The regulatory effluent oil limit which is the allowable quantity of hydrocarbons in industrial and stormwater effluents varies from one country to another. Several authors have suggested the need to improve the design methods of conventional oil-water separators because current design methods do not address the quality of effluents produced despite the fact that the conventional oil-water separator is the predominant wastewater treatment facility in developing countries. Regulatory effluent oil limit and oil separation efficiency are not design parameters of the current standard design methods for conventional oil-water separators but there is pressure from environmental regulatory agencies on companies over compliance with regulatory effluent oil limit for industrial wastewaters. This research work conducted a survey on the oil content of the wastewater effluents of some functional conventional oil-water separators in the Niger Delta, Nigeria. Sequel to the outcome of the survey, this work invented novel design methods for conventional oil-water separators titled: novel design approach, innovative design approach and alternative design approach through mathematical modeling. The novel design methods apply the concept of design volume, novel sizing data and novel mathematical models to design conventional oil-water separators that conform to American Petroleum Institute (API) design criteria for conventional oil-water separators; taking into account oil separation efficiency and the regulatory effluent oil limit of a country to establish the technical basis for the periodic evaluation of separator performance and evaluation of compliance with the environmental regulation. The conventional oil-water separators designed with the novel design methods conformed to API design criteria and their dimensions are similar to dimensions of separators designed with the City of Tacoma design approach (a certified design approach), thus validating the novel design methods for the design of conventional oil-water separators. The novel design methods have global applicability. They can be applied in every country.
Keywords: Chemical engineering; Civil engineering; Environmental science.