Mexico's largest chicken processing plant was experiencing high levels of BOD discharge into the local river because their two sludge lagoons were full of high percentage solids sludge. The plant was expanding operations and had no place to store the additional sludge that would be generated, nor did it have any onsite means of removal and dewatering.
The problem was compounded because the excess BOD discharge exceeded their operating permit limits and local environmental regulators were requiring immediate action or the plant would face an imposed shutdown.
TenCate develops and produces materials that function to increase performance, reduce cost, and deliver measurable results by working with our customers to provide advanced solutions. For this situation, Geotube dewatering technology proved to be the solution.
The plant environmental management team contacted the TenCate Geotube distributor in Mexico City, GyG, to ask for a solution that could be implemented almost immediately and less expensively than the traditional mobile mechanical dewatering or pump and haul lagoon clean out methods. GyG reviewed the challenge and presented the plant with a strategy utilizing Geotube£ dewatering technology.
Dewatering with Geotube technology is a three-step process. In the confinement stage, the Geotube container is filled with dredged waste materials. The Geotube2 container's unique fabric confines the fine grains of the material. In the dewatering phase, excess water simply drains from the Geotube£ container. The decanted water is often of a quality that can be reused or returned for processing or to native waterways without additional treatment.
In the final phase, consolidation, the solids continue to density due to desiccation as residual water vapor escapes through the fabric. Volume reduction can be as high as 90 percent.
After an initial site visit, GyG and TenCate Geotube recommended that the plant convert the onsite baseball field to a Geotube dewatering cell by placing an impermeable liner on the field surface over which a three-dimensional net to facilitate drainage could be placed. Then the first of two layers of 90' circumference GT 500 Geotube2 units could be unrolled in the cell.
After filling and dewatering, a second layer of Geotube8 units could be installed if necessary. The sludge could be pumped from the lagoons by an 8' auger head dredge to the Geotube dewatering system through a manifold system. It was recommended that a cationic polymer be utilized to flocculate the sludge and accelerate dewatering and to improve the quality of the effluent. This polymer could be blended on site in 500-gallon mix tanks and injected inline.
Over a period of 90 days, more than 25,800 m3 of 12% solids were removed from the two onsite lagoons by the 8' auger head dredge and pumped into seven 90' circumference x 217' long and five 90' circumference x 188' long GT 500 Geotube units for dewatering. The entire dredging and dewatering functions were conducted without a single interruption of plant operations.
The dredge bulked the sludge to 5% solids for pumping, which resulted in more than 62,000 m3 being pumped through the Geotube dewatering system. Effluent from the Geotube units was clear with more than 95% of the solids being removed. The two onsite lagoons have been restored to operating levels and discharge into the adjacent river are below BOD permitted limits. The sludge is continuing to dewater in the Geotube2 units and will be made available to local farmers for fertilizer.