RESUMO
Hydrothermal carbonization transforms biomass into value-added material called hydrochar. The release of nutrients (P, N, Ca, Mg, and K) and organic carbon (TOC) from hydrochar in different extractive solutions was investigated in this study. Two sets of hydrochar were produced: (i) hydrochar prepared from sugarcane bagasse and vinasse mixture (BV-HC) and (ii) hydrochar prepared by the addition of H3PO4 to this mixture (BVA-HC). Both hydrochar types released significative amounts of nutrient and organic carbon, mainly Ca (5.0 mg g-1) in the mixture (KCl, K2SO4, NaOH, 1:1:1) extractive solution and TOC (72.6 mg g-1) in the NaOH extractive solution, for BV-HC. Nutrient release was influenced by pH and ionic strength. The release of P, Ca, and Mg was affected by the presence of insoluble phosphate phases in BVA-HC. The release of nutrients P, N, Ca, Mg, and K and organic carbon demonstrated that hydrochar has potential for soil application purposes.
Assuntos
Carbono/análise , Resíduos Industriais/análise , Nutrientes/análise , Extratos Vegetais/análise , Saccharum/química , Resíduos/análise , Cálcio/análise , Cálcio/isolamento & purificação , Carbono/isolamento & purificação , Celulose/química , Nutrientes/isolamento & purificação , Extratos Vegetais/isolamento & purificação , Solo/químicaRESUMO
Due to the complex nature of the wastewater (both domestic and non-domestic) composition, biological processes are widely used to remove nutrients, such as carbon (C), nitrogen (N), and phosphorous (P), which cause instability and hence contribute to the damage of water bodies. Systems with different configurations have been developed (including anaerobic, anoxic, and aerobic conditions) for the joint removal of carbon, nitrogen, and phosphorus. The goal of this research is to evaluate the extracellular activity of ß-glucosidase and phosphatase enzymes in a University of Cape Town (UCT) system fed with two synthetic wastewaters of different molecular complexity. Both types of waters have medium strength characteristics similar to those of domestic wastewater with a mean C/N/P ratio of 100:13:1. The operation parameters were hydraulic retention time (HRT) of 10 h, solid retention time (SRT) of 12 days, mean concentration of the influent in terms of chemical oxygen demand (COD), total Kjeldahl nitrogen (TKN), and total phosphorus (TP) of 600, 80, and 6 mg/L, respectively. According to the results obtained, statistically significant differences have been found in the extracellular enzyme activities with the evaluated wastewaters and in the units comprising the treatment system in some of the cases. An analysis of principal components showed that the extracellular enzymatic activity has been correlated to nutrient concentration in wastewater, biomass concentration in the system, and metabolic conditions of treatment phases. Additionally, this research has allowed determining an inverse relationship between wastewater biodegradability and the extracellular enzyme activity of ß-glucosidase and phosphatase. These results highlight the importance of including the analysis of biomass biochemical characteristics as control methods in wastewater treatment systems for the nutrient removal.
Assuntos
Hidrolases/metabolismo , Eliminação de Resíduos Líquidos , Águas Residuárias/análise , Purificação da Água , Análise da Demanda Biológica de Oxigênio , Biomassa , Reatores Biológicos , Carbono/isolamento & purificação , Concentração de Íons de Hidrogênio , Nitrogênio/isolamento & purificação , Monoéster Fosfórico Hidrolases/metabolismo , Fósforo/isolamento & purificação , África do Sul , beta-Glucosidase/metabolismoRESUMO
New carbonaceous materials were obtained using a fast aqueous solution combustion process from mixtures of exhausted coffee, ammonium nitrate (oxidizer) and urea (fuel) heated at 600, 700, 800 or 900 °C. The resulting powders were effective adsorbents for removing Co(II) and Cd(II) from aqueous solutions. Exhausted coffee was also calcined at different temperatures and compared. The products were characterized, and the obtained carbons had BET specific surface areas of 114.27-390.85 m(2)/g and pore diameters of 4.19 to 2.44 nm when the temperature was increased from 600 to 800 °C. Cobalt and cadmium adsorption by the carbonaceous materials was correlated with the maximum adsorption capacities and specific surface areas of the materials. The method reported here is advantageous because it only required 5 min of reaction to improve the textural properties of carbon obtained from exhausted coffee, which play an important role in the material's cobalt and cadmium adsorption capacities.
