Peristaltic metering assists with arsenic removal in wells

Problem:

The drinking water sources in the town of Mammoth Lakes in northeast California consist of nine wells and water from Lake Mary. Arsenic is present in the well water, and the Mammoth Community Water District developed two groundwater treatment stations and one surface water station to combat it. Sodium hypochlorite and ferric chloride are used in the multistep arsenic-removal process. Initially, the well stations used solenoid type pumps, but the off-gassing nature of the sodium hypochlorite created vapor lock in the pumps.

Solution:

The district installed Proseries-M M-3 peristaltic metering pumps from Blue-White Industries to assist in treatment. The pumps are capable of feed rates to 33.3 gph, with a 10,000-1 turndown ratio. The maximum pressure rating is 125 psi.

Result: 

The peristaltic design allowed the excess gas to be pumped through the tubing while maintaining smooth, accurate and constant flow with no potential for vapor lock. 714-893-8529; www.blue-white.com

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Aerators and mixers enable cost savings, reduce biosolids buildup

Problem:

The town of Monroeville, Alabama, faced aeration and mixing issues, sludge buildup in one of its wastewater lagoons, and power bills of $12,500 per month after a major employer relocated its garment manufacturing facility. The company had generated about 90% of the wastewater entering the lagoon, and its fees covered 90% of the operation and maintenance cost, which included $1,500 per month for aerator maintenance. The lagoon was 80% full of biosolids, and the estimated cost to dredge was over $1.6 million. The lagoon had to remain operational and the town needed to reduce costs.

Solution:

DO2E Wastewater Treatment installed two 5 hp high-volume floating aerators and two 3 hp floating mixers.

Results: 

In four years of operation, the equipment saved the town some $513,000 in electricity and $72,000 in maintenance while reducing biosolids buildup by 90%. 850-698-6805; www.do2e.com

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Facility employs peristaltic dosing pumps to apply sodium hypochlorite

Problem:

A wastewater facility in Nashua, New Hampshire, needed a system to control the dosing of sodium hypochlorite for disinfection, and peristaltic metering tube pumps to deliver pumping of sodium bisulfite and sodium hypochlorite.

Solution:

The facility purchased two Flowrox LPP-D25 peristaltic dosing hose pumps with a Halar coating for protection against the aggressive sodium hypochlorite in case of a hose failure. They included hose leak detection to shut the pump down in case of hose failure, and integral variable-speed motors with 4-20mA input for control. The pumps combine intelligence with suitable turndown. They will not experience vacuum degassing in summer.

Result: 

The city has been satisfied with the pumps’ performance. 410-636-2250; www.flowrox.com

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Bypass system helps plant expand

Problem:

To stay in compliance with state EPA requirements, the Kiski Valley Water Pollution Control Authority in Pennsylvania had to double the capacity of one of its plants from 15 to 31 mgd. As part of the expansion, the authority had to replace its influent pump station once construction was completed.

Solution:

With help from an engineering contractor and Xylem, the authority built a bypass pumping system to handle the flow during construction. Xylem in- stalled five Flygt NS 3301 electric submersible pumps as a rental. Since the plant did not have enough power to run the pumps, each one ran off of a 104-kW Godwin generator with a 100 hp Godwin variable-frequency drive to handle the variations in flow. Two 24-inch Xylem MJK flowmeters were also installed, in addition to level transducers in the wet well. At the core of the project was a SCADA system to receive data from level transducers in the wet well and trigger the generators and start the pumps at predetermined levels. The VFDs then controlled pump speed to maintain appropriate system flow. The pumps, generators and VFDs worked sequentially. For optimal efficiency and to save energy and diesel fuel costs, each pump activated only when increased flows called for pump activity.

Result: 

Over the life of the project, the technology saved thousands of dollars through energy efficiency. The real-time, advanced remote monitoring and control technology also provided authority personnel and customers with peace of mind. 800-247-8674; www.xylem.com/dewatering

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Chopper pump helps stop clogging at lift station

Problem:

A Texas wastewater treatment plant’s main lift station needed better mixing to break up persistent grease and scum layers. Three small pumps could no longer cope, and objects such as mopheads caused blockages. The maintenance team was always on call. In some cases, a vacuum truck had to be called at significant cost.

