Enhancement of total nitrogen removal through effluent recirculation and fate of PPCPs in a hybrid constructed wetland system treating urban wastewater

The effect of effluent recirculation on the removal of total nitrogen (TN) and eight pharmaceuticals and personal care products (PPCPs) was evaluated during 9 months in an experimental hybrid constructed wetland (CW) system applied in the treatment of urban wastewater. An Imhoff tank was followed by three stages of CWs (two 1.5-m2 vertical subsurface flow (VF) beds alternating feed-rest cycles, a 2-m2 horizontal (HF) and a 2-m2 free water surface (FWS) wetland in series). A fraction of the final effluent was recycled back to the Imhoff tank with a recirculation rate of 50% (hydraulic loading rate = 0.37 m d− 1). The system's performance varied throughout the study. In Period I (summer) consistently high load removal efficiencies of TN (89 ± 5%) and a removal rate of 6.6 ± 1.4 g TN m− 2 d− 1 were exhibited. In Period II (fall), the poor performance of the FWS during the senescence of macrophytes caused a large increase in organic matter, solids and nutrient concentrations, drastically deteriorating water quality. The determination of PPCPs was conducted during this period. Recalcitrant compounds, namely sulfamethoxazole, carbamazapine, TCEP and sucralose were negligibly removed in all CWs. However, noteworthy was the ≈ 30% removal of sucralose in the VF wetland. Caffeine (80%) and fluoxetine (27%) showed similar elimination rates in both VF and HF units, whereas trimethoprim and DEET were significantly better removed in the VF than in the HF. The concentration of the four latter compounds showed a severe increase in the FWS, indicating possible desorption from the sediment/biomass during adverse conditions. Harvesting of the aboveground biomass in this unit returned the system's performance back to normality (Period III), achieving 77 ± 7% TN removal despite the winter season, proving effluent recirculation as an effective strategy for TN removal in hybrid CW systems when stringent restrictions are in place

Removal of organic carbon, nitrogen, emerging contaminants and fluorescing organic matter in different constructed wetland configurations

The elimination of organic carbon, nitrogen, five emerging organic contaminants (EOCs) and fluorescence signature was evaluated in two treatment lines comprising different constructed wetland (CW) configurations: (i) partially saturated vertical subsurface flow (SVF) wetland (treatment line 1) and (ii) unsaturated vertical subsurface flow (UVF), horizontal subsurface flow (HF) and free water surface (FWS) wetlands in series (treatment line 2). Results showed important differences between the different CW configurations. The highest removal of BOD5 (81%), COD (67%), TOC (72%) and fluorescing organic matter were observed in the UVF wetland, whereas the HF and FWS wetlands were the most efficient units for total nitrogen removal (60 and 69%, respectively). The SVF wetland showed a greater performance in the reduction of total nitrogen than the UVF bed (52 vs. 35%). In addition, the SVF wetland exhibited a higher removal of the EOCs caffeine (95 vs. 90%), trimethoprim (99 vs. 87%) and sulfamethoxazole (64 vs. 4%), as opposed to DEET (34 vs. 63%), whose removal was superior in the UVF unit. Sucralose was negligibly removed in all the CWs. PARAFAC analysis of fluorescence measurements revealed that the proteinaceous tryptophan-like fluorescent component was the most highly removed one in all the investigated CWs (>28%) and, particularly, in the UVF wetland (66%), whereas humic and fulvic-like components resulted recalcitrant to decomposition. Increases of fluorescence intensities were often observed for fulvic-like substances in CWs operating with saturation of the bed, and these were particularly relevant in the SVF unit. Finally, important correlations (r > 0.7) between the tryptophan-like fluorescent component and the wastewater quality parameters COD and BOD5 suggest fluorescence spectroscopy as an useful monitoring tool for water treatment efficiency in CW systems

Uso de leitos cultivados de fluxo vertical por batelada no pós-tratamento de efluente de reator anaeróbio compartimentado Post-treatment of effluent of anaerobic baffled reactor using batchwise vertical flow constructed wetland beds

