By Rachel Schneider
At its Edgecumbe cream products plant, new sampler technology is playing an important role in helping New Zealand's Fonterra Dairy Cooperative further optimize process control and minimize product loss.
Sampling is a critically important task in the dairy industry. Since the 1970s, special emphasis has been given to wastewater sampling because tighter restrictions on wastewater discharge have placed greater accountability on the industry. Today, wastewater sampling is also highly important in loss reduction programs, to help maximize the bottom line. Fortunately, innovations in sampling technology have helped bring efficiencies to these programs and lessen the time and labor workload.
The Fonterra Dairy Cooperative in New Zealand is the country's largest company, with revenue representing more than 25 percent of total New Zealand exports. It is also the world's largest dairy exporter, processing about 15 billion liters of dairy products annually and exporting to more than 140 markets. Fonterra is owned by more than 10,000 supplier shareholders who together own about 3.8 million cows.
Fonterra's strong drive for innovation and efficiency has prompted loss monitoring technology and information systems to be installed at all of its manufacturing sites. The objective is to minimize the amount of milk solids going into wastewater from processing operations and equipment cleaning. Fonterra has developed specialized treatment and measurement techniques aimed at achieving best-in-class dairy production and processing, as well as wastewater management and beneficial reuse.
Determining Efficiencies, Reducing Losses
To monitor compliance to specific resource consent (discharge) conditions, determine efficiency and operation parameters before and after wastewater treatment, and to monitor trials for acceptance criteria during project commissioning, Fonterra conducts ongoing sampling programs to perform analysis and characterization of wastewater composition.
"We also perform sampling to gain measurement of product loss components to compare against process control targets," said Fonterra Senior Technologist Harold Prieditis. "From this data we initiate corrective action for loss minimization where applicable."
Prieditis said yield enhancement through loss reduction and continuous improvement is an important strategy for Fonterra.
"At a current value of about $5.20/kg milk solids, significant financial gains are possible by reducing losses by even a small amount," he said.
Sampling at Fonterra's many processing plants is conducted from process pipelines, or from wastewater sumps and drains, either inside or external to the plant.
"External wastewater drains are monitored daily by specialized permanent measurement systems," Prieditis said. "Sometimes external upstream contributory drains need to be surveyed for loss segregation purposes and a portable type of sampler may be used for this."
Equipped for All Sampling Methods
Sampling systems in use at Fonterra production sites include various types and models of air operated piston samplers, a range of solenoid valves, vacuum samplers, and several types of peristaltic samplers.
"There are even some innovative and very good low-technology solutions in sampling dairy wastewater," Prieditis said. "Due to the large range of sampling duties and the variety of conditions present, there is no single type of sampler that is best suited for every application. But portable and automatic samplers have a very important role in many of our wastewater survey and monitoring situations."
For example, Fonterra recently deployed a Hach Sigma SD900 Automatic Sampler (Hach SD900) for wastewater sampling at its Edgecumbe site. The site consists of three main manufacturing facilities: cream products, protein, and whey plants. Whole milk is received daily from nearby farms. The milk is then pasteurized and separated into skim milk and cream. The cream is directed to the cream products plant for manufacture into export butter and anhydrous milk fat. The new portable sampler is used at the cream products plant to quantify wastewater losses from various process start-up and shut-down stages.
By quantifying wastewater losses through the use of ongoing sampling, the amount of product losses in line flushes is minimized.
"The cream products plant required a portable sampler as part of its design for a new permanent wastewater loss monitoring system installed in August 2008," Prieditis said. "The update was necessary because the availability of spare parts and consumable items and the cost of imported components for our older types of samplers had become serious issues."
The Hach SD900 has enabled wastewater loss surveys and investigations to be performed more effectively in specific process improvement and end-of-pipe situations.
"An important requirement of a sampler for wastewater survey work in the dairy industry is to be able to segregate composite samples by hour of the day via a rotator or carousel function independent of time or flow paced sampling," Prieditis said. "This is so that composition of the wastewater in the 24x1L sample bottles can be aligned properly to the manufacturing processes involved."
"There are instances where for logistical and safety reasons, it's preferable to use a portable 12vdc sampler with flexibility of greater control options, and the Hach SD900 meets that criteria well," Prieditis said. "The sampler's ability to take a specified sample volume consistently from a variable flow and the apportionment of samples into 24x1L sample bottles are important features. Plus, the sampler's programmable integrated microprocessor makes it ideal for use in situations requiring more complex sampling capability."
Based on the positive experience with its initial SD900 Sampler, Fonterra has since specified 15 additional units.
About the Author:Rachel Schneider is the Flow & Sampling Product Manager at the Hach Company in Loveland, Colorado, USA.