Solution:

The municipality chose a Gator series submersible chopper pump from Landia, developed to eliminate lift station clogging caused by wet wipes and other debris. It has a hardened steel knife system at its inlet that continuously macerates and mixes solids. Its open impeller enables it to pump even high-viscosity flows.

Result: 

The duty pumps are now better protected. The chopper pump picks up the solids from the bottom of the lift station and breaks them up so that they do not accumulate and cause clogging. 919-466-0603; www.landiainc.com

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Reactor system enables power plant to increase effluent oxygen level

Problem:

To protect its equipment from corrosion, a Texas power plant removed oxygen from its process and cooling water before use. But releasing water with low dissolved oxygen into a watershed can harm the aquatic environment and violate government regulations. The facility pumps 1.5 to 3 mgd of cooling tower effluent 2 miles to a settling pond and another 0.75 mile to a nearby creek. Regulations require 5 mg/L minimum DO; the plant saw levels from 0 to 3 mg/L. 

Solution:

Mazzei Injector’s sidestream venturi injection and Pipeline Flash Reactor system solved the problem. It is installed on a 30-square-foot skid at the discharge and requires minimal maintenance — the only equipment with moving parts is the small sidestream pump. The boosted sidestream passes through an injector and then is mixed back into the main flow through the pipeline flash reactor.  

Result: 

Weekly sampling showed a rise in DO to the 8 mg/L requested by the plant managers. 661-363-6500; www.mazzei.net

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Switch-rated plugs significantly cut pump replacement and maintenance downtime

Problem:

During construction of a wastewater treatment plant in Watertown, Wisconsin, submersible pumps for effluent were hard-wired. Soon after operations began, one pump had to be replaced. That took the maintenance crew almost a full day; most of the time was spent disconnecting the electrical connections and rewiring the new one.

Solution:

MELTRIC Switch-Rated plugs and receptacles, which combine the safety and functionality of a disconnect switch with the convenience of a plug and receptacle, were installed on all the pumps. Because they are Type 4X/IP69K/3R watertight, the plugs and receptacles are suitable for connecting submersible pumps indoors and outdoors. Spring-loaded, silver-nickel, butt-style contacts provide consistent electrical performance. The contacts resist wear, corrosion and oxidation.

Result: 

The plug-and-play functionality significantly reduced pump replacement time by eliminating unwiring/rewiring. Because of the safety of the devices, maintenance technicians can easily replace or service the pumps without needing an electrician or using personal protective equipment. 800-433-7642; www.meltric.com

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Progressive cavity pump replaces piston pump, lowering maintenance costs

Problem:

A wastewater treatment plant near Lexington, Kentucky, had frequent maintenance with piston pumps used to convey sewage. Replacement parts and maintenance hours were becoming costly.

Solution:

SEEPEX provided BN progressive cavity pumps with Smart Conveying Technology for ease of maintenance without piping removal. SCT includes stator retensioning, which provides longer intervals between stator replacements. These features keep costs and personnel time to a minimum.

Result: 

“Compared to the previous piston pumps, Smart Conveying Technology makes maintenance and repair work significantly easier,” says Mike Smith, maintenance supervisor. “The spare parts are much more cost-effective and downtime constitutes a fraction of previous values. Pumps with SCT can be serviced in a fraction of the time without having to dismantle them.” 937-864-7150; www.seepex.com   

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Plant updates biosolids piston pump

Problem:

The Noman M. Cole Jr. Pollution Control Plant in Lorton, Virginia, installed four Schwing Bioset sliding-frame intermediate storage silos and KSP 45 piston pumps to store and pump biosolids. The units have been in service for 15 years pumping centrifuge-dewatered biosolids into an incinerator. The original equipment was sized for growth that has not materialized; the plant struggled with turndown while heating up the incinerator after a shutdown. The plant would overcome this issue by artificially starving the pumps or by cycling them on and off during that condition.

Solution:

The KSP 45 piston pumps are to be replaced with smaller Schwing Bioset KSP 25 piston pumps that have the same footprint, operate from the same power unit, and have the same operational features, including sludge flow measuring for U.S. EPA reporting, while providing the turndown needed to resolve incinerator restart issues.

Result: 

The new equipment is to be delivered in the first half of 2020 and is expected to provide the same reliability and longevity as the existing pumps. 715-247-3433; www.schwingbioset.com