Plastics in Agriculture - the Problem and One Potential Solution

Abstract

For years, increased agricultural production and food quality has forced the increasing use of plastics in various activities. Currently, the plastic waste that results from the agricultural activity is recycled outside Portugal which increases the ecological footprint associated with the life cycle of these materials. It is crucial to consider new models for their valorisation at a local and regional level and in a circular economy perspective. In the scope of the Placarvões project (from plastic waste to activated carbons) it was elaborate the study of the types and quantities of plastics used in one of the biggest irrigated areas in Portugal, the Alqueva dam irrigation area. The methodology establishes a reference plot of 700 x 700 meters (49 ha) with is 90% irrigated land and details, for each crop, the types of plastic used throughout the culture cycle. Currently, the agricultural plastic volume in the Alqueva irrigation area is 1.880 tons per year, and with the expected growth of the irrigated area, it can reach 3.500 tons per year. Plastic are the plant protectors with the greatest influence, 56% in the total, followed by the plastic film. These 2 types of plastic represent about 85%. The crops that use most plastic are intensive olive groves, almond (plant protectors) and table grapes (plastic film) and represents more than 91% of the total plastic wastes of the area agricultural. Alentejo cannot afford not to value some waste, thus transforming it into valuable materials that allow increasing regional yields. The Placarvões solution involves the production of activated carbons from plastic wastes derived from agriculture, disposable plastics and the fraction rest that results from the mechanical/biological treatment of municipal solid wastes (CDR). The activated carbons were produced by physical and chemical activation. The activated carbons were tested as adsorbents for the removal of 2,4-D and MCPA from a liquid phase. This solution may be applicable in the water waste treatment in the region, contributing to the circular economy in the territory.