Ana Cláudia Cerqueira

Oil-Refinery Wastewater Treatment Aiming Reuse by Advanced Oxidation Processes (AOPs) Combined with Biological Activated Carbon (BAC)

The treatment of a refinery wastewater by Advanced Oxidation Processes (AOP) coupled with Biological Activated Carbon (BAC) was investigated aiming to generate water for reuse. O3/UV and H2O2/UV processes were employed to oxidize the organic matter and the BAC process to remove residual organic matter from the AOP effluent. AOP promoted oxidation of recalcitrant organic matter as observed by moderate drops on the treated wastewater absorbance (31–79%) and TOC values (10–18%). BAC filters showed to be effective, reaching average efficiencies of 65% in a sufficiently long period of operation (84 days), while GAC filters were saturated after 28 days. Effluent TOC values in the range of 4 to 8.5 mg/L were achieved by the combined treatment (H2O2/UV + BAC), allowing water reuse.

Long-term evaluation of different strategies of cationic polyelectrolyte dosage to control fouling in a membrane bioreactor treating refinery effluent.

ABSTRACT In this article, the long-term use of cationic polyelectrolyte to improve the sludge filterability and to control membrane fouling in bioreactor membrane while treating refinery effluents have been evaluated in pilot scale. Corrective and preventive cationic polyelectrolyte dosages have been added to the membrane bioreactor (MBR) to evaluate the membrane fouling mitigation in both strategies. The results have confirmed that the use of the Membrane performance enhancer (MPE) increased the sludge filterability and reduced the membrane fouling. During the monitoring period, stress events occurred due to the increase in oil and grease and phenol concentrations in the MBR feeds. The preventive use of cationic polyelectrolyte allowed for a more effective and stable sludge filterability, with lower cationic polyelectrolyte consumption and without decreasing MBRs overall pollutant removal performance.

Ageing effect on chlorinated polyethylene membrane of an MBR caused by chemical cleaning procedures

AbstractThe membrane lifetime has a strong influence on the competitiveness and sustainability of Membrane bioreactor (MBR) technology. Membrane replacement is highly expensive operational cost of MBR plants, besides generating residues that have been disposed at municipal landfills or incinerated. Chemical cleaning has been deemed to be one of the most significant factors that shortens membrane lifetime. Chemical cleaning is required to keep the operational flux that is likely to be shortened due to irreversible membrane fouling. This work was aimed to evaluate the influence of chemical agents on chlorinated polyethylene polymeric membrane. Two cleaning procedures were evaluated, namely, (1) cleaning with citric acid followed by sodium hypochlorite (NaOCl) and (2) oxalic acid followed by sodium hypochlorite. After each cleaning cycle, it was determined the membrane permeability. The membranes were also characterized by surface analysis using a scanning electron microscope, thermal resistance by thermogra...

The application of filterability as a parameter to evaluate the biological sludge quality in an MBR treating refinery effluent

AbstractMembrane bioreactors (MBR) have been extensively employed at industrial effluent treatment plants; however the membrane fouling has restrained its more extensive application. Filterability is an important parameter to evaluate sludge properties and the potentiality of membrane fouling in MBR, nevertheless the lack of standardization of its assessment method has made it difficult to understand its actual role on MBR performance and compare its results. In this context, this work aims to compare three filterability assessment methods described in the literature (TTF, FT, and SFI) regarding its capability to sense sludge quality variation and reproducibility, and evaluate the application of this parameter as a tool to monitor and control fouling in MBR treating petroleum refinery effluents. This study showed that, among the methods evaluated, time to filter was the most effective to assess the filterability, both in terms of its capability to sense sludge quality variation and reproducibility. The re...

Toxicity identification and evaluation (TIE) of a petroleum refinery wastewater

ABSTRACT Petroleum refineries generate large amounts of wastewaters, which can have acute/chronic toxicity toward aquatic organisms. Previous studies have shown that many contaminants can be responsible for this toxicity, among them ammonia, sulfide, cyanide, phenols and hydrocarbons. In the study reported herein, the cause of the chronic toxicity of a biotreated petroleum refinery wastewater was investigated by applying the TIE methodology using the microcrustacean Ceriodaphnia dubia. Five samples were analyzed, and the results suggest that copper is the primary toxicant, showing a strong correlation with wastewater toxicity in Phase III. Other metal contaminants, such as zinc and nickel, are present in the samples at toxic concentrations and these may also contribute (to a lesser degree) toward the toxicity. In the case of one sample, the toxicity was attributed to polycyclic aromatic hydrocarbons (PAHs), possibly benzo(a)pyrene, which was present at a concentration toxic to C. dubia. Although the values for the physicochemical parameters of the samples were below Brazilian environmental regulation limits (CONAMA 430), this was not sufficient to prevent chronic toxicity toward aquatic life, indicating that these limits are relatively high.