Tomasz Jóźwiak

Municipal landfill leachate nitrification in RBC biofilm - process efficiency and molecular analysis of microbial structure.

Landfill leachates were treated using a two-stage rotating biological contactor (RBC). At an ammonium load of 1.92gN-NH(4)/m(2)d, complete nitrification was obtained at the first stage; however, at a higher load (3.6gN-NH(4)/m(2)d) a two-stage system was needed to obtain complete nitrification. A further increase in the ammonium load to 4.79gN-NH(4)/m(2)d and 6.63gN-NH(4)/m(2)d caused a decrease of overall nitrification efficiency to 74.4% and 71.6%, respectively. Randomly amplified DNA analysis of bacteria present in the RBC revealed that the bacterial community differed over time. Regardless of the ammonium load, Nitrosomonas europaea and Nitrosomonas eutropha were the dominating species. The performed analyses provide a clear picture of bacterial population changes in response to changes of ammonium load during landfill leachate treatment.

Application of chemically-cross-linked chitosan for the removal of Reactive Black 5 and Reactive Yellow 84 dyes from aqueous solutions

Abstract The study analyzed the sorption effectiveness of reactive dyes, Reactive Black 5 (RB5) and Reactive Yellow 84 (RY84), onto non-cross-linked chitosan beads (CHs) and onto CHs cross-linked with glutaraldehyde (ALD) i.e., ALD-CHs and epichlorohydrin (ECH) i.e., ECH-CHs. The study enabled determination of the optimal ratio of the cross-linking agent to chitosan and the optimal pH of the sorption process (from the range of 1:10–10:1, to 2–12, respectively). The time needed to reach the equilibrium concentration reached 504 h. Satisfactory effects of RB5 and RY84 sorption were achieved after 24 h sorption. Data were described with the heterogenous Langmuir’s model (double Langmuir’s equation). For RB5 dye, the most effective sorbent turned out to be CHs – the maximum sorption capacity reached 2025.11 (mg/g). For the other sorbents, ALD-CHs and ECH-CHs, the capacity accounted for 1797.0 mg/g and 1816.1 mg/g, respectively. In the case of RY84 dye, the most effective sorbent appeared to be ECH-CHs – 2234.3 mg/g. For CHs and ALD-CHs, the highest sorption capacities against RY84 reached 1774.2 and 2000.1 mg/g, respectively.

Effect of the C:N:P ratio on the denitrifying dephosphatation in a sequencing batch biofilm reactor (SBBR)

A series of investigations were conducted using sequencing batch biofilm reactor (SBBR) to explore the influence of C:N:P ratio on biological dephosphatation including the denitrifying dephosphatation and the denitrification process. Biomass in the reactor occurred mainly in the form of a biofilm attached to completely submerged disks. Acetic acid was used as the source of organic carbon. C:N:P ratios have had a significant effect on the profiles of phosphate release and phosphate uptake and nitrogen removal. The highest rates of phosphate release and phosphate uptake were recorded at the C:N:P ratio of 140:70:7. The C:N ratio of 2.5:1 ensured complete denitrification. The highest rate of denitrification was achieved at the C:N:P ratio of 140:35:7. The increase of nitrogen load caused an increase in phosphates removal until a ratio C:N:P of 140:140:7. Bacteria of the biofilm exposed to alternate conditions of mixing and aeration exhibited enhanced intracellular accumulation of polyphosphates. Also, the structure of the biofilm encouraged anaerobic-aerobic as well as anoxic-anaerobic and absolutely anaerobic conditions in a SBBR. These heterogeneous conditions in the presence of nitrates may be a significant factor determining the promotion of denitrifying polyphosphate accumulating organism (DNPAO) development.

Effect of the form and deacetylation degree of chitosan sorbents on sorption effectiveness of Reactive Black 5 from aqueous solutions

The article presents the impact of a chitosan sorbent form (flakes/hydrogel granules) and the degree of its deacetylation (DD=75%/DD=85%/DD=90%) on the effectiveness of sorption of a popular textile dye Reactive Black 5 (RB5). The effect of pH on dye sorption effectiveness was examined as well as RB5 sorption kinetics and RB5 sorption capacity of the chitosan sorbent were tested. The highest sorption capacity (1559.7mg/g) was obtained for the chitosan hydrogel in the form of granules (DD=90%). Due to a loose structure and an easy access to sorption centers, chitosan hydrogel granules may ensure up to 224% higher sorption capacity (QDD75%=1307.5mg/g) than chitosan in the form of flakes (QDD75%=403.4mg/g). The sorption effectiveness of the tested dye was observed to increase in the range of DD=75%<DD=85%<DD=90%. The deacetylation degree of chitosan had a particularly large impact on RB5 sorption effectiveness by chitosan in the form of flakes. The effectiveness of adsorption on the flakes with a deacetylation degree DD=90% was 1049.6mg/g and was by 160% higher than on the flakes with DD=75%.

