Land Application/Midwest: From Crisis to Land Application Solution

Challenge:
In 1992 city officials in Grand Rapids, MI, identified the need for a liquid land application program for 16,500 dry tons of biosolids generated annually. The city already had a permanent treatment system in which treated biosolids were vacuum-filtered and incinerated. However, it was costly and prone to mechanical failure over time. As an interim measure, Houston-based Synagro developed an economical beneficial use program to manage about one-third of Grand Rapids’ biosolids generation through land application.

Then, in spring 1998, the city wastewater treatment plant experienced a catastrophic breakdown of its permanent treatment system, losing its backup stabilization process.

Solution:
Synagro quickly proposed short-term, around-the-clock biosolids management services for 100% of Grand Rapid’s biosolids. It installed a mobile belt filter press and ancillary conveyance equipment to dewater the unstabilized biosolids and provide filter press cake for landfill disposal. With the emergency under control, a decision was made to implement a long-term solution for the city.

While continuing emergency services, the company installed three permanent presses, including all pumps, conveyance equipment, a polymer system and truck load-out, in a small existing footprint. Dewatering and landfill services for the entire production of biosolids were provided with no downtime. Once the emergency was abated, the Grand Rapids dewatering team moved to steady-state status, operating 24 hours a day, six days a week.

Result:
In 2001 Grand Rapids bid out services to dewater and landfill 75% of its biosolids and manage the remaining 25% through land application. Synagro responded with a proposal for cost-effective, full-service dewatering and combined landfill and land-application services. The city awarded the company a three-year contract to retrofit dewatering operations by adding new centrifuges, conveyance equipment, an odor-control system, and a lime-stabilization system. The company converts biosolids into dewatered cake and land-applies the Class B biosolids on area farmland.

Synagro anticipates that through the use of the centrifuges, the dewatered cake solids will increase to 28% of total solids, thereby reducing the tonnage to be landfilled and reducing operating hours to one shift a day.

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