Magali Christe Cammarota

Enzymatic pre-hydrolysis and anaerobic degradation of wastewaters with high fat contents

Dairy wastewaters containing elevated fat and grease levels (868 mg l−1) were treated in an upflow anaerobic sludge blanket reactor (UASB) and resulted in effluents of high turbidity (757 nephelometric turbidity units), volatile suspended solids up to 944 mg l−1 and COD removal below 50%. When the same dairy wastewater was pre-treated with 0.1% (w/v) of fermented babassu cake containing Penicillium restrictum lipases, turbidity and volatile suspended solids were decreased by 75% and 90%, respectively, and COD removal was as high as 90%.

Metabolic blocking of exopolysaccharides synthesis : effects on microbial adhesion and biofilm accumulation

A blocking agent of polysaccharide synthesis (5 x 10-4 M 2,4-dinitrophenol) was continuously added to a reaction system, where a heterogeneous microbial population was cultivated at a dilution rate of 0.1 h-1. The results indicate that adhesion and biofilm accumulation were severely reduced when exopolysaccharydes synthesis was blocked.

Slaughterhouse wastewater treatment: evaluation of a new three-phase separation system in a UASB reactor

The anaerobic treatment of the wastewater from the meat processing industry was studied using a 7.2 1 UASB reactor. The reactor was equipped with an unconventional configuration of the three-phase separation system. The effluent was characterized in terms of pH (6.3-6.6), chemical oxygen demand (COD) (2,000-6,000 mg l(-1)), biochemical oxygen demand BOD5 (1,300-2,300 mg 1(-1)), fats (40-600 mg l(-1)) and total suspended solids (TSS) (850-6,300 mg l(-1)) The reactor operated continuously throughout 80 days with hydraulic retention time of 14, 18 and 22 h. The wastewater from Rezende Industrial was collected after it had gone through pretreatment (screening, flotation and equalization). COD, BOD and TSS reductions and the biogas production rate were the parameters considered in analyzing the efficiency of the process. The average production of biogas was 111 day(-1) (STP) for the three experimental runs. COD removal varied from 77% to 91% while BOD removal was 95%. The removal of total suspended solids varied from 81% to 86%. This fact supports optimal efficiency of the proposed three-phase separation system as well as the possibility of applying it to the treatment of industrial effluents.

HYDROLYTIC ENZYMES AS COADJUVANTS IN THE ANAEROBIC TREATMENT OF DAIRY WASTEWATERS

An enzymatic extract produced by Penicillium restrictum having a high level of lipase activity (17.2 U.g-1) was obtained by solid-state fermentation using babassu cake as substrate. The enzymatic extract was used in the hydrolysis of a dairy wastewater with high fat contents (180, 450, 900 and 1,200 mg.L-1). Different hydrolysis conditions were tested, and it was determined that it should be carried out at a temperature of 35oC, without agitation, with 10% v/v enzymatic extract and a hydrolysis time of 12 hours. Both crude and hydrolysed effluents were then submitted to an anaerobic biological treatment. It was observed that for the enzymatically pretreated effluent there was a significant improvement in the efficiency of the anaerobic treatment. For the highest fat content tested (1,200 mg.L-1), removal efficiencies of 19 and 80% were attained for crude and hydrolysed effluents, respectively. In addition, a tenfold increase in the removal rate of COD from the hydrolysed effluent (1.87 kg COD.m-3.d-1) was observed in relation to the crude effluent (0.18 kg COD.m-3.d-1). The results obtained in this study illustrate the viability of using a hybrid treatment (enzymatic-biological) for wastewaters having high fat contents.

Biological treatment of oil field wastewater in a sequencing batch reactor.

This work reports the results of experiments carried out in a sequencing batch reactor (SBR) operated under 24 hour cycles, treating an effluent containing a mixture of oil field wastewater and sewage, in different percentages. The removal of phenols, ammonium and COD was monitored in several experimental runs, varying the dilution degree of the oilfield wastewater (10 to 45% v/v). The volatile suspended solids (VSS) content in the reactor was also monitored and the protein (PTN) and polysaccharide (PS) contents of the suspended biomass were determined. The removal of ammonium and phenols did not vary significantly in the experimental runs, attaining average values of 95% and 65%, respectively. COD removal efficiencies in the range of 30 to 50% were attained in the experiments carried out with dilution percentages of 45 and 35% (v/v) respectively. An experiment carried out with a lower proportion of produced water (15% v/v), keeping the salinity level corresponding to a higher proportion of industrial effluent (45% v/v), led to an improvement in the COD removal, indicating that the recalcitrance of the organic compounds found in the effluent is the main cause of the moderate COD removal efficiencies attained in the SBR system. With regard to the composition of the microbial flocs, no significant variation was observed in the PS/PTN, PS/VSS and PTN/VSS ratios when the effluent composition changed (increased salinity and levels of organic material).

