The potential environmental impact of tanning activity is significant since the major portion (almost 70-80 %) of transformation of raw hides/skins into finished products occurs in water phase (average consumption of water for tanning processes is between 25 – 30 m3 per ton of raw material processed), so it is evident that the main load of pollutants occur within the wastewater
The Reptile Tannery of Louisiana (RTL) facility processes imported reptile skins in a tanning process that results in a high-strength wastewater heavy in organic loadings. The current wastewater treatment system must be manually operated and monitored regularly by RTL staff to ensure effluent quality objectives are met. However, the limitations in a system that includes equipment past its useful life or needs continuous monitoring or repair results in effluent that is out of compliance with Louisiana Utility Service (LUS) regulations.
In 2014, RTL requested to design and supply a new wastewater treatment facility using Napier-Reid’s BIO-BATCH™ Sequencing Batch Reactor (SBR) technology for the Reptile Tannery of Louisiana in Lafayette to meet or exceed LUS industrial discharge requirements for BOD5, TSS, COD, chromium, and pH levels.
The design flow for RTL SBR system is 150 m3/day, which will accommodate future production expansion.
There are three types of wastewater in this system: Sulfide Stream, Chrome Liquor and Pillow Stream. Sulfide stream and pillow stream are merged and sent to the primary tank. Prior to entering the primary tank, lime is dosed to adjust the pH, ferric chloride is dosed to react with sulfide if required, and finally, alum is dosed to form floc. After settling, clarified flow will be introduced to and alternated between two SBR reactors. After biological treatment, decanted water will discharge to Louisiana Utility Service collection system. Waste Activated Sludge (WAS) from SBR system will be pumped to the existing sludge holding tank. Filter press is provided for dewatering of the WAS sludge to achieve 25% dry sludge cake for carted away disposal.