Removal of disperse dyes from textile wastewater using bio-sludge

Granular activated carbon (GAC) did not show any significant adsorption ability on the disperse dyes, while resting (living) bio-sludge of a domestic wastewater treatment plant showed high adsorption abilities on both disperse dyes and organic matter. The dye adsorption ability of bio-sludge increased by approximately 30% through acclimatization with disperse dyes, and it decreased by autoclaving. The deteriorated bio-sludge could be reused after being washed with 0.1N NaOH solution. Disperse Red 60 was more easily adsorbed onto the bio-sludge than Disperse Blue 60. The Disperse Red 60, COD, and BOD5 adsorption capacities of acclimatized, resting bio-sludge were 40.0+/-0.1, 450+/-12, and 300+/-10mg/g of bio-sludge, respectively. The GAC-SBR system could be applied to treat textile wastewater (TWW) containing disperse dyes with high dye, BOD5, COD, and TKN removal efficiencies of 93.0+/-1.1%, 88.0+/-3.1%, 92.2+/-2.7% and 51.5+/-7.0%, respectively without any excess bio-sludge production under an organic loading of 0.18 kg BOD5/m3-d. Furthermore, the removal efficiencies increased with the addition of glucose into the system. The dye, BOD5, COD, and TKN removal efficiencies of the GAC-SBR system with TWW containing 0.89 g/L glucose were 94.6+/-0.7%, 94.4+/-0.6%, 94.4+/-0.8% and 59.3+/-8.5%, respectively, under an SRT of 67+/-0.4 days.     

Decolorization of molasses wastewater by Lactobacillus plantarum No. PV71-1861

Lactobacillus plantarum No. PV71-1861, isolated from pickle samples in Thailand, showed the high potential for use in decolorization of molasses wastewater under both anaerobic and facultative (static) conditions. The strain showed the highest melanoidin pigment (MP) decolorization yield of 68.12% with MP solution (color intensity corresponding to an optical density of 3.5 units at 475 nm) containing 2% glucose, 0.4% yeast extract, 0.1% KH(2)PO(4), 0.05% MgSO(4).7H(2)O and initial pH of 6 under static condition at 30 degrees C within 7 days. But, it showed low growth and MP decolorization yields under aerobic conditions. Gel filtration chromatograms of the MP solutions showed that the small molecular weight fraction of MP solution was decolorized by the strain when the large molecular weight fraction still remained in the effluent. For application, the strain could apply to treat anaerobic treated-molasses wastewater (T-MWW) with high removal efficiency. The highest MP removal efficiencies and growth yield of 76.6% and 2.6 mg/mL, respectively, were observed with the T-MWW within 7 days of culture, and the effluent pH of the system was decreased to lower than 4.0 after 2-3 days operation.     

Feasibility of using constructed wetland treatment for molasses wastewater treatment

The surface flow constructed wetland (SFCW) with Cyperus involucratus, Typha augustifolia and Thalia dealbata J. Fraser was applied to treat anaerobic treated-molasses wastewater (An-MWW) under the organic loading rates (OLRs) of 612, 696, 806, 929 and 1,213 kg BOD(5)ha(-1)day(-1). The results showed that both removal efficiency and plant growth rate were increased with the decrease of organic loading rate (OLR). All tested-plant species could not grow under OLR of higher than 696 kg BOD(5)mg l(-1) (p>0.05). Also, the plant-biomass of the systems was reduced by 10.4%, 26.5%, and 64.7% of initial plant-biomass under the OLR of 806, 929 and 1,213 kg BOD(5)ha(-1)day(-1), respectively. However, all tested-plant species showed the same pattern on the plant-biomass production yield and removal efficiency. The highest SS, BOD, COD, total phosphorus, NH(4)(+), NO(3)(-) and molasses pigments (MP) removal efficiencies of 90-93%, 88-89%, 67%, 70-76%, 77-82%, 94-95% and 72-77%, respectively were detected under the OLR of 612 kg BOD(5)ha(-1)day.     

Seafood wastewater treatment in constructed wetland: tropical case

A series of investigations were conducted to evaluate the feasibility of using constructed wetlands to remove pollutants from seafood processing wastewater. Six emergent plant species; Cyperus involucratus, Canna siamensis, Heliconia spp., Hymenocallis littoralis, Typha augustifolia and Thalia deabata J. Fraser were planted in surface flow wetland. They were fed with seafood wastewater that was 50% diluted with treated seafood wastewater from an aerated lagoon. All macrophytes were found to meet satisfying treatment efficiency (standard criteria for discharged wastewater) at 5 days hydraulic retention time (HRT). While C. involucratus, T. deabata and T. augustifolia met acceptable treatment efficacy at 3 days HRT. Nutrient uptake rate of these species was observed in the range of 1.43-2.30 g Nitrogen/m(2)day and 0.17-0.29 g Phosphorus/m(2)day, respectively at 3 days HRT. The highest treatment performances were found at 5 days HRT. Average removal efficiencies were 91-99% for BOD(5), 52-90% for SS, 72-92% for TN and 72-77% for TP. Plant growth and nitrogen assimilation were experienced to be most satisfactory for C. involucratus, T. deabata and T. augustifolia. Lower HRTs affected contaminant removal efficiency for all species. C. involucratus, T. deabata and T. augustifolia can remove all contaminants efficiently even at the lowest hydraulic retention time (1 day).     

