Wastewater considered for land application usually is from municipal or industrial wastewater treatment plants. Wastewater and sludge from municipal plants may be relatively innocuous if the raw sewage is domestic. The potential for increased concentrations of metals, organics, etc. increases as industrial input to the system increases. Industrial wastewater ranges from relatively clean by-products such as those from certain food processing and fermentation industries to those which are toxic or hazardous even in small amounts and require special attention.
7 Del. Admin. Code § 7103-16.0