The use of cross-linked chitosan beads for nutrients (nitrate and orthophosphate) removal from a mixture of P-PO4, N-NO2 and N-NO3

A hydrogel chitosan sorbent ionically cross-linked with sodium citrate and covalently cross-linked with epichlorohydrin was used to remove nutrients from an equimolar mixture of P-PO4, N-NO2 and N-NO3. The scope of the study included, among other things, determination of the influence of pH on nutrient sorption effectiveness, nutrient sorption kinetics as well as determination of the maximum sorption capacity of cross-linked chitosan sorbents regarding P-PO4 (H2PO4-, HPO42-), N-NO2 (HNO2, NO2-), and N-NO3 (NO3-). The effect of the type of the cross-linking agent on the affinity of the modified chitosan to each nutrient was studied as well. The kinetics of nutrient sorption on the tested chitosan sorbents was best described with the pseudo-second order model. The model of intramolecular diffusion showed that P-PO4, N-NO2 and N-NO3 sorption on cross-linked hydrogel chitosan beads proceeded in two phases. The best sorbent of nutrients turned out to be chitosan cross-linked covalently with epichlorohydrin; with P-PO4, N-NO2 and N-NO3 sorption capacity reaching: 1.23, 0.94 and 0.76mmol/g, respectively (total of 2.92mmol/g). For comparison, the sorption capacity of chitosan cross-linked ionically with sodium citrate was: 0.43, 0.39 and 0.39mmol/g for P-PO4, N-NO2 and N-NO3, respectively (total of 1.21mmol/g).

Application of biosurfactants for heavy netals leaching from immobilized activated sludge / Zastosowanie biosurfaktantów do wymywania metali ciężkich z immobilizowanego osadu czynnego

Abstract This study was undertaken to determine the effectiveness of biosurfactants - saponin, tannin and rhamnolipids JBR 515 and 425, for the removal of cadmium, zinc and copper from activated sludge immobilized in 1.5% sodium alginate with 0.5% polyvinyl alcohol. We also established the impact of pH value on biosorbent regeneration with the analyzed biosurfactants and determined the critical micelle concentration (CMC) in solutions containing the biosorbent and biosurfactant and in exact samples with heavy metals. Saponin exhibited the highest effectiveness of metals leaching at pH 1-5, and rhamnosides at pH 5-6. In addition, the study demonstrated a significant effect of the ratio of biosorbent mass to washing agent volume (m/V) on the effectiveness of metals leaching. Of the biosurfactants analyzed, saponin was ca. 100% effective in leaching zinc and copper. The effectiveness of the other biosurfactants was lower and depended on the metal being leached W pracy podjęto badania nad określeniem efektywności wykorzystania biosurfaktantów - saponiny, taniny oraz ramnolipidów JBR 515 i JBR 425 do wymywania kadmu, cynku i miedzi z osadu czynnego immobilizowanego w alginianie sodu 1,5% z alkoholem poliwinylowym 0,5%. Przeprowadzone badania pozwoliły określić wpływ odczynu na regenerację biosorbentu za pomocą testowanych biosurfaktantów, wyznaczyć krytyczne stężenie micelarne (CMC) w roztworach zawierających biosorbent i biosurfaktant oraz w próbach właściwych z metalami ciężkimi. Saponina charakteryzowała się najwyższą efektywnością wymywania metali przy pH 1-5, a ramnolipidy przy pH 5-6. Ponadto badania wykazały istotny wpływ stosunku masy biosorbentu do objętości eluatu (m/V) na skuteczność wymywania metali. Spośród analizowanych biosurfaktantów saponina wykazywała około 100% efektywność usuwania z biosorbentu cynku i miedzi. Skuteczność innych biosurfaktantów była niższa i zależała od rodzaju metalu

Phosphate removal from aqueous solutions by chitin and chitosan in flakes

The article presents the effectiveness of phosphate adsorption on the flakes of chitin and chitosan. Studies performed determined adsorption capacity of chitin and chitosan, best among the tested adsorption pH and the equilibrium time. Langmuir model was used to describe the results. The highest removal efficiency of phosphorus compounds using chitin was obtained at pH 3 and with chitosan at pH 4. The study of phosphate equilibrium concentration time obtained for both sorbents was carried out at three concentrations of 1, 5 and 10 mg/dm. The highest sorption efficiency of the phosphate using chitin was achieved after 20 minutes of the process and at the chitosan after 40 minutes. In the case of chitosan after the equilibrium time the effect of partial P-PO4 release was observed, which could be related to the change in pH of the solution by the sorbent. Studies have shown that chitosan is a more effective absorbent for phosphorus compounds. The maximum adsorption capacity of chitosan with phosphate was 6.65 mg/g, and chitin 2.09 mg/g.

