Performance of an integrated system combining microalgae and vertical flow constructed wetlands for urban wastewater treatment

Abstract

The present study investigated the performance of an integrated system, combining the sequential use of microalgae (MA) and vertical flow constructed wetland (VFCW) for the treatment of wastewaters produced at a university campus. Ecotoxicity and phytotoxicity assays were performed using respectively Daphnia magna and Lactuca sativa, whereas the genotoxicity of the wastewaters was assessed by using D. magna and Allium cepa. The results revealed that the major environmental impacts of the studied wastewaters are associated with the high eutrophication potential, due to high N-NH (68.8 ± 25.7 mg L), total P (7.71 ± 2.5 mg L), and BOD (526.4 ± 177 mg L) values, pathogenic load, and genototoxicity (p < 0.0001). The results also showed that the integrated system (MA + VFCW) was not able to satisfactory reduce the total p values (only 4%). Nevertheless, the MA + VFCW system achieved very promising results for the nitrogen removal, with emphasis on N-NH removal (100%) and the highest BOD removal (57%). Neither the raw wastewaters nor the treated wastewaters were phytotoxic. The integrated system completely eliminated the ecotoxicity (100%) and genotoxicity (n.s.) of the raw wastewater and showed decontamination potential. Thus, the integrated system emerges as an innovative environmental technology and, with minor adjustments, might be efficiently used in large scale and eventually replace conventional wastewater treatment systems.

Perspectives on Microalgal Biofilm Systems with Respect to Integration into Wastewater Treatment Technologies and Phosphorus Scarcity

“…Our previous work demonstrated P removal efficiency averaging 98% [27]. Silveira et al (2017) [48] presented an integrated system of microalgal cultivation in a suspension culture connected to vertical flow constructed wetlands for treatment of raw municipal wastewater. However, their system was rather inefficient with respect to P removal.…”

Energy recovery by anaerobic digestion of algal biomass from integrated microalgae/constructed wetland wastewater treatment

“…The WWTP was configured to meet the demands of wastewater produced by a population equivalent to 18,000 people, operating with an average flow of approximately 103 m 3 day −1 . Fluctuations range from 129.6 to 57.6 m 3 day −1 and flow peaks occur between 12 and 17 h (Silveira et al 2017 ). For this experiment, six stages of analyses were carried out at the Research Center in Energy and Sustainable Technologies (RCEST) of the University of Vale do Taquari—UNIVATES, located at the campus of Lajeado/RS, Brazil.…”

Nutrient removal efficiency using microalgae in different photoperiod cycles, combined with constructed wetland in a wastewater treatment plant

“…Água vol. 16 n. 5, e2692 -Taubaté 2021 of soluble P after MT may be related to the life cycle of microalgae, since during the decay phase, that is, cell death, the cellular content may add soluble P to the wastewater, thus increasing the load for the Sand Biofilter System + CW (Silveira et al, 2017).…”