause the particles to repulse, or remain in suspension. Such colloidal suspensions are called stable. Coagulation is an attempt to destabilize the suspensions and allows the particles to come together by neutralizing the particles through the addition of chemicals carrying an electrical charge.

Flocculation: While flocculation is similar to coagulation, it differs in that its purpose is to provide a second, final step of building up particles into a large, heavier mass to speed up the settling or flotation process and more efficiently sweep up all coagulated particles in order to build the larger flock.

pH Adjustment: What is water pH? pH is an indication and quantification of its acid/basic properties. pH is measured on a scale of 0-14. See the reference scale for this range.

pH Range:

pH adjustment is required for several purposes. The most popular purposes are for precipitation of metals, breaking of emulsions, correcting pH for polymer & coagulant use and final pH correction prior to sewer discharge. If the water is basic, an acid, such as sulfuric acid is added to reduce the pH level. If the water is acidic a base such as sodium hydroxide is added to raise the pH level. The particular reagent used to raise or lower the pH is dependent on the nature of the wastewater, abilities, cost and availability of reagents as well as the preference of the end user.

process gets the less reagent is required. The amount of reagent used is dependent on the starting pH level and can be determined by a titration curve.

pH adjustment can be performed on a batch or continuous basis. The chemical metering process can be automated or manually operated as dictated by project or end user.

Emulsion Cracking: Oil-in-water emulsions are very common in groundwater remediation, industrial wastewater, vehicle wash and industrial process waters. Each emulsion is different and each requires jar testing to determine the proper pre-treatment design. Often a two or three stage reaction is successful at breaking most emulsions.

Emulsions Defined: Emulsions are defined as a colloidal suspension of a liquid within another liquid (with droplet sizes typically under 20 micron). A colloidal suspension is a concentration of particles or droplets homogeneously dispersed through the carrier liquid (water). This means the oil droplets are reduced in size to such a degree that the oil’s normal electrical repulsion of the water molecule is overcome due to its minute size.

Oil in water emulsions may contain a variety of oil types and concentrations, as well as various types of solids contaminants. The oil in water emulsion in a stable or unstable state maintains the emulsification through mechanical and/or chemical means.

Emulsions Are Created In Two Ways

Mechanical Emulsions: In mechanical emulsions a common method of creating the emulsion is by violent mixing or shearing of the oil droplet in the waste stream with a high shear transfer pump, vigorous mixer or other device that might disperse the oil droplets into minute droplets. Given enough time, the mechanical emulsion may break without any treatment. But with most processes and manufacturing time frames this time may be too long for practical use.

Chemical Emulsions: Are created when a surface-active chemical or chemicals are used, such as alkaline cleaners containing surfactants, soaps and detergents having ionic or non-ionic characteristics. These chemicals interfere with the natural coalescing of oil droplets and generally creates a permanently stabilized emulsion with little chance of breaking by itself.

Emulsion cracking can be facilitated by the use of a coagulant/flocculent or pH changing chemical(acid/caustic). The chemical used depends on the particular emulsion. These chemicals change droplet electrical charges by the effect of their own charge, usually a cationic (positive) charge. This charge manipulation allows the oil droplets to become free and lets them coalesce (gather together) into larger droplets. The oils don’t always break out of emulsion into a free distinct layer. Sometimes they may be combined with solids or create a light mass that is in suspension, sinks or (usually) floats. The form and appearance of chemical emulsion cracking results can vary quite a bit from emulsion to emulsion. This variation helps to determine the type of equipment and processes required to treat the water.

Coagulation / Flocculation: The destruction of the emulsifying properties of the surface-active agent or neutralization of the charged droplet can be effected with the use of polymer products. A polymer or combination of polymers destabilize the electrical bond between oil and water allowing oils to free themselves, creating droplets and a distinct layer or flocculated mass. Flocculation refers to the successful collisions that occur when the destabilized particles (oil) are agglomerated via a bridging effect due to the flocculating polymer. The polymer acts like a broom, effectively stretching out in the water and bringing many small micro-floc particles together into a larger visible mass. Depending on the nature of the flocculated mass in may sink, float or stay in suspension. Numerous bench tests should be performed to determine the proper chemical types, concentrations and combinations in order to achieve optimum treatment.

Metals Precipitation: Most common metals, when dissolved in a waste stream can be precipitated from their ionic state via an increase in pH level to an optimum point of insolubility, usually in the neutral through low, strongly basic pH range. Typically, a two or three stage reaction system is required to best pre-treat metals for settling prior to a Slant Plate Clarifier or DAF system. A hydroxide precipitation system using a coagulant, sodium hydroxide and a cationic flocculant can be one of the best processes for most of the common metals such as: zinc (Zn), nickel (Ni), iron (Fe), copper (Cu), aluminum (Ag), chromium 3 (Cr3), lead (Pb) and cadmium (Cd).

A common problem with chromium is that it can be frequently found in the hexavalent (Cr6) form in industrial process waters (plating, rinse etc). In order to remove the Cr6 it must first be reduced to the trivalent form (Cr3) via a reduction process using sodium metabisulfite at a pH of 2-3. The closer to pH 2 the faster the reaction. Once the reduction is complete hydroxide precipitation/flocculation can be performed followed by settling.

Chelating agents (i.e. EDTA, DTA) can interfere with the hydroxide precipitation of metals by holding the metallic ion in solution. The chelants must first be neutralized prior to precipitation, jar testing with analytical testing will best identify the proper chemistry.

