Dilcemara Cristina Zenatti

Anaerobic co-digestion of crude glycerin and starch industry effluent

The Brazils Biodiesel Production and Use Program introduces biodiesel in the Brazilian energy matrix, bringing along the perspective of a growth of the glycerin offer, co-product generated in the proportion of 10 kg for each 100 L of biodiesel. The aim of this study was to evaluate the addition of crude glycerin in the anaerobic digestion of cassava starch industry effluent (cassava wastewater), in a horizontal semi-continuous flow reactor of one phase in laboratory scale. It was used a reactor with a 8.77 L of useful volume, a medium support for corrugated conduit of polyvinyl chloride (PVC), temperature of 261 oC, fed with cassava wastewater and glycerin, with hydraulic detention times of 4 and 5 days and increasing volumetric organic load of 3.05; 9.32; 14.83 and 13.59 g COD L-1 d-1, obtained with the addition of glycerin at 0; 2; 3 and 2% (v/v), respectively. The average removal efficiencies of TS and TVS were decreasing from the addition of glycerin to the cassava wastewater, averaging 81.19 to 55.58% for TS and 90.21 to 61.45% for TVS. The addition of glycerin at 2% increased the biogas production compared to the control treatment, reaching 1.979 L L-1 d-1. The biogas production as a function of the consumed COD was higher for the control treatment than for the treatments with addition of glycerin, which indicates lower conversion of organic matter into biogas.

Selection of microorganisms producer of lipase for fat removal from biodiesel purification water

The objective this study has been the selection of lipase productor microorganism, for removal of oils and grease, in the pre-treatment of biodiesel wastewater washing. For this, analyses of the physicist-chemistries characteristics had been made with the wastewater of the biodiesel washing, and then it had been isolated and chosen, by means of determinations of the lipase activity. Following, it was made a test of fat biodegradation, in the conditions: pH (5.95), temperature (35 oC), rotation (180 rpm) and ammonium sulfate as nitrogen source (3 g L-1) and establishing as variable the two microorganism preselected and the time (24; 48; 72; 96 and 120 h). The biodiesel purification wastewater had presented high potential of environmental impact, presenting a concentration of O of 6.76 g L-1. From the six isolated microbiological cultures, two microorganisms (A and B) had been selected, with enzymatic index of 0.56 and 0.57, respectively. The treatment of the wastewater using the isolated microorganism (Klebsiella oxytoca) had 80% of the fatty removal in 48 h.

Nitrificação de efluente de abatedouro de tilápia em função da aeração e tempo de reação

The occurrence of composts of nitrogen above the legal limits has been causing serious pollution problems in water receptor bodies. The biological process for removal of these substances commonly found in the ammoniacal nitrogen form is known as nitrification. The present study had as its objective the evaluation of the effects of the reaction time (TR) and of the aeration on the removal efficiency of the ammoniacal nitrogen and on the conversion of the ammoniacal nitrogen to nitrate in a nitrification process of the tilapia slaughterhouse effluent in sequential batch reactor with biofilm. The experiment was performed using two reaction times (6 and 12 h) and two levels of air flow (3 and 6 L min-1), four treatments, starting from the combination of these two variables, were evaluated in an experimental planning of the factorial 22 type: being: T4 (QAr = 3 L min-1 and TR = 6); T2 (QAr = 6 L min-1 and TR = 6), T3 (QAr = 3 L min-1 and TR = 12) and T1 (QAr = 6 L min-1 and TR = 12), and four repetitions. The most significant results were obtained for treatment T4, where the efficiency for conversion of the ammoniacal nitrogen to nitrate obtained was 57.27 ± 27.05 and removal of the ammoniacal nitrogen was 81.90% ± 3.80.

Removal of silver nanoparticles coated with different stabilizers from aqueous medium by electrocoagulation

ABSTRACT This study evaluated the removal of silver nanoparticles (AgNPs), coated with different stabilizers, from aqueous media using the electrocoagulation technique. The AgNPs dispersions were synthesized by chemical reduction with silver nitrate as precursor, sodium borohydride as reducing agent and sodium carboxymethylcellulose (CMC), polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP) as stabilizers with initial concentrations of 1 and 3% (w/v). The dispersions were named AgNPs-CMC1, AgNPs-CMC3, AgNPs-PVA1, AgNPs-PVA3, AgNPs-PVP1, and AgNPs-PVP3. Electrocoagulation treatments of AgNPs-PVA1, AgNPs-PVP1 and AgNPs-PVP3 dispersions resulted in total silver removals above 99.90% in 10 min. For the AgNPs-PVP3 dispersion 99.98% of removal was obtained in 20 min. After 15 min of electrolysis, The AgNPs-CMC1 and AgNPs-CMC3 dispersions showed a reduction in total silver concentration of 71.72 and 52.15%, respectively. Therefore, these results showed that the removal of AgNPs from the aqueous medium by electrocoagulation is possible, but their efficiency and viability depends on the nature, the molecular structure and the concentration of stabilizers. Furthermore, the toxicity analysis using the Vibrio fischeri bacteria demonstrated that only the dispersions stabilized with PVP became suitable for disposal after the electrocoagulation treatment. GRAPHICAL ABSTRACT