Effects of LED lights and cytokinin on the phytotreatment of simulated swine wastewater by Azolla spp.: Pollutant removal and biomass valorization.

Phytoremediation is an eco-friendly and affordable option for tackling wastewater pollutants. The study focused on how light-emitting diodes (LED) light exposure, measured by intensity and duration (photoperiod), along with cytokinin, impacts Azolla microphylla's simulated swine wastewater treatment performance and biomass production. Under optimal treatment conditions, high removals of COD (89.2 % to 90.8 %), N-NH4+ (72.6 % to 91.2 %), N-NO3- (84.4 % to 88.6 %), Cu (75.4 % to 86.4 %), sulfamethoxazole (77.0 % to 79.0 %), P-PO43- (54.1 % to 59.9 %) and DOC (67.4 % to 71.3 %) while Zn presented a more moderate reduction (2.0 % to 9.7 %). Biomass productivity reached up to 34.8 t ha-1 yr-1. Protein production accounted for 23 % to 27 % of dry weight, while lipids ranged from 20 % to 34 % of dry biomass. Carbohydrate content varied from 8 % to 28 % of fresh weight. Higher light intensities, with both high or low values of photoperiods, and low concentrations of cytokinin were identified as optimal conditions for removal of almost all pollutants. However, pollutant removal was impacted differently by LED light and cytokinin concentration. In treatment conditions with the shortest photoperiods (8 h), the lowest residual Cu and Zn concentrations, whereas with longer photoperiods (24 h), the lowest residual concentrations of N-NH4+ and P-PO43- concentrations were recorded. On the other hand, SMX was the only parameter in which cytokinin had a clear influence on its removal, with the lowest residual concentration observed under 8-hour photoperiods combined with the lowest tested cytokinin concentrations (0.3 mg L-1). For residual COD and N-NO3-, no discernible pattern was evident for any of the analyzed factors. Therefore, the study demonstrates the potential for treating simulated swine wastewater using Azolla microphylla, aligned with its ability to produce biomass rich in high-value compounds.

Desorption of Coffee Pulp Used as an Adsorbent Material for Cr(III and VI) Ions in Synthetic Wastewater: A Preliminary Study.

Some of the diverse agro-industrial waste generated in primary or secondary stages have proved to be promising biomaterials for treating aqueous effluents contaminated, in this case, with heavy metals. Therefore, it is necessary to know their optimal operating conditions and the regeneration or reusability of the solid by-product, an aspect related to desorption. Considering the above, this article presents the findings of a preliminary study related to the desorption process of coffee pulp without physicochemical modification (Castilla variety), an agricultural waste used as a sorbent of Cr(III and VI) ions in synthetic wastewater. The desorption efficiency of four eluting agents at defined concentrations (0.10M)-HC1, HNO3, H2SO4, and EDTA-was evaluated in a time interval of 1 to 9 days. Likewise, the proposals for the sorption and/or desorption mechanisms proposed and reported in the literature with respect to the use of biosorbents derived from the coffee crop are presented. With respect to the results, the coffee pulp used in previous studies of the adsorption of chromium species mentioned (optimal conditions in synthetic water of particle size 180 µm, dose 20 g·L-1, agitation 100 RPM, room temperature, time of 90 to 105 min) showed efficiencies in the removal of Cr(III) and Cr(VI) of 93.26% and 74.80%, respectively. Regarding the extracting substances used, H2SO4 0.10 M was the one that presented the highest desorption percentage in both chromic species, with a desorption of 45.75% Cr(VI) and 66.84% Cr(III) in periods of 5 and 9 days, respectively, with agitation of 100 RPM and room temperature. Finally, the dissemination of preliminary results on the desorption of coffee pulp contaminated with chromic species without physicochemical modification is novel in this study, as similar work with this specific material has not yet been reported in the literature. On the other hand, the limitations of the study and future research are related to the evaluation at different concentrations and of other extractor solutions that allow improving the efficiency of desorption of these chemical species in a shorter time from the coffee pulp (with and without modification) as well as the reuse cycles. As a result, the desorption of coffee pulp used as an adsorbent material in real water could help researchers identify the possible interfering factors that affect the process (foreign anions and cations, organic matter, environmental conditions, among others).

Tratamento anaeróbio de pentaclorofenol em reator de leito fluidificado alimentado com água residuária sintética contendo glicose como fonte única de carbono / Anaerobic treatment of pentachlorophenol in a fluidized bed reactor fed with synthetic wastewater containing glucose as a single carbon source

Neste trabalho foi utilizado um reator anaeróbio de leito fluidificado (RALF), tratando água residuária sintética contendo pentaclorofenol (PCP), submetido a condições operacionais menos idealizadas. Utilizou-se um reator com volume de 16 litros, com partículas de carvão ativado granular como meio suporte. O desempenho do reator foi verificado pelas análises usuais de monitoramento (pH, alcalinidade, DQO, ácidos voláteis) e também por análises de microscopia e concentração de PCP. A presença de PCP no sistema, nas concentrações utilizadas, não alterou de maneira significativa a qualidade da biomassa presente, e nem os parâmetros de monitoramento. Em concentrações afluentes de PCP variando de 1 a 6 mg/L, foram observadas eficiências médias de remoção de 92 por cento e 70 por cento, respectivamente.

In the present work, an anaerobic fluidized bed reactor (AFBR) was used for the treatment of a synthetic wastewater containing pentachlorophenol (PCP) subjected to less idealized operating conditions. The reactor was a 16 litres tank with granular activated carbon particles as support media. Evaluation of AFBR performance was done by the analysis of usual monitoring parameters (pH, alkalinity, COD, volatile acids) together with microscopy and PCP concentration analysis. The presence of PCP under the concentrations used did not significantly alter the amount of biomass and the performance monitoring parameters. Removal average efficiencies of the order of 92 percent and 70 percent were obtained for PCP inflow concentrations in the range of 1 to 6mg/l.