Neste trabalho avaliou-se o desempenho de um Reator Anaeróbio Compartimentado (RAC) de duas câmaras em série, seguido de três leitos cultivados (constructed wetlands) de fluxo vertical por batelada. A unidade experimental, em escala piloto, foi instalada na Faculdade de Engenharia Agrícola - UNICAMP, Campinas, SP, Brasil. O volume total do reator era de 2,3 m³ (TDH de 12 h). O efluente do RAC foi tratado em três leitos, dois cultivados com macrófitas (gêneros Typha sp. e Eleocharis sp.) e um utilizado como controle (não cultivado). Os leitos, com 2,0 m³ cada um e brita #2 (24 - 35 mm) como meio suporte, operaram com fluxo vertical por batelada (com tempos de reação de 24, 48, 72 e 96 h). Na avaliação do RAC, observou-se tendência de estabilização dos parâmetros pH, alcalinidade, ácidos voláteis, sólidos sedimentáveis e suspensos totais, porém a remoção de DQO revelou-se limitada (50%). Nos leitos cultivados o aumento do tempo de reação (até 72 h) foi acompanhado pelo aumento de remoção de turbidez, DQO, fósforo e nitrato. O melhor desempenho de remoção de fósforo total foi obtido no leito vegetado com Typha sp para os tempos de 72 e 96 h, respectivamente, de 30 e 25%.<br>This study evaluated the performance of vertical constructed wetlands treating effluent of anaerobic baffled reactor. The anaerobic reactor volume was 2.3 m³; it was operated with daily flow of 4.6 m³ (12 hours Hydraulic Retention Time). The reactor effluent was split into three wetlands beds, two of them cultivated with macrophytes (Typha sp. and Eleocharis sp.), and one control. The wetlands were operated as a batch reactor. The medium utilized was gravel, the size ranging from 7 to 12 mm. The reaction time for each cycle (filling - reaction - drainage) was 24, 48, 72, and 96 h. The anaerobic reactor achieved the following removal rates: settable solids, 93%; suspended solids, 80%; and COD 39%. The increase in reaction time (up to 72 h) for the constructed wetlands was followed by an increase in turbidity, COD, phosphorus and nitrate removal rates. The Typha sp. bed presented the best phosphorus removal rates. For 72 and 96 h reaction time the observed removal rate was 30 and 25%, respectively

Clinical and epidemiological features of definitive and presumed loxoscelism in São Paulo, Brazil Aspectos clínicos e epidemiológicos do loxoscelismo em São Paulo, Brasil

A retrospective study analysed 359 proven or presume cases of loxoscelism seen at the Hospital Vital Brazil, Instituto Butantan, São Paulo, Brazil, between 1985 and 1996. The spider was identified in 14%. The bites occurred predominantly in the urban areas (73%) between September and February. Patients > 14 years were commonest inflicted (92%) and 41% were bitten while getting dressed. Only 11% sought medical care within the first 12 hours post bite. Cutaneous loxoscelism was the commonest form presenting (96%); commonest manifestations were: pain (76%), erythema (72%), edema with enduration (66%), ecchymosis (39%). Skin necrosis occurred in 53% of patients, most frequently seen on trunk, tigh and upper arm, and when patients seek medical care more than 72 hours after bite. Local infection was detected in 12 patients (3%). Hemolysis was confirmed in 4 cases (1.1%). Generalised cutaneous rash, fever and headache were also observed in 48% of the total of patients. None of them had acute renal failure or died. Treatment usually involved antivenom administration (66%), being associated with corticosteroids (47%) or dapsone (30%). Presumptive diagnosis of loxoscelism may be established based on clinical and epidemiological findings. Further investigations are required to prove the value of antivenom and other treatment schedules.<br>Foram analisados, em um estudo retrospectivo, 359 casos de loxoscelismo comprovados ou presumidos, acompanhados no Hospital Vital Brazil, Instituto Butantan, São Paulo, Brasil, entre 1985 e 1996. A aranha foi identificada em 14% dos casos. Os acidentes predominaram nas áreas urbanas (73%), entre setembro e fevereiro. Pacientes maiores de 14 anos foram mais freqüentemente atingidos (92%) e 41% foram picados ao se vestir. Apenas 11% procuraram o serviço médico nas primeiras horas após a picada. A forma cutânea foi a mais freqüente (96%), sendo as principais manifestações descritas: dor (76%), eritema (72%), edema com enduração (66%), equimose (39%). Necrose cutânea ocorreu em 53% dos pacientes, sendo mais freqüentemente observada no tronco, coxa e braço, e naqueles que procuraram atendimento médico mais de 72 horas após o acidente. Infecção local foi detectada em 12 pacientes (3%). A hemólise foi confirmada em 4 casos (1,1%). Exantema generalizado, febre e cefaléia foram observados em 48% dos pacientes. Não se verificou insuficiência renal ou óbito. O antiveneno foi administrado em 66% dos casos, associado a corticosteróide em 47% ou a dapsona em 30%. O diagnóstico presuntivo de loxoscelismo pode ser estabelecido baseado em achados clínicos e epidemiológicos. Maiores investigações são necessárias para se comprovar o valor do antiveneno e outras drogas