Tanning Facility Wastewater Treatment: Analysis of Physical-Chemical and Reverse Osmosis Methods

The process of leather tanning produces harmful chemical and organic pollutants. This study explored physical and chemical treatment methods to both effectively and efficiently treat the tanning wastewater effluent. Multiple wastewater streams representative of various stages in the tanning and wastewater treatment processes were initially characterized and subsequently treated. The treatment processes that were studied included chemical coagulation and flocculation, adsorption, granular filtration, and reverse osmosis. Through a series of jar test experiments, multiple industry-grade polymers as chemical coagulants greatly reduced chromium concentrations and turbidity levels. Adsorption experiments were also conducted on the wastewater streams to study chromium and nitrogen removal efficiency with titanium dioxide oxide nanoparticles and activated carbon. Poor adsorption of chromium occurred for both the nanoparticles and activated carbon. Reverse osmosis was studied to determine the effectiveness of removing contaminants of typical concern for the tanning facility. The reverse osmosis tests also determined the ability to recycle the complex wastewater effluent from the contaminant-laden tanning processes. Results indicated that reverse osmosis treatment was not only a viable treatment alternative, but could be used to adequately treat the wastewater to match conditions similar to sourced well-drawn groundwater. Of the wastewater treatment methods explored, the use of polymers as coagulants proved to be the most successful at chromium reduction and turbidity improvement as a traditional method. As an alternative method, the reverse osmosis prototype proved most successful due to the production of high-quality product. The application of membrane filtration may potentially allow for future reuse within the tanning processes.