The strong momentum experienced in 2012 continued throughout 2013 which led us to report the best year in US Ecology's 62 year history. We set a new record in treatment and disposal revenue at $165.1 million, grew operating income by 30% to a record $52.9 million, reported record net income of $32.2 million and Adjusted EBITDA of $71.2 million, and saw adjusted earnings per share rise by over 31% to $1.82. Increased volume and a favorable service mix contributed to an improvement in our treatment and disposal margin, which rose by over 200 basis points to 47.8%. Delivering these record results on the heels of what had been the Company's strongest year in 2012 is a true testament to the value of our assets, broad permits and best-in-class employees across the entire organization.
In addition to delivering record financial results, in December 2013 we successfully raised over $96 million through an equity offering that allowed us to pay off our debt while leaving $74 million in cash on our balance sheet at December 31, 2013. This cash, combined with our debt capacity, provides the flexibility to further build out our disposal network by acquiring high quality treatment or disposal assets or service offerings in order to enhance our competitive position with a focus on strategic fit and long-term shareholder returns.
As we look ahead to 2014, our project pipeline is filling out nicely and demand for our services has continued to strengthen. While it will be a challenge to fully replace the project acceleration that benefited 2013, our exceptional sales team is determined to make it happen. Excluding the impact of foreign currency translation gains or losses and business development expenses, we expect 2014 adjusted EBITDA to range from $70 million to $74 million and, after incorporating a greater share count and higher anticipated tax rate, earnings to range from $1.50 to $1.60 per diluted share.
In closing, I would like to thank everyone that made 2013 such a great year. From everyone at our operating facilities, to our industry-leading sales and customer service teams, to our corporate office and support personnel, thank you for your continued support, strong commitment and execution and for helping to deliver results year in and year out. I am fortunate to be part of such an outstanding organization and look forward to working together to continue to grow our business and deliver sustainable long-term shareholder value in 2014 and beyond.
President and Chief Executive Officer