The Millbury, Mass., pumping stations are part of a regionalized consortium of eight communities that discharge their wastewater to the Upper Blackstone Water Pollution Abatement District for treatment. The 56-million-gal-per-day facility sits at the headwaters of the Blackstone River, once considered one of the most polluted river ways in the country. As a result of plant upgrades and projects, the water quality was considerably improved and the river will be swimmable by 2015.
"We originally were a secondary trickling filter treatment plant, but were decommissioned after the town of Millbury joined the district," explained Plant Superintendent Bradford Lange. "From then on, we were responsible for the maintenance and operation of sixteen pumping stations."
"In 2005, we began a major upgrade of old equipment, including a Worthington comminutor that needed to be taken out of service," Lange said. “It was very important to have an inline unit that could efficiently grind and screen wastewater solids so they could be easily processed by the pumps.”
“On the recommendation of our engineer, we installed a Dimminutor T20 Channel Disintegrator  ,” Lange said. “The unit has an extended shaft and this was a major consideration in our selection. We are located in a flood plain and we needed that shaft to keep the motor up above any flooding that could occur.”
According to Lange, purchasing the Dimminutor  was a wise decision. “The unit has so many great features. It easily chops up everything in its path: rocks, sticks, you name it. In case of a jam, there is a reliable reverse mode. Because of its open design, the unit has a lot less headloss. It takes in as much water as it can get, resulting in a higher velocity of flow. This higher flow speeds the entire process up for us.”
“We recently bought another Dimminutor T20. The two units are placed side by side in a channel and are rotated monthly,” Lange said. “The original unit has never been taken out of service. It works as well four years later as the day it was installed. The Dimminutor is a fine, rugged piece of equipment. When you're in the field, you want something dependable. We're very satisfied.”
"Incidentally," Lange concluded, “shortly after we installed the first unit in 2005, we experienced a tremendous flood, the kind that occurs once in a hundred and twenty five years. We were literally underwater for two days, but the Dimminutor kept right on going."
The Dimminutor offers effective, automatic screening and disintegrating of wastewater solids in straight-through channels and wet wells. This powerful unit reduces plastics, wood, rags and other solids to fine bits, enhancing plant operation and improving the reliability of pumps and other downstream equipment.
The Dimminutor employs a smooth, continuously rotating design with high torque. As its three bidirectional rotary cutters intermesh at close clearance with stationary cutters, solids are finely reduced to a size small enough to pass through a sizing screen. With no gaps or openings between the screen and cutters, output is controlled and complete reduction assured.
The Dimminutor has an intrinsically open design to handle high flow rates with low headloss. This unit is extremely easy to maintain and features individually replaceable cutters, oil lubrication and a simple rotary design requiring no auxiliary diverter screens. A unique, cantilevered design eliminates seals or bearings near the gritty channel floor. Every component of the unit is constructed for precision and long life.