Mapping microplastics in Cadiz (Spain): Occurrence of microplastics in municipal and industrial wastewaters

Abstract

The high concentrations of microplastics (MPs) detected in the environment point to the need to carry out studies of their occurrence and distribution worldwide. Addressing this challenge, the present study has been carried out for the province of Cadiz, Spain. To this end, the influents and effluents of 5 municipal wastewater treatment plants (representing 50 % of the total wastewater in Cadiz) and 2 industrial plants treating wastewater from an industrial estate and a large marine construction firm that builds ships and offshore platforms (5 MWWTPs and 2 IWWTPs) have been studied for the first time. MP levels were higher in IWWTPs than in MWWTPs, especially in the wastewaters from the marine construction company. Removal efficiencies ranged between 78 and 97 %. The size and shape distribution of MPs in the effluents resembled that in the influents, suggesting that no preferential removal of MPs occurred in the MWWTPs or IWWTPs with respect to shape and size. PVC, HDPE, PEMA, PP, PS and PE were the most common MPs detected in the influents of the studied WWTPs. The relative contribution of MPs (MPs/L) to the environment from the IWWTPs compared to that from the MWWTPs was found to be highly significant. Results suggested that around 8.5*1011 of MPs/year could be discharged into the environment by the treated wastewaters under study. The results of this paper comprise useful tools to obtain in-depth knowledge of MPs in different kinds of wastewater treatment plants and map an important environmental location (close to the Straits of Gibraltar linking the Atlantic Ocean and the Mediterranean Sea).