Treatment of molasses wastewater by acetogenic bacteria BP103 in sequencing batch reactor (SBR) system

Acetogenic bacteria BP103 cells could be used as the absorbent for melanoidin pigment (MP) and molasses wastewater (MWW). The maximum MP adsorption yield of this strain observed from the dead (autoclaved) cell. It was two times higher than that with resting cells. However, the MP adsorption yield of the strain was 50-60% decreased by acclimatization with the media containing MP. The deteriorated cells (MP-adsorbed cells) could be recovered by washing with 0.1% SDS, 0.1% Tween 80 and 0.1 mol/L NaOH solutions. Among them, 0.1 mol/L NaOH solution was most suitable according to highest elution ability and no-effect to the MP adsorption capacity (The adsorption yield of deteriorated cell was reduced only 10% after washing three times with 0.1 mol/L NaOH solution). In SBR system, the strain showed very low MP removal yield with both molasses wastewater (MWW) from the anaerobic pond (An-MWW) and stillage from an alcohol factory (U-MWW). However, the MP removal yield was increased by supplementation with carbon sources (glucose). Also, the MP removal efficiency was increased with the increase of supplemented-glucose concentration. The highest COD, BOD(5), TKN and MP removal efficiencies of the SBR system with 10 times-diluted An-MWW solution containing 30 g/L glucose under HRT of seven days were 65.2+/-2.5%, 82.8+/-3.4%, 32.1+/-0.8% and 50.2+/-3.7%, respectively. The large molecular weight fraction of MP in both U-MWW and An-MWW solutions were rapidly removed by acetogenic bacteria BP103, while the small molecular weight fractions of MP still remained in the effluent.     

Packed cage rotating biological contactor system for treatment of cyanide wastewater

The aim of this work was to study the efficiency of the packed cage rotating biological contactor (RBC) system with synthetic wastewater (SWW) containing 800 mg/l BOD(5) with various cyanide residue concentrations and hydraulic loading time. The results showed that cyanide had a negative effect to both the system's efficiency and bio-film quality. An increase in cyanide concentration led to a decrease in bio-film growth and the consequent reduction in the removal efficiency of the system. Also, the effluent suspended solids (SS) of the system was increased with increasing cyanide concentrations because the bio-film detached from the media due to the toxicity of the cyanide residue. The system showed the highest COD, BOD(5), TKN and cyanide removal efficiencies of 94.0 +/- 1.6%, 94.8 +/- 0.9%, 59.1 +/- 2.8% and 95.5 +/- 0.6%, respectively, with SWW containing 5 mg/l cyanide under HRT of 8 days, while they were only 88.8 +/- 0.7%, 89.5 +/- 0.5%, 40.3 +/- 1.1% and 93.60 +/- 0.09%, respectively, with SWW containing 40 mg/l cyanide. In addition, the effluent ammonia, nitrite and nitrate were increased with increases in cyanide concentration or loading. However, the system with SWW containing the highest cyanide concentration of 40 mg/l showed almost constant COD and BOD(5) removal efficiencies of 89% and 90%, even when the system was controlled under the lowest HRT of 8 h.     

Removal of Zn2+ and Cu2+ by a sequencing batch reactor (SBR) system

Both resting (living) and autoclaved (dead) bio-sludges showed almost the same Cu2+ and Zn2+ adsorption capacities with synthetic industrial estate wastewater (SIEWW). The resting bio-sludge showed not only Cu2+ and Zn2+ adsorption abilities but also organic matter adsorption ability. But, the organic matter (COD and BOD5) adsorption ability of bio-sludge with SIEWW containing 60 mg/L Cu2+ was about half of that with SIEWW containing 60 mg/L Zn2+. The adsorbed Cu2+ and Zn2+ were easily eluted (70-75%) from bio-sludge with 0.1 N HNO3 and 0.1 M EDTA solutions. Bio-sludge from a wastewater treatment plant could be used as an adsorbent for metal ions (Cu2+ and Zn2+). Cu2+ and Zn2+ could repress the SBR system efficiency but its efficiency could be increased with the increase of mixed liquor suspended solids (MLSS), and Cu2+ had more effect than Zn2+ to repress the system efficiency. The SBR system showed very low removal efficiencies of the pollutants with industrial estate wastewater (IEWW), but its pollutant removal efficiencies with IEWW could be increased with the addition of glucose. The Zn2+, Cu2+, BOD5, COD and TKN removal efficiencies of the system with IEWW containing 1.27 g/L glucose, 10 mg/L Cu2+ and 10 mg/L Zn2+ under MLSS of 4500 mg/L were 92.61 +/- 0.28%, 83.77 +/- 0.93%, 98 +/- 0%, 92 +/- 0% and 78.1 +/- 0.1%, respectively.     

