Eduardo Cleto Pires

Ozone Oxidation of Pulp and Paper Wastewater and its Impact on Molecular Weight Distribution of Organic Matter

The impact of ozone oxidation on removing high molecular weight (HMW) organics in order to improve the biodegradability of alkaline bleach plant effluent was investigated using a semi-batch reactor under different initial pH (12 and 7). After the ozonation process, the ratio of BOD5/COD increased from 0.07 to 0.16 and 0.22 for initial pH 12 and 7, respectively. Also, the effluent color decreased by 48% and 61% at initial pH 12 and pH 7, respectively. These changes were primarily driven by reductions of the HMW fractions of the effluent during ozonation.

Avaliação hidrodinâmica de reator UASB submetido à variação cíclica de vazão

A bench scale UASB reactor (160 l) was used in stimulus-response assays in order to evaluate its behaviour when submitted to cyclical sinusoidal variations of the influent flow rate. Assays were carried out with eosin Y as the tracer in different operational conditions: constant mean influent flow rate of 16 l.h-1 and hydraulic residence time of 10 h (assays 1 and 2), and influent flow rate submitted to sinusoidal variation of 40% (assays 3 and 4) and 60% (assay 5). The variation of tracer concentration in the effluent was adjusted by the theoretical models of dispersion (low and high) and N-continuous stirred tank reactors in series. Complete mixture behaviour was noted to the application of the constant influent flow rate and a plug flow one to the application of the cyclical sinusoidal variations of the influent flow rate. The low dispersion model demonstrated the best mathematical adjustment in the RTD.

Moisture adsorption and desorption behavior of sludge powder.

In this work, the moisture adsorption and desorption isotherms were determined with the aim of defining the range of moisture content for storage of sludge powder. Equilibrium moisture content provides the basis for information not only on how much water has been taken out of a system but also on how fast drying is taking place (drying rate). Once the drying process is accomplished, the main concern rests on the storage of the dried final product. Still, the equilibrium moisture content is valuable information in that it has a major effect on the product physical and chemical properties. The present work also addresses the problem of selecting the best fit for equilibrium moisture content of sludge powder out of six well-known correlations for moisture sorption isotherms of solids: Henderson, Henderson-Thompson, Chung-Pfost, Chen-Clayton, Modified Halsey and Oswin. The equilibrium moisture content was determined by the static method (saturated salt solutions), in which the atmosphere surrounding the product is in equilibrium with the product without mechanical movement of the air or the product. Experiments were carried out under isothermal conditions at 20 and 40 °C. By calculating the regression coefficient, the residuals and the bias measure of Box for the equilibrium moisture content, the study showed that the Oswin Model was the most suitable. The range enclosed within the adsorption isotherm at 40°C and the desorption isotherm at 20°C defines the moisture extremes for storage in most tropical areas of the world.

Poultry slaughterhouse wastewater treatment plant for high quality effluent

This paper assesses a wastewater treatment plant (WWTP) regarding the technology used, as well as organic matter and nutrient removal efficiencies aiming to optimize the treatment processes involved and wastewater reclamation. The WWTP consists of a dissolved air flotation (DAF) system, an upflow anaerobic sludge blanket (UASB) reactor, an aerated-facultative pond (AFP) and a chemical-DAF system. The removal efficiencies of chemical oxygen demand (COD) (97.9 ± 1.0%), biochemical oxygen demand (BOD) (98.6 ± 1.0%) and oil and grease (O&G) (91.1 ± 5.2%) at the WWTP, the nitrogen concentration of 17 ± 11 mg N-NH3 and phosphorus concentration of 1.34 ± 0.93 mg PO4(-3)/L in the final effluent indicate that the processes used are suitable to comply with discharge standards in water bodies. Nitrification and denitrification tests conducted using biomass collected at three AFP points indicated that nitrification and denitrification could take place in the pond.

Media arrangement impacts cell growth in anaerobic fixed-bed reactors treating sugarcane vinasse: Structured vs. randomic biomass immobilization

This study reports on the application of an innovative structured-bed reactor (FVR) as an alternative to conventional packed-bed reactors (PBRs) to treat high-strength solid-rich wastewaters. Using the FVR prevents solids from accumulating within the fixed-bed, while maintaining the advantages of the biomass immobilization. The long-term operation (330days) of a FVR and a PBR applied to sugarcane vinasse under increasing organic loads (2.4-18.0kgCODm-3day-1) was assessed, focusing on the impacts of the different media arrangements over the production and retention of biomass. Much higher organic matter degradation rates, as well as long-term operational stability and high conversion efficiencies (>80%) confirmed that the FVR performed better than the PBR. Despite the equivalent operating conditions, the biomass growth yield was different in both reactors, i.e., 0.095gVSSg-1COD (FVR) and 0.066gVSSg-1COD (PBR), indicating a clear control of the media arrangement over the biomass production in fixed-bed reactors.

Tratamento anaeróbio de pentaclorofenol em reator de leito fluidificado alimentado com água residuária sintética contendo glicose como fonte única de carbono

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% and 70% were obtained for PCP inflow concentrations in the range of 1 to 6mg/l.

Influência da estratificação térmica no volume útil e no comportamento hidrodinâmico de lagoa de estabilização: determinação experimental e teórica

Stabilization ponds located in places that present high temperature variations along the day have a tendency to present thermal stratification, a phenomenon that changes the useful volume of the pond. This paper presents experimental results from two stabilization ponds, facultative and maturation, built in the central area of the state of Sao Paulo, Brazil. The observation of the temperature profile showed the occurrence of thermal stratification with the nictimeral cycle in both ponds. Hydrodynamic tests showed a pattern that resembles the behavior of complete mixing reactors with dead zones, resulting in useful volumes close to 60% for the facultative pond and 30% for the maturation pond. The experiments confirm the theoretical results obtained based on a mathematical model to predict thermal stratification.

Aplicação de indicadores de sustentabilidade para lagoas de estabilização

The choice of an alternative technology for effluent treatment as well as the location for deployment must be preceded by a study of environmental sustainability. A method for assessing the sustainability of wastewater treatment plants, based on environmental, social and economic-financial characteristics was proposed. The method was applied to three wastewater treatment plants using stabilization ponds, located in the municipalities of Cajati, Jacupiranga and Pariquera-Acu, all belonging to the Lower Ribeira de Iguape River basin, in the state of Sao Paulo, Brazil. The lack of values for some parameters considered in the formulation of indicators undermined the achievement of more realistic values. The proposed method proved to be easy to visualize the condition of sustainability of wastewater treatment stations using stabilization ponds.

Determining the distribution of granule diameter from biological sludge

Graphical abstract