Not By Flocculant Alone – How Dissolved Air Solves A Paper Recycling Problem

Inquire about the Keystec pump: Call Dave Keys at 714-924-4422.

My Brother Dan and I went to visit a paper company a couple of weeks ago, here in the Los Angeles area. In East LA and Commerce there are miles and miles of industries that run various processes and you can imagine that recycling wastewater is of premium concern both for the savings of water, and the cost of disposing of waste materials.

Problem Solved with DAF Airwhip Technology

Enter the paper company. They had done some online research and called on Keystec to solve the problem that had arisen from trying to solve another problem.

The paper company produces recycled, post-consumer content cardboard, the sort that is used to package up your typical products from dry pasta to cardboard bases for shrink-wrapped goods. In an effort to recover more of the ink, clay, ash and debris from the water used in the paper making process, they had made adjustments to a chemical flocculant in the water. This seemed to work great- lots of material was floating to the surface in the processing tanks, but before very long at all, the operators realized that the flocculant was the consistency of chocolate mousse and there was lots of it. So much that it spilled over the collection tanks and processing byproduct ran onto the basement and everywhere.

It left lots of clay in the tanks too. A big mess.

We arrived on a Tuesday morning and met with the folks there and had a look at the so called DAF they were operating. It was using an old style cavitation pump, sucking air into the pump and spinning it out via centrifugal force, producing some fairly large sized bubbles. In essence, instead of creating a flocculant, they were creating big bubbles with coagulant clinging to it.

Oops! We’ve got it a little backwards here. True dissolved air flotation creates microscopic bubbles and they collect around relatively large flocculant particles and float them to the surface where the flocculant has the consistency of oatmeal, not chocolate mousse! They needed the proper three stage process of coagulation, flocculation and dissolved air flotation. Their pump wasn’t going to do the job with the single flocculation turned coagulation stage they were using, neither would it do much with a better flocculation with a two stage process because the bubbles were like beach balls compared to what’s needed for dissolved air flotation.

We recommended the Keystec Airwhip pump for its perfect application to this problem and its longevity compared to standard DAF pumps.

Soon this company will be returning much of this paper by-product back to the new product and returning clear water to their system.

Result? Savings from reduced downtime, savings from reduced sewage fees and savings from reduced disposal of paper byproducts that should be re-integrated with new product.

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New and used recycling equipment

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Dissolved Air Flotation Strategy for Oil Spill – Water Oxygen Replenishment Cleanup

Dissolved Air Flotation offers a double problem solving strategy in cleanup and removal of oil from the BP gulf oil spill. While centrifuges such as those designed by Kevin Costner, separate suspended oil, a more difficult “byproduct” emerges in the process. “Stick” water, the kind usually derived from fish processing. The resulting emulsified oil/water solution is typically separated using DAF – Dissolved Air Flotation equipment onsite at food processing plants.

Complicating the cleanup of oil contaminated water in the gulf the process that nature itself has already begun. Microbes are consuming the oil in a feeding frenzy and multiplying to match the supply. This new population, in turn, creates proteins in their waste and simultaneously depletes available oxygen in the water. Fish are reportedly leaving en-masse for water with enough oxygen to sustain life. Fish which normally avoid each other or hunt each other from sharks to marlin are swimming in virtual refugee convoys.

Dissolved Air Flotation can deal with the emulsified oil in the new dead zones, the proteins and replenish oxygen all at once. The Keystec Air Whip pump, installed in custom Dissolved Air Flotation equipment is the core of a long lasting super air-injecting and waste collecting system that is equipped to speed shallow water marsh recovery.

Dissolved Air Flotation | Experience

The right DAF – Dissolved Air Flotation – for your application.

P-TEC offers equipment and system designs to meet the exact nature of each of our clients’ needs.  Whether your flow is 5 GPM or 3000 GPM, we have a custom solution for your need. Custom Built dissolved air flotation to fit your exact application based on extensive expert experience in DAF design and innovation.  From grease removal in a restaurant to water recovery in a paper mill, we can offer the solutions that will solve your problems.  We have experience in:

Dissolved Air Flotation – Applications and Limitations in Wastewater Treatment

Dissolved Air Flotation is widely used in Wastewater Treatment as well as in less traditional applications such as:

•   drinking water clarification and color removal
•   Algae removal
•   By-product recovery  (i.e. metals, etc.)
•   Dissimilar solids separation

Within Wastewater Treatment, DAF application can be divided into
•   Primary Treatment
•   Secondary Treatment
•   Tertiary Treatment

In all cases, DAF (dissolved air flotation) is used to separate fine solids (any constituents that are not dissolved) by flotation, assisted by the attachment of microscopic bubbles.  Often, solids that would normally settle are forced to the surface for removal through the attachment of those fine bubbles.

DAF is used in a wide range of situations where the suspended material  can be as little as 20 mg/l (as in algae or color removal) to tens of thousands of mg/l as in rendering or some petro-chemical oil/water separation situations.  Each case must be evaluated for size, flow, and chemical requirements.

To further complicate the issue, the general term, DAF, no longer covers all the approaches to separating solids with microscopic bubbles.  Other similar technologies that are frequently referred to as DAF are:

•   CAF (cavitation air flotation)
-Bubbles produced by a spinning disk without pressure
•   BAF (bubble air flotation)
-Bubbles produced by blowing air through a micro-filter into the water
•   SAF (saponification air flotation)
-Bubbles produced with the aid of a surfactant for more aggressive attachment
•   EAF (entrained air flotation)
-Bubbles produced with relatively low pressure and high shear, entrained in the water

Dissolved Air Flotation

DAF Pumps

DAF Design

Dissolved Air Flotation | Can DAF Solve The Ice Cream Problem?

Can DAF (dissolved air flotation) solve the wastewater problem for ice cream plants? Success is obtained in Dairy Pilot testing.

Dissolved air flotation is an effective application for removal of BOD, suspended solids, oil and grease from wastewater used in Ice Cream production and other Dairy processes. P-TEC ran a pilot test study for this application while determining the coagulant and dosing levels for specific reclamation.

In this test, plant effluent was delivered to a 1100 gallon coagulation pH buffer tank. The coagulated, pH adjusted water then was introduced to P-TEC Model MD-2442 20 GPM Dissolved Air Flotation (DAF) System with an integrated flocculator. Here, flocculant was dosed.

Each test was preceded by jar testing to determine the usual needed chemical dosing rate. During each test, monitoring included, dosing, flow rate, aeration, etc. Hourly samples of influent and effluent were taken in 500ml amounts as well as sludge samples to to estimate produced volume.

Results:

DAF Pilot Test Results - Dissolved Air Flotation

Dissolved Air Flotation – DAF • Algae Removal Effective?

Dissolved Air Flotation (DAF) has proven very effective for algae removal.  (Full Algae TSS Removal article)

DAF evaluation was prompted by a state imposed limit of 45 mg/l TSS to discharge into a river. The bulk of the residual TSS in the effluent was daphnia “water fleas” that was visible to the eye.

Contact P-TEC at 800-450-0398 for more information on effective use of DAF Systems.

DAF evaluation to solve problems with existing sand filters being plugged with algae floc.