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Study of the effect of two wwt's discharges on the benthic macroinvertebrate communities' structure of the River Tinto (Portugal)The Water Framework Directive (DQA-2000/60/ EC) establishes, as one of its main objectives, the achievement of good ecological status of water bodies and introduces the concept of "ecological status", which includes the study of a broad set of parameters and factors to determining the health of an ecosystem. This work is part of a project whose main objective is the rehabilitation of a small urban river in the north of Portugal, the Tinto river, that presents a high degree of environmental degradation. This work aims to study the effect of the two wastewater treatment plants (WWTP's) discharges in the structure of the benthic macroinvertebrate communities. The study compares results (metrics and indices) obtained from the analysis of benthic macroinvertebrates samples collected in river sections upstream and downstream of the discharges of WWTP's, between october 2015 and july 2017, and values of hydro-morphological and physico-chemical parameters. Although the benthic macroinvertebrate communities are very conditioned by the bad status of the Tinto river, in the sections downstream of the WWTP's the macroinvrtebrates communities present characteristics that indicate a higher degree of environmental disturbance.

The objective of this work was to study the growth of microalgae Chlorella fusca ACOI 621, Chlorella vulgaris ACOI 879, Scenedesmus acutus ACOI 538 and Scenedesmus obliquus ACOI 550, in the presence and absence of Cr(VI). The microalgae growth was assessed as a function of different parameters, particularly, temperature, pH and Cr(VI) addition. Although growth inhibition due to Cr(VI) toxicity is rather visible for Cr(VI) ≥ 5 mg L-1 , concentrations up to 1 mg L-1 seem not to seriously affect the algal growth. The production of metabolites (expressed in terms of dissolved organic carbon released from the microalgae to the solution) EXPRESSES the inhibition caused by toxic levels of Cr(VI) in the four microalgae, which adversely affects the sedimentation. The more marked effect of Cr(VI) on algal growth is observed in C. vulgaris culture and all these microalgae can be used for the removal of heavy metals from wastewaters. All in all, C. fusca appears to be the best choice for work involving heavy metal removal.