Assuntos
Cádmio/química , Carbono/isolamento & purificação , Cobalto/química , Café/química , Eliminação de Resíduos/métodos , Poluentes Químicos da Água/química , Purificação da Água/métodos , Adsorção , Oxirredução , TemperaturaRESUMO
The removal of nitrogen and organic matter using a single reactor has been a common focus of investigation, and reactors operated in batch mode and under intermittent aeration have attracted special attention. This study aimed to evaluate the application of a new reactor configuration consisting of a fixed-bed reactor that was operated under conditions of continuous feeding and intermittent aeration. The reactor was built using acrylic, with a working volume of 6.1L. The fixed bed used for biomass support was composed of polyurethane foam cylinders vertically oriented inside the reaction zone. The reactor was operated under intermittent aeration (2h aerated and 1h non-aerated) and a recirculation ratio Q(r)/Q=5. Three different operating conditions (Phase I, Phase II, and Phase III) corresponding to hydraulic retention times (HRT) of 12h, 8h, and 10h, respectively, were tested. In Phase I, the system achieved total nitrogen (TN) and chemical oxygen demand (COD) removal efficiencies of 82% and 89%, respectively. At HRTs of 8 h and 10 h, the reactor was unstable with respect to TN removal, and the average resultant removal efficiencies were 49% and 45%, respectively. However, COD removal efficiencies remained high with mean values of 85% and 88% for Phases II and III, respectively. Based on these results, it can be concluded that this new reactor configuration constitutes an alternative method for effective removal of organic matter and nitrogen from wastewater.
Assuntos
Carbono/isolamento & purificação , Nitrogênio/isolamento & purificação , Purificação da Água/métodos , Aerobiose , Reatores BiológicosRESUMO
The evaluation of simultaneous removal of carbon and nitrogen in an anaerobic inverse fluidized bed reactor is described. Continuous and batch experiments were used, with synthetic wastewater and glucose as the carbon source with two different nitrate concentrations of 100 and 250 mg N-NO3/L. The evolution of substrates and the concentrations of intermediary products in the gas phase were followed. Results indicate that the use of the biofilm in the inverse fluidized bed reactor allows the expression of denitrification and methanization activities simultaneously without physical or time separation. The removal of nitrogen with both the feeding of 100 and 250 mgN-NO3/L was higher than 90%, while the removal of carbon was 65% on average for the feeding with 100 mgN-NO3/L and 70% on average for the feeding with 250 mg N-NO3/L. This carbon degradation is equivalent to that obtained during the operation of the reactor in the period previous to the nitrate feeding. It was found that by using high values of the COD/N ratio, the dissimilative reduction of nitrates is favoured. Denitrification and anaerobic digestion occurs simultaneously under low values of COD/N.
Assuntos
Carbono/isolamento & purificação , Nitrogênio/isolamento & purificação , Anaerobiose , Recuperação e Remediação AmbientalRESUMO
The aim of the present work was to assess the response of microbial functional diversity to organic soil amendment and the relationship between the microbial functional diversity and soil carbon availability. Household solid waste compost, horse and rabbit manure and chicken manure were applied at two doses. The same undisturbed soil type (Vertic Argiudoll) was used as reference. Soil suspensions were applied to Biolog EcoPlate and average color development (AWCD), richness (R) and Shannon-Weaver index (H) were calculated. The amendment incorporation resulted in significant increases (p < 0.05) in AWCD, R and H compared to the unamended plots. The regression functions showed linear relationships when R and H were related to soil organic carbon (R(2) = 0.77 and 0.72, respectively). Principal component analysis allowed the differentiation of treatments from the control and the undisturbed sites. The Biolog EcoPlate assay was sensitive to changes in the short term due to management practices.
Assuntos
Agricultura/métodos , Bactérias/classificação , Bactérias/isolamento & purificação , Carbono/isolamento & purificação , Fertilizantes/microbiologia , Esterco/microbiologia , Microbiologia do Solo , Bactérias/genética , Fertilizantes/análise , Variação Genética , Esterco/análise , Solo/análiseRESUMO
Refinery wastewaters may contain aromatic compounds and high concentrations of sulfide and ammonium which must be removed before discharging into water bodies. In this work, biological denitrification was used to eliminate carbon, nitrogen and sulfur in an anaerobic continuous stirred tank reactor of 1.3 L and a hydraulic retention time of 2 d. Acetate and nitrate at a C/N ratio of 1.45 were fed at loading rates of 0.29 kg C/m3 d and 0.2 kg N/m3 d, respectively. Under steady-state denitrifying conditions, the carbon and nitrogen removal efficiencies were higher than 90%. Also, under these conditions, sulfide (S(2-)) was fed to the reactor at several sulfide loading rates (0.042-0.294 kg S(2-)/m3 d). The high nitrate removal efficiency of the denitrification process was maintained along the whole process, whereas the carbon removal was 65% even at sulfide loading rates of 0.294 kg S(2-)/m3 d. The sulfide removal increased up to approximately 99% via partial oxidation to insoluble elemental sulfur (S0) that accumulated inside the reactor. These results indicated that denitrification is a feasible process for the simultaneous removal of nitrogen, carbon and sulfur from effluents of the petroleum industry.