Case Studies

Case History # 1: Vibratory, Metal Finishing Job shop

BACKGROUND: A very busy job shop has in business for over (18) years. Because business has been good, this company purchased a new and larger building next door – and they began to prepare the facility for moving the entire operation.

PROBLEM: Several permits were required, including a wastewater discharge permit. This new requirement was a jolt of reality. Approximately 10,000 gallons of vibratory fluids per day would have to meet discharge limits. An independent laboratory was commissioned to determine the characteristics of  the present streams: 

 The Following Are Highlights:

Characteristic

Existing Stream Discharge Limits
pH 10.3 6.0-9.0
TSS (total suspended solids) 23,150 ppm 300 ppm
TOC (oil & grease) 12,000 ppm 50 ppm
Pb (Lead) 22 ppm 0.01 ppm
Zn (Zinc) 180 ppm 4 ppm
Phenol 15 ppm 1 ppm

The management at this company realized their several dozen different clientele were capable of requiring deburring and finishing parts with a variety of incoming contaminants – namely stamping oils, straight oils, soluble oils, rust inhibitors, parts washing residue, etc. In short, a wide variety of chemistries and, the potential to dissolve metals in their process were "typical". Several waste hauling firms were contacted for haul-away quotes. Only licensed and reputable firms were invited to quote their services. Prices ranged from 18 cents per gallon + $75.00 an hour (min. 4 hours) trucking charge to $1.10 per gallon and no extra trucking charge. Management agreed that the most attractive bid was a flat fee of 30 cents per gallon. Even so, the prospect of 30 cents per gallon for 10,000 gallons per day equated to $3,000 per day! This new expense would be devastating to this company.

SOLUTION:  Wastewater Engineers, Inc. proposed an affordable system to handle the stream.

PHASE I: Create a closed-loop system to replace the pass-through method, which had been used previously. Because the vibratory process generates degraded media (various stone, plastic, ceramic, steel, etc.) the solids content was most challenging.

Various filtration techniques for sub-micron to larger sized solids particulate would be too costly and/or too slow. Wastewater Engineers, Inc. engineered a floor sump with a float-activated pump and a specially engineered baffled settling tank. Here, an oil skimmer was installed and a magnetic canister-type bag filter was employed. Thus, 95% of particulate volume and 75% of metal particulate could be settled and filtered respectively. A (75) GPM, float-activated pump was used on the settling unit to transfer treated fluid to a clean holding tank.

The entire system now has a total of 2,000 gallons. The above described mechanical methods are approximately 95% effective in maintaining vibe fluid cleanliness, and allowed for recycling.

Depending on the "dirt load" of incoming parts and metal burrs, the need to divert (200) gallons for chemical treatment ranges from (1) to (2) batches per day. To accomplish a treatment, Wastewater Engineers, Inc. provided a diverter valve, which allows filling of a RT-200-HO Reactor. The plant custodian is the operator. Wastewater Engineers, Inc. provided a pre-measured scoop and operator simply starts the turbine mixer, adds the scoop of powdered reactant and allows (5) minutes of mixing time. The mixer is then shut off and operator simply opens the drain valves. Operator attendance is approximately (10) minutes per (200) gallon batch. Processed fluid is automatically pumped from the RT Reactor to be recycled in the closed loop system.

This facility has reduced their tumbling/vibratory fluids ($385.00 per drum) from (4) drums per week to (30) gallons and has avoided the haul-away costs entirely. Samples of the sludge and treated fluids were sent to an independent lab for analysis. The sludge passed TCLP, and the fluid passed local sewer discharge standards.

"I was concerned about filling out waste manifests for a waste hauler and the possibility of future liability for a landfill clean-up. With this system, we are not required to haul away and we have no related paper work", says Terry Desch, Plant Manager.

"The cost to treat the system fluids is less than ½ the haul-away fees of our winning bidders charges and we are saving a substantial amount of money from our cleaning fluids purchases," says Plant Purchasing Agent.

Case History # 2: Fastener Manufacturer

BACKGROUND: A large (1.2 million sq. ft.) fastener manufacturer and steel coil treatment facility had a costly problem. This facility has a 150,000 gallon per day Zinc/Phosphate wastewater treatment system. Despite this capability, oils contamination from cold heading operations within the facility impose a solids and oil burden which the waste treatment system cannot process.

