Loans receivable (Details) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable	$ 3,769,016	$ 5,610,867
Less current portion	1,633,588	1,841,851
Loans receivable, excluding current portion	2,135,428	3,769,016
Two loans originally aggregating $10,996,290, bearing interest at 6.5% per annum, receivable in aggregate monthly installments of $124,827 to June 2019, and secured by the machinery and equipment of the North Side Water Works plant [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable	3,448,051	4,678,355
Two loans originally aggregating $3,671,039, bearing interest at 6.5% per annum, receivable in aggregate monthly installments of $54,513 to June 2017, and secured by the machinery and equipment of the Red Gate plant [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans receivable	$ 320,965	$ 932,512