Decolorization of Dyes from textile wastewater by Trametes versicolor

The white rot fungus Trametes versicolor was applied to the decolourisation of three synthetic textile dyes in the presence and absence of glucose. Different initial dye concentrations were tested and approximately 97% decolourisation was achieved. It was found that fungal metabolism induced by the glucose as well as the pH play an important role in the decolourisation process. This treatment was also applied to a real wastewater from a textile industry-dyeing sector leading to 92% decolourisation.

Phenol removal through combined biological and enzymatic treatments

This work studies the use of biological and combined biological/enzymatic treatments in phenol degradation. The systems studied were conventional batch aerobic biological followed or preceded by enzymatic treatment. Tyrosinase extracted from the mushroom Agaricus bispora was employed. Biological treatment efficiently degraded effluents containing up to 420 mg.L-1 of phenol, removing 97% of the COD and 99% of the phenol in 48-hour batches. Alterations in phenol concentration intake reduced treatment efficiency significantly. Enzymatic polishing of biotreated effluent removed up to 75% of the remaining phenol in a four-hour reaction with 46 U.mL-1 of tyrosinase and 50 mg.L-1 of chitosan (used as coagulant). Enzymatic pretreatment with 20 U.mL-1 of tyrosinase reduced the phenol concentration by 25 % after 2 hours of reaction, although initial COD increased up to 58%. The subsequent biological treatment of that enzymatic pretreated effluent reduced COD to 151 mgO2.L-1 and phenol concentration to 1 mg.L-1 in 24-hours batches.

Impact of enzymatic pre-hydrolysis on batch activated sludge systems dealing with oily wastewaters

Dairy wastewater containing different oil and grease contents was treated in batch activated sludge systems with and without (control) an enzymatic pre-hydrolysis stage [with 0.2% (w/v) of fermented babassu cake containing Penicillium restrictum lipases]. When the oil and grease concentration in the control bioreactor was increased (400, 600 and 800 mg l−1), the COD removal efficiency fell (86%, 75% and 0%). However, in the reactor fed with pre-hydrolysed wastewater, COD removal efficiency was maintained (93%, 92% and 82%). At an oil and grease concentration of 800 mg l−1, the control bioreactor presented final volatile suspended solids (VSS) values ten times greater (2225 mg l−1) than those obtained for bioreactor fed with pre-hydrolysed wastewater (200 mg l−1).

Performance and molecular evaluation of an anaerobic system with suspended biomass for treating wastewater with high fat content after enzymatic hydrolysis.

The effect of a lipase-rich fungal enzymatic preparation, produced by a Penicillium sp. during solid-state fermentation, was evaluated in an anaerobic digester treating dairy wastewater with 1200 mg of oil and grease/L. The oil and grease hydrolysis step was carried out with 0.1% (w/v) of solid enzymatic preparation at 30 degrees C for 24 h, and resulted in a final free acid concentration eight times higher than the initial value. The digester operated in sequential batches of 48 h at 30 degrees C for 245 days, and had high chemical oxygen demand (COD) removal efficiencies (around 90%) when fed with pre-hydrolyzed wastewater. However, when the pre-hydrolysis step was removed, the anaerobic digester performed poorly (with an average COD removal of 32%), as the oil and grease accumulated in the biomass and effluent oil and grease concentration increased throughout the operational period. PCR-DGGE analysis of the Bacteria and Archaea domains revealed remarkable differences in the microbial profiles in trials conducted with and without the pre-hydrolysis step, indicating that differences observed in overall parameters were intrinsically related to the microbial diversity of the anaerobic sludge.

Evaluation of pH, alkalinity and temperature during air stripping process for ammonia removal from landfill leachate

The objective of this research was to evaluate the air stripping technology for the removal of ammonia from landfill leachates. In this process, pH, temperature, airflow rate and operation time were investigated. Furthermore, the relationship between the leachate alkalinity and the ammonia removal efficiency during the process was studied. The leachate used in the tests was generated in the Gramacho Municipal Solid Waste Landfill (Rio de Janeiro State, Brazil). The best results were obtained with a temperature of 60oC, and they were independent of the pH value for 7 h of operation (the ammonia nitrogen removal was greater than 95%). A strong influence of the leachate alkalinity on the ammonia nitrogen removal was observed; as the alkalinity decreased, the ammonia concentration also decreased because of prior CO2 removal, which increased the pH and consequently favored the NH3 stripping. The air flow rate, in the values evaluated (73, 96 and 120 L air.h−1. L−1 of leachate), did not influence the results.