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The present research investigated the efficiency of an integrated system for the treatment of wastewaters generated at a rural property located in the city of Vera Cruz do Sul, southern Brazil. The integrated system was composed of an anaerobic unit (UASB/AB), 4 subsurface constructed wetlands (SSFCWs), and two photoreactors (UV-254 nm). The evaluation of the performance was based on the reduction of the load parameters and mainly on the detoxification of the wastewaters. The ecotoxicological analysis included short-term assays with the microcrustacean Daphnia magna whereas the cytogenetic potential of the wastewaters was assessed by using the Allium cepa test system. On the one hand, the raw wastewaters presented a strong pollution potential due to high COD, BOD5, TKN, N-NH3 and total P values. On the other hand, the effluents treated by the integrated system showed high reductions of the abovementioned parameters and fully attend the Brazilian and International legal requirements. Furthermore, the treated wastewaters presented a complete absence of the acute ecotoxicity (100%) as well as significant reductions of the cytotoxicity, genotoxicity, and mutagenicity when compared to the raw wastewaters. Therefore, the investigated system can be considered an interesting low-cost sanitation alternative, especially for wastewaters produced in rural areas, where decentralized systems are more suitable. Besides, the results obtained in the present work demonstrate the importance of including toxicity analysis in the monitoring of waters and wastewaters in order to obtain a broader evaluation concerning the efficiency of different treatment systems.

The universalization and decentralization of wastewater treatment is one of the greatest challenges faced in Brazil. In this context, Constructed Wetlands (CWs) may be considered environment friendly and economically viable alternative for geographically remote locations, having fewer financial resources and infrastructure. During the last years, studies have investigated different configurations aiming to increase the capacity of CW to remove nutrients, mainly phosphorus (P) and reinforced its importance in ecological and landscape contexts. Thus, the present study evaluated the performance of a hybrid system combining Floating, Vertical and Horizontal Flow CWs to treat urban wastewaters. A removable adsorbent barrier was developed to improve the removal of P and a polyculture with ornamental plants was used to add landscape potential. The obtained results showed a promising nutrients removal capacity of the hybrid system, with mean removal rates of 94.0% for total P, 93.8% for ammonium nitrogen (N−NH3), 93.8% for total nitrogen (N), 80.0% for dissolved organic carbon (DOC), 84.0% for biochemical oxygen demand (BDO5), 77.0% for chemical oxygen demand (COD) and 99.7% for turbidity. The integrated system kept its ability to remove pollutants during the 11 months of operation (January to December 2019), without substrate saturation, and also maintaining P values within the limits allowed by current Brazilian (CONSEMA Resolution 355/17 (3 mg L−1)) and international legislation (UWTD 91/271/EEC (2 mg L−1)). The landscape benefits were extremely positive mainly due to the flowering of Canna generalis and its greater biomass production. By crossing the biomass data and the accumulation of nutrients in the tissues of the aerial part it was possible to verify that the contribution of the plants in the N removal from the system reached 8.08% while the P decrease attained 17.92% in the horizontal sub-surface flow constructed wetland (HSSFCWs). Therefore, the developed system enabled an efficient removal of nutrients throughout the monitoring period, enhancing the wastewater quality and potentializing its reuse for different purposes.

This study investigates the combination of constructed wetlands (CW) with photocatalytic ozonation (UV/TiO 2 /O 3 ) for the treatment of university sewage. Both of the tested CWs configurations were vegetated with Hymenachne grumosa in three stages of subsurface flow sequence. The CWs were designed with the following characteristics: vegetated system built within a plastic greenhouse (CW-1) and vegetated system built outdoors (CW-2). The CWs were operated in continuous flow with hydraulic retention time (HRT) of 1.87 days (Phase I) and intermittently for a 7-day period (Phase II). The UV/TiO 2 /O 3 reactor was applied after CW-1 (Phase III) to improve the quality of treated wastewater for reuse. The results revealed that the CW-1 + UV/TiO 2 /O 3 reactor batch configuration reduced COD and BOD 5 by an average of 62.1% and 88.7%, respectively. TKN, NH 3 –N and total P reductions averaged 27.6%, 27.1% and 63.4%, respectively. One of the disadvantages of the UV/TiO 2 /O 3 reactor was the saturation of the ramp after 4 h of operation. In terms of acute detoxification, the influent decreased from moderately toxic to slightly toxic in the phytoremediation process (Phase I). Chronic detoxification was ineffective at this phase and effluents remained highly toxic. In the UV/TiO 2 /O 3 reactor (Phases II and III), detoxification was inefficient, increasing the acute toxicity of the effluent and maintaining it extremely toxic on chronic toxicity tests. Disinfection efficacy is particularly attributed to UV/TiO 2 /O 3 , greatly reducing the microbial load (CFU/100 mL) from 10 5 to below the determination limit.