The oil spills and leakage from operating equipment is present on floors adjacent to production machines. Riding floor scrubbers are in constant operation, (8) hours per shift, (3) shifts per day, (6) days per week. In addition, each of (200) cold heading machine operators maintain safe & clean conditions in work areas using mop & bucket w/cleaner. Total dirty floor cleaner waste is over (1,200) gallons per day.

PROBLEM: This facility had been using a (7,000) gal. Capacity floor pit to accumulate cleaner waste. A liquid waste hauling firm had been contracted to pickup and dispose of this material, however; solid debris such as sand, dirt, zinc-sterate, scrap metal particulate, etc., was left behind. Up to 25% solids began to accumulate, thus; a special arrangement with the hauling service added solids removal to the pick up service, resulting in a 40 cents per gallon charge. Wastewater Engineers, Inc. was contracted and requested to propose cost savings. Investigation and engineering studies indicated an opportunity to reduce costs and to provide the customer with additional savings via recycling.

SOLUTION:  Wastewater Engineers, Inc. proposed an affordable  system to handle the stream.

PHASE I: Gross Contaminants Removal. W.E., Inc. designed and built a special receiving box. This unit features a perforated (removable) screen, which captures larger debris such as papers, broken pallet wood chips, miscellaneous fasteners, scrap metals and general debris. The system operator simply dumps accumulations into trash barrels. A series of baffles in the receiving box promotes dirt settling. A pump transfers fluids from the receiving box, through a canister type bag filter and into a (2000) gallon capacity holding tank. The holding tank provides storage and retention time for oils to precipitate to the surface where a belt-type oil skimmer removes gross oils.

PHASE II: Polish Fluids Via Batch Treatment. The riding floor scrubber operator was assigned the responsibility of operating the treatment system. Upon demand, operator "starts" a transfer pump to fill an RT reactor unit. W.E., Inc. provided float & level controls and a "mix tank filled" indicator light on the RT control panel. This allows the operator freedom to perform other duties while the RT unit is filling. The Operator pushes "start" button on RT unit’s turbine mixer, adds WE reactant and allows (5) minutes of mixing and reaction time. The WE reactant initiates a process of precipitation and agglomeration of contaminants, and; produces a large "floc" which results in a complete separation and encapsulation of contaminants. The rapid settling of the "floc" allows the operator to open drain/filter valves after only (1) minute automated, operator is required to attend the reaction/treatment batch process for less than (10) minutes per batch.

Fluids are automatically pumped via float activated pump from the RT unit to a clean (recycling) tank. Approximately 90% of the active soap ingredients remain intact after the Wastewater Engineers Inc. process, thus; a reduction in floor cleaning chemical can be realized.

RESULTS: Savings in Treating Vs Haul Away This facility has saved over 60% Vs haul away and reduced chemical floor cleaning expense by 90%.

COST SAVINGS

Hauling:

Volume/year Hauling cost @ $0.40/gallon Treatment cost @$0.15/gallon
360,000 gallon $144,000 $54,000

Cleaner (soap):

Before Installation of Wastewater Engineers, Inc. system:

Cost of cleaner Gallons/week Cost/year
$3.79 350 $66,325.00

After installation of Wastewater Engineers, Inc. system.

Cost of cleaner Gallons/week Cost/year
$3.79 50 $9,475.00

Savings Summary:

Hauling Cost

$144,000

Treatment cost

$54,000

Savings

$90,000

Cleaner cost before system $66,375
Cleaner cost after system $9,475
Savings $56,900

Total Savings:                              $146,850

Additional Information:

A 200 gallon capacity unit was initially sold making the complete "hardware" cost of all items at $31,450. Payback (ROI) was (3) months. System was installed in Jan. 5, 1991. Because of added daily volumes from parts washing fluids and vibratory fluids (both streams have high oils & solids), an RT 500 HO Unit was installed in March, 1995. The original (200) gallon unit treated (6) batches/day, (6) days/wk for (3) years. Approx. $50. For repair parts (float valve) was total maintenance cost over the (3) years of service. The original RT 200 was moved to another plant and is still in service. This business has purchased additional systems  for (4) additional plants, (5) turn-key systems in all. Floor cleaner effluent was tested for sewer discharge standards – all characteristics were within discharge limits. Most critical were zinc sterate, oils & solids. Sludge passed original TCLP and each year for (3) additional years.
This business has sealed all floor drains and is a "zero discharge" facility. All water-based processed fluids are now being recycled