Removal of Pb2+ and Ni2+ by bio-sludge in sequencing batch reactor (SBR) and granular activated carbon-SBR (GAC-SBR) systems

Living bio-sludge from domestic wastewater treatment plant was used as adsorbent of heavy metals (Pb(2+), Ni(2+)) and its adsorption capacity was about 10-30% reduced by autoclaving at 110 degrees C for 10 min. The living bio-sludge acclimatized in synthetic industrial estate wastewater (SIEWW) without heavy metals showed the highest Pb(2+) and Ni(2+) adsorption capacities at 840+/-20 and 720+/-10 mg/g bio-sludge, respectively. The adsorbed Pb(2+) and Ni(2+) were easily eluted (70-77%) from bio-sludge by washing with 0.1 mol/l HNO(3) solution. The heavy metals (Pb(2+), Ni(2+)) removal efficiency of both SBR and GAC-SBR systems were increased with the increase of hydraulic retention time (HRT), or the decrease of organic loading. The SBR system showed higher heavy metals removal efficiency than GAC-SBR system at the same organic loading or HRT. The Pb(2+), Ni(2+), BOD(5), COD and TKN removal efficiencies of GAC-SBR system were 88.6+/-0.9%, 94.6+/-0.1%, 91.3+/-1.0%, 81.9+/-1.0% and 62.9+/-0.5%, respectively with industrial estate wastewater (IEWW) with 410 mg/l glucose, 5 mg/l Pb(2+) and 5 mg/l Ni(2+) under organic loading of 1.25 kg BOD(5)/m(3) d (HRT of 3 days). The bio-sludge quality (sludge volume index: SVI) of the system was less than 80 ml/g. The excess sludge from both SBR and GAC-SBR systems with SIEWW under the organic loading of 1.25-2.50 kg BOD(5)/m(3) d contained Pb(2+) and Ni(2+) at concentrations of 240-250 mg Pb(2+)/g bio-sludge and 180-210 mg Ni(2+)/g bio-sludge, respectively.     

Decolorization of Molasses Waste Water by a Thermophilic Strain,Aspergillus fumigatus G-2-6 Sadahiro

We screened for fungi that can decolorize molasses melanoidin in the tropical zone and isolated some strains, mainly in the genus Aspergillus. Of these, strain No. G-2–6 was most active and was identical with Aspergillus fumigatus based on detailed morphological studies.

This strain decolorized about 75% of a molasses melanoidin solution when the strain was cultivated on a glycerol-peptone medium at 45°C for 3 days with shaking. In successive decolorization reusing the mycelia, this strain had more than 60% of the melanoidin-decolorizing activity at the eighth replacement in the presence of 4% glycerol.

Continuous decolorization of molasses melanoidin solution in a jar fermentor had an almost constant decolorization yield of about 70% at a dilution rate of 0.014 hr^-1. At the same time, about 51 % of the chemical oxygen demand and 56% of the total organic carbon in the initial solution were removed. In contrast, continuous decolorization of non-dialyzed molasses melanoidin solution removed a little more chemical oxygen demand and total organic carbon than those of dialyzed molasses melanoidin solution, but had a lower level of melanoidin-decolorizing activity (about 40%).     

Some properties of a sequencing batch reactor system for removal of vat dyes

Bio-sludge from a wastewater treatment plant could be used as an adsorbent of vat dye from textile wastewater. Resting bio-sludge gave a higher adsorption capacity than dead bio-sludge. The resting bio-sludge from a textile wastewater treatment plant gave relatively high COD, BOD5 and dye adsorption capacity of 364.4 +/- 4.3, 178.0 +/- 9.0 and 50.5 +/- 1.3 mg/g of bio-sludge, respectively, in synthetic textile wastewater containing 40 mg/l Vat Yellow 1. Another advantage of the bio-sludge was that, after washing with 0.1 N NaOH solution, it was reusable without any activity loss. Through treatment with a sequencing batch reactor (SBR) system, both organic and dye in STIWW could be removed. The maximum dye (Vat Yellow 1), COD, BOD5 and TKN removal efficiencies of the SBR system under an MLSS of 2000 mg/l and an HRT of three days were 98.5 +/- 1.0%, 96.9 +/- 0.7%, 98.6 +/- 0.1% and 93.4 +/- 1.3%, respectively. Although, the dye and organic removal efficiencies of the SBR system with real textile wastewater were quite low, they could be increased by adding organic matters, especially glucose. The dye, COD, BOD5 and TKN removal efficiencies of the SBR system with glucose (0.89 g/l) supplemented textile industrial wastewater were 75.12 +/- 1.2%, 70.61 +/- 3.4%, 96.7 +/- 0.0%, and 63.2 +/- 1.1%, respectively.