Models:CRT-CF (COAGULATION FLOCCULATION)

CRT models
CRT-CF-50
CRT-CF-100
CRT-CF-150
CRT-CF-200
CRT-CF-250
CRT-CF-300
CRT-CF-400
CRT-CF-500
CRT-CF-750
CRT-CF-1000
CRT-CF-1500
CRT-CF-2000
CRT-CF-2500
CRT-CF-3000
CRT-CF-4000
CRT-CF-5000

*Flow based on 5 minute reaction time.
*Large sizes available.

Models: CRT-FF (FLASH FLOCC)

CRT models
CRT-FF-50
CRT-FF-100
CRT-FF-150
CRT-FF-200
CRT-FF-250
CRT-FF-300
CRT-FF-400
CRT-FF-500
CRT-FF-750
CRT-FF-1000
CRT-FF-1500
CRT-FF-2000
CRT-FF-2500
CRT-FF-3000
CRT-FF-4000
CRT-FF-5000

*Flow based on 5 minute reaction time, which can vary depending on the project.
*Large sizes available.

Models:CRT-CpF (COAGULATION PH FLOCCULATION)

CRT models
CRT-CpF-50
CRT-CpF-100
CRT-CpF-150
CRT-CpF-200
CRT-CpF-250
CRT-CpF-300
CRT-CpF-400
CRT-CpF-500
CRT-CpF-750
CRT-CpF-1000
CRT-CpF-1500
CRT-CpF-2000
CRT-CpF-2500
CRT-CpF-3000
CRT-CpF-4000
CRT-CpF-5000

*Flow based on 5 minute reaction time.
*Large sizes available.

Influent Feed System

Air operated, diaphragm pump with air controls or progressive cavity, centrifugal or electric diaphragm pumps are offered, sump level switches & Nema 4 control panel, skid mounted, 115/230/460V power offered.

Effluent Pumpout

Centrifugal pump with level switches & Nema 4 control panel, base mounted or tank mounted, 115/230/460V power offered. An external pumpout tank is included.

Tank Covers

Multi-sectioned covers with vapor vents, gasketing and cover hardware are provided to control odor, harmful/controlled vapors

Freeze Protection

Immersion heaters mounted through tank wall. Each heater has an independent thermocouple well, 30-60 deg. F thermostat and Nema 1 (or optional Nema 4 or 7) housing. 230/460V/3ph/60Hz power. Centralized master control panel can be provided (standard on large systems). Explosion proof systems also offered.

Polymer Blending/Aging System

In place of a metering pump & makedown tank a polymer blending/aging system can be provided when polymer consumption volume makes makedown tank size & frequency of making a polymer solution are impractical. Various flow rates can be provided.

Elevation Platform

Epoxy coated steel platforms or leg extensions to elevate tank to desired level can be provided.

Walkways

Walkways can be provided for full or partial SPC tank length to facilitate access to the tank top and internals. Handrails, self-closing safety gates are provided. Ladders or stairs are provided in conjunction with the walkway. A variety of materials can be provided for construction such as: coated carbon steel, stainless steel, FRP or aluminum. Designs are per OSHA standards.

Alarms

High effluent, influent and other alarm systems can be provided as stand alone or in combination with other options to indicate high, low or other conditions and trigger audible and/or visual indicators.

Liquid/Chemical Storage/Feed Tanks

A wide variety of tank volumes can be supplied for your chemical, water and sludge holding needs. Flat bottom and cone bottom designs constructed in polyethylene, fiberglass, steel & stainless steel can be provided.

Effluent Filter Systems

Solids filter systems can be provided to remove light loads of filterable solids from the SPC effluent. Contact Pan America to determine proper filtration needs for your application.

Chemical Makeup/Storage Tank

Coagulants & flocculants requiring makeup to a solution can be provided with a mixer tank to makeup & hold a particular volume as dictated by chemical usage. Typical construction is polyethylene with mixer mounted on top & controls in system control panel.

Explosion Proof Electrical

Electrical components: motors, conduit etc. are provided as explosion proof where required.

pH Adjustment Systems

pH adjustment or pH neutralization systems can be provided separately to maintain pH levels prior to or after the treatment system. Contact Pan America to determine proper system needs for your application.

Vent Carbon Absorber

GAC carbon filters can be provided to treat vapors in covered CRT tanks. Either self-aspirating or blower driven designs can be provided.

Applications

– Frac water
– Produced water
– Refineries
– Biodiesel plants
– Algae removal
– Petrochemical plants
– Groundwater remediation
– Dairies
– Ice cream production
– Cheese production
– Bakeries
– Drinking water pretreatment
– Sewage treatment plants
– Slaughter houses
– Rendering plants
– Vegetable processing plants
– Canning
– Poultry processing
– Pet food production
– Seafood production
– Pulp & paper mills
– Aircraft maintenance
– Ballast water
– Bilge water
– Latex removal
– Prepared foods
– Tank & truck wash

Performance:CRT Series

Metals Removal Performance

Metal Reduction Precipitation Form
mg/L
Arsenic
– .005 Ferric hydroxide
Barium
– .50 Sulfate
Cadmium
– .05 Hydroxide
Copper
– .02-.07 Hydroxide
Mercury
– .001-.01 Alum. co precip
Nickel
– .12 Hydroxide
Selenium
– .05 Sulfide
Zinc
– .10 Hydroxide

Following the precipitation/flocculation stages if the particulate settle then a Slant Plate Clarifier is required. The Slant Plate Clarifier is the device of choice and will provide the following typical settling performance:

SPC discharge (mg/L)

TSS
– 5-20
Metals
-0.5-2.0

If the reacted solids or emulsions float or flotation is determined to be the proper separation device the DAF system will provide the following performance

DAF discharge (mg/L)

TSS/BOD
– 90-98%
O&G
– 90-99%


Pan America Environmental, Inc
2309 N. Ringwood Rd., Ste G, McHenry, IL 60050 USA
815.344.2960   •   panam@panamenv.com