Effect of conditions of air-lift type reactor work on cadmium adsorption

We investigated cadmium sorption by activated sludge immobilized in 1.5% sodium alginate with 0.5% polyvinyl alcohol. Experiments were conducted in an air-lift type reactor at the constant concentration of biosorbent reaching 5 d.m./dm3, at three flow rates: 0.1, 0.25 and 0.5 V/h, and at three concentrations of the inflowing cadmium solution: 10, 25 and 50mg/dm3. Analyses determined adsorption capacity of activated sludge immobilized in alginate as well as reactor’s work time depending on flow rate and initial concentration of the solution. Results achieved were described with the use of Thomas model. The highest adsorption capacity of the sorbent (determined from the Thomas model), i.e., 200.2 mg/g d.m. was obtained at inflowing solution concentration of 50 mg/dm3 and flow rate of 0.1 V/h, whereas the lowest one reached 53.69 mg/g d.m. at the respective values of 10 mg/dm3 and 0.1 V/h. Analyses were also carried out to determine the degree of biosorbent adsorption capacity utilization at the assumed effectiveness of cadmium removal — at the breakthrough point (C=0.05*C0) and at adsorption capacity depletion point (C-0.9*C0). The study demonstrated that the effectiveness of adsorption capacity utilization was influenced by both the concentration and flow rate of the inflowing solution. The highest degree of sorbent capacity utilization was noted at inflowing solution concentration of 50 mg/dm3 and flow rate of 0.1 V/h, whereas the lowest one at the respective values of 10 mg/dm3 and 0.1 V/h. The course of the process under dynamic conditions was evaluated using coefficients of tangent inclination — a, at point C/C0=½. A distinct tendency was demonstrated in changes of tangent slope a as affected by the initial concentration of cadmium and flow rate of the solution. The highest values of a coefficient were achieved at the flow rate of 0.1 V/h and initial cadmium concentration of 50 mg/dm3.

Cyclical metal adsorption and desorption through sludge immobilized in chitosan media

In this research, a cyclical adsorption/desorption of cadmium and zinc from solutions containing a single metal or its mixture in ratio of 1:1 and 1:2 using immobilized activated sludge in the chitosan (ASC) was examined. In the adsorption studies, the optimal dose of ASC was 4 g/L. The highest desorption efficiency was achieved for 1M HNO3. Both adsorption and desorption occurred in accordance with a pseudo-second order reactions which is confirmed by R values. Mass of zinc adsorbed and desorbed in one cycle from a solution containing a single metal was 0.78 and 0.40 mmol/g d.w. when cadmium was lower (respectively 0.41 and 0.21 mmol/g d.w.). In subsequent cycles, both metals were adsorbed and desorbed at a lower efficiency. The highest efficiency of desorption was observed for a mixture of Cd:Zn in the ratio of 1:1 and 1:2, respectively 86% and 89% of cycle1, whereas for the zinc it was 70% and 53%. Desorption efficiency of both metals and its mixtures, in subsequent cycles gradually decreased.

The Use of Coconut Shells for the Removal of Dyes from Aqueous Solutions

The main purpose of the work was to check the possibility of using coconut shells for the removal of the dyes popular in the textile industry from aqueous solutions. The sorption abilities of an unconventional sorbent were tested against four anionic dyes: Reactive Black 5, Reactive Yellow 84, Acid Yellow 23, Acid Red 18 as well as two cationic dyes: Basic Violet 10 and Basic Red 46. The scope of research included investigation pertaining to the effect of pH on the effectiveness of sorption of dyes, conducted in order to determine the time of equilibrium of sorption and determine the maximum sorption capacity of coconut shells with respect to pigments. The most favorable pH of sorption for the anionic dyes and Basic Violet 10 was pH 3 and for Basic Red 46 – pH 6. The equilibrium time of sorption was the shortest in the case of acidic dyes (Acid Yellow 23/ Acid Red 18 – 45 min), while the longest in the case of alkaline dyes (Basic Red 46 – 90 min, Basic Violet 10 – 180 min). The sorption capacity of coconut shells in relation to anionic dyes was for Reactive Black 5 – 0.82 mg/g, Reactive Yellow 84 – 0.96 mg/g, Acid Yellow 23 – 0.53 mg/g and for Acid Red 18 – 0.66 mg/g. The tested sorbent showed much higher sorption capacity with respect to the cationic dyes, i.e. Basic Violet 10 (28.54 mg/g) and Basic Red 46 (68.52 mg/g).