“They were on the job, 24/7, and didn’t require overtime pay.” That’s Jarrod Shotts’ to-the-point assessment of Sigma 900 Series Portable Autosamplers. “And they’ll do the same for several future projects, including an upcoming distribution system profiling study,” he added.

Shotts, the Special Projects Coordinator for the Purification Department of the Birmingham, AL, Water Works Board, put Sigma portable autosamplers to work in a recent study examining sedimentation loading to raw water storage for the Shades Mountain Filter Plant. Three autosamplers, positioned around a basin at points receiving source water from the nearby Cahaba River, captured samples that were analyzed for total suspended solids (TSS). The TSS loading data gave engineers feasibility information for possible tank replacements in the existing receiving basin.

Samplers replace boats
Through the months of January and February, 2004, the tireless automated samplers consistently collected 200 mL samples every six hours, 24 hours a day. “They did the work of a small crew,” said Shotts. “Two of our sampler inlets were anchored under water at the point where pipes delivered the river water to the basin. Without the samplers, we would need two guys out in a boat, every six hours, to collect from these points, in who-knows-what weather. The samplers provided dependable, safe collection without the need for extra staff.

“Programming of the units was simple, then we just walked away and let them do what would have otherwise equated to expensive overtime labor.” He added that technicians simply harvested 12 sample bottles from each portable autosampler every other day, replacing them with empty bottles for the next sampling period.

Flexibility for other projects
Shotts explained the Birmingham Water Works Purification Department has been doing business with Hach for years. The 80-MGD Shades Mountain Filter Plant relies on 50 Hach process turbidimeters to monitor enhanced-coagulation filtration with dual-media filters. “Comparing sampler value with other products, and knowing Hach’s reputation, we chose the Sigma samplers,” he said.

“They offer flexibility for use in other projects. They accept a variety of sample containers, can collect composites, and are easily programmed for various routines.”

Shotts will use the Sigma Portable Samplers in an upcoming distribution system evaluation, collect-
ing samples for profiling of aluminum, coagulant, iron, and other key parameters 3900 miles of water system – again, saving significant labor costs. “In the saved labor, the autosamplers have probably already paid for themselves,” he said, “and we’re certainly not done with them yet.”

Superintendent Dayne Yates at The City of Cornelia, GA, Water Pollution Control Plant is convinced the Hach LDO® Probe is the technology of choice at his plant, now and in the future. “The LDO unit is a great meter; I’m really pleased with it,” he emphasized.

Measuring dissolved oxygen (DO) is a significant task at this tertiary-treatment, plug-flow activated sludge plant located in northeast Georgia, about 90 miles northeast of Atlanta in Habersham County. The Biological Oxygen Demand (BOD) levels in plant influent range from 300 to 500 mg/L, depending on rainfall dilution. The DO at the aeration basin inlet typically ranges from 0.2 to 0.5 mg/L. An extended aeration process allows operators to adjust aeration for better ammonia removal, according to Yates.

LDO units replace ‘temperamental’ DO meters
Four different people – two treatment operators, the plant lab technician, and sometimes Yates himself – check DO about 9 am and 2 pm at aeration inlet and outlet daily to monitor oxygen available to, and consumed by, the processing microorganisms. DO values typically decrease in the afternoon, when attendants manually adjust blowers to maintain a DO concentration of 4.9 to 6.2 mg/L as the stream enters secondary settling.

The staff previously used three units of a membrane-type DO meter. “They’re temperamental. Just like people, they don’t respond similarly. Each of those meters performs differently.”

Time and ease-of-use benefits describe LDO
Yates enumerated the reasons he prefers the Portable Hach LDO Meter: no calibration or warm-up required, compared to the 30-40 minutes needed to prepare the membrane-type meter; the ease of use; quick response – no more than 1-2 minutes; and stable reading.

He also appreciates data logging for subsequent recall. “All our measurements are made on site, at the basins and occasionally during pretreatment monitoring, and this meter makes DO measurement one less thing to worry about doing.”

Lois Holden, the facility’s Laboratory Technician who has used the membrane-type dissolved oxygen meters since she started work there 12 years ago, agreed, “It takes so much less time than the old meter.”

Readings that can be trusted
Because the Hach LDO Meter responds quickly and is immune to the measurement error often associated with fouling of traditional sensors, it

Laboratory Technician Lois Holden uses the Portable Hach LDO® Meter at The City of Cornelia, GA, Water Pollution Control Plant. The 3.75-MGD facility has eight aeration cells that can be used in parallel or in series to adjust aeration for variable flow and load.

can be relied on for accurate readings. Yates explained how effluent from the facility’s contact chamber is sent down a tortuous spillway of multiple steps for thorough aeration prior to discharge. “Here, we are targeting saturation, and I would expect higher readings. When I see the Hach LDO Meter read slightly higher than the membrane-type meter at this discharge point – usually within 0.3 mg/L of the old meter – I believe the higher values provided by the LDO meter are correct.”

LDO is technique of the future
Expecting restrictions in permitted phosphorus concentrations, Yates is already discussing a facility upgrade that would include use of chemical precipitation and possibly anoxic treatment for augmented phosphorus removal. “If we go to the use of anoxic zones, we’ll want continuous DO monitoring to carefully control oxygen availability in each cell. I’ll definitely request an on-line LDO Probe,” he affirmed.

Next-generation spectrophotometer available soon
 
More than a laboratory instrument,
it’s an analysis system!

The new DR/5000 UV-Vis Spectrophotometer automatically reads Hach barcoded TNT Plus™ reagent vials (see below), automatically recognizes the method needed, and automatically determines the reagent blank.

This instrument-reagent integration also yields 10-fold measurement and averaging – all to reduce reagent consumption and testing time while improving testing accuracy and productivity in any laboratory.

And, the DR/5000 Spectrophotometer incorporates a deuterium and tungsten halogen lamp for unparalleled optical stability and drift-free measurement typical of more expensive photometers. This flexible system uses a single cell adapter that holds the five most common sample vial types, a multiple-cell carousel adapter, pour-thru cell adapter, 13- and 16-mm cell compartment, and sipper module.

The DR 5000/Spectrophotometer includes the widest range of water analysis methods available in a single instrument, targeting water and wastewater treatment and process water control for nearly any industrial application. And a user-friendly touch screen puts you in complete control.

The Hach Field Service Partnership Program instituted at the Seminole County (Fla.) Water and Sewer Division of the Environmental Services Department is yielding operational and administrative benefits. Here’s another: the utility’s state inspector is satisfied, too.

Jack Cheney, Wastewater Operations Supervisor, reports the division adopted the service support plan in March 2004. “Our maintenance superintendent called it a ‘nobrainer.’ The Hach service manager visits our site and takes care of all scheduled maintenance and calibrations. He repairs analyzers that suffer power surges from lightning strikes – we have some spare analyzers on hand to cover us.

“A big benefit is that our DEP inspector is pleased to see instrument certification forms – completed, dated, and signed by the factory representative – on hand when he visits.

“And this plan suits our budgetary strategy of relying on contracting services when appropriate. The Service Partnership helps us contain O&M costs.”

Cheney indicated the division also relies on the Hach Scheduled Inventory Reagent Replacement (SIRR) Plan to receive fresh instrument reagents on a prearranged schedule. “The way I have it set up, we get the reagent about two weeks before we use it. And we get to take advantage of the quantity discount.