The feasibility of storing wastewater samples from pulp and paper industry during more than 5 days (time recommend by ISO 5667-3:2018) for AOX determination was addresses in this study. Samples were collected before and after the aerobic biological treatment of a Portuguese industry. Experimental protocol included AOX measurements at days 4, 5, 6, 8, 11, 13, 15, 18 and 20 after sampling. Results obtained indicate that storage time is not matrix-dependent and it can be extended up to 20 days, which clearly improves management of laboratory activities concerning AOX determination.

Fertigation of agricultural crops using raw domestic sewage (RDS) has proven to be an excellent choice as opposed to conventional treatment. In this context, this work’spurpose was to evaluate the characteristics of the RDS to be applied in elephant grass fertirrigation as to its possible nutrients and pollutants. RDS was submitted to chemical (pH, COD, BOD5, Na, macronutrients and micronutrients) and physical (EC, TS, TFS and TVS) laboratory analyzes. Sodium was the referential chemical element for the definition of the RDS’s sheet to be applied to the ground, which was 215 mm of RDS at 26 cultivation weeks. NTK and P concentrations in RDS were 137 and 19.9 mg L-1, corresponding to the applied load of 296 and 43.9 kg ha-1 respectively, values that can be considered high. Furthermore, the mean concentrations of BOD5 and COD were 433 and 743 mg L-1 respectively, which leads to a COD/BOD5 ratio of 1,7, signaling a high biodegradability of organic matter in the RDS, indicative of good quality for agricultural purposes. Based on the applied sheet, it can be concluded that the RDS provided the availability of sufficient quantities of nutrients, ensuring good conditions for forage grass development.

Considering the significant expenses with fertilizer and irrigation, the use of wastewater in fertirrigation has been studied as an alternative, since it can supply part of the water demand and provide nutrients to the plants. The objective of this work was to evaluate the changes in soil nutrient/pollutant contents, with successive applications of Domestic Sewage. Two treatments were implanted, one of them without alternation and another with alternation in the direction of the flow. Chemical and physicochemical analyzes of soil in the superficial layer were made in samples collected after 10 and 26 weeks from the beginning of application. According to the results, there was an increase in the Total Nitrogen, Sodium content available and in the electrical conductivity values, but a decrease in Potassium, Organic Matter and pH values. Although Total Nitrogen levels increased, they remained below the limit of risk. Potassium reduction can be explained by the high mobility in the soil and the absorption of plants. However, the reduction in the content of organic matter and in the pH value is due to the effect of the nutrient supply, which favored the degradation of the native organic matter of the soil.