Before I answer your question, keep in mind that as a single member LLC you can be classified as either a disregarded entity (i.e. sole proprietor) or corporation for tax purposes but legally maintain LLC status.
As a disregarded entity you are treated as a sole proprietorship for tax purposes and would simply report income and expenses on Schedule C of your 1040 personal tax return. To be treated as a corporation you need to file Form 8832 and elect to be classified as a corporation. You would be required to file tax form 1120 as a corporation.
The short answer to your question is that a return of capital is not a taxable event. More specifically, the Internal Revenue Code states that a non-dividend distribution in the form of a return of capital to a single member LLC is tax-free to the extent that it does not exceed the stockholder's stock basis.
If the business had income or experienced another taxable event (i.e. sale) during the year then you would likely be subject to income taxes. Based on the information you have provided, it appears as though you will have income for the year and thus will be subject to income tax. However, the return of the initial capital investment is not taxable.
Keep up the good work and let us know if you have any additional tax questions.