Phytoremediation of wastewater toxicity using water hyacinth (Eichhornia crassipes) and water lettuce (Pistia stratiotes)

This paper elucidates the phytoremediation potential of water hyacinth and water lettuce on the reduction of wastewater toxicity. Acute toxicity tests were performed in an aquarium with a population of Sarotherodon melanotheron, contaminated by different concentrations of wastewaters before and after phytoremediation with Eichhornia crassipes and Pistia stratiotes. Lethal concentrations (LC₅₀) of the fish's population obtained during 24 hours of exposures were determined. COD, BOD, ammonium, TKN and PO₄^3? concentrations in wastewaters were of 1850.29, 973.33, 38.34, 61.49 and 39.23 mg L^?1, respectively, for each plant. Phytoremediation reduced 58.87% of ammonium content, 50.04% of PO₄^3?, 82.45% of COD and 84.91% of BOD. After 15 days of the experiment, metal contents in treated wastewaters decreased from 6.65 to 97.56% for water hyacinth and 3.51 to 93.51% for water lettuce tanks. Toxicity tests showed that the mortality of fish exposed increased with increase in concentration of pollutants in wastewaters and the time of exposure. Therefore, the highest value of LC₅₀ was recorded for fish subjected to 3 hours of exposure (16.37%). The lowest rate was obtained after an exposure of 20 to 24 hours (5.85%). After phytoremediation, the effluents purified by Eichhornia crassipes can maintain the fish life beyond 24 hours of exposure.     

Biodegradation of coal slurry transport wastewater organics

Summary Activated sludge was successful in reducing the levels of dissolved organic carbon (DOC) in coal slurry wastewaters. DOC removal by the activated sludge ranged from 61% to 97% with a large percentage (21–41%) of this DOC being completely metabolized to CO₂. Second order kinetic constants (k ₂) developed for DOC removal ranged from 1.39·10^–4 to 2.30·10^–1 liter·day^–1·(mg of sludge)^–1, providing evidence that biological treatment was an effective mechanism for reducing the pollution potential of the slurry wastewaters. After treatment with activated sludge a residual DOC remained in the wastewater and data from ultrafiltration studies indicated that this residual carbon was of MW>1000. The activated sludge preferentially removed the lower (MW<1000) molecular weight compounds and the higher molecular weight DOC was more resistant to biological attack. However, extended acclimation (greater than 1 month) enabled the activated sludge to remove the higher molecular weight DOC from the slurry wastewaters.     

Bacterial and β-proteobacterial diversity in Olea europaea var. mastoidis- and O. europaea var. koroneiki-generated olive mill wastewaters: influence of cultivation and harvesting practice on bacterial community structure

Despite the fact that several approaches have been applied for the bioremediation of olive mill wastewaters, little information is available on bacteria inhabiting these agro-industrial effluents. In the present study, 16S rRNA gene clone libraries were constructed to identify bacterial diversity in olive-oil mill wastewaters generated by two olive varieties, Olea europaea var. mastoidis and O. europaea var. koroneiki. Due to chloroplast excess in wastewater produced from the processing of O. europaea var. koroneiki, a clone library using specific PCR primers for β-Proteobacteria was further constructed. The bacterial diversity in O. europaea var. mastoidis-generated olive mill wastewaters consisted mainly of members of Acetobacteriaceae, Prevotellaceae and Lactobacillaceae, while the majority of β-proteobacteria identified in O. europaea var. koroneiki-generated olive mill wastewaters were placed within the families Comamonadaceae, Oxalobacteraceae, Hydrogenophilaceae and Rhodocyclaceae. At least 17 novel phylogenetic linkages among Bacteria were identified. Olive-oil mill wastewaters microbiota appears to have originated from soil and freshwater environments, while the cultivation and harvesting practice highly influenced the bacterial community structure in olive mill wastewaters. The presence of fecal bacteria in O. europaea var. mastoidis-generated olive mill wastewaters, due to the long harvesting period, should be of concern.     

Tolerance and phytoaccumulation of Chromium by three Azolla species

Azolla, an aquatic fern is ideal candidate for exploitation in constructed wetlands for treating metal-contaminated wastewaters. This study demonstrates the potential of Azolla spp. namely A. microphylla, A. pinnata and A.␣filiculoides to tolerate Cr ions in the growth environment and bioconcentrate them. These species could grow in presence of up to 10 μg ml⁻¹ Cr and showed biomass production 30–70% as compared to controls. Nitrogenase activity was not affected at 1–5 μg ml⁻¹ but at higher concentrations it diminished. There was no growth at higher concentrations of chromium. However, the necrosed biomass harvested from treatments containing higher concentrations of chromium, accumulated Cr to the levels 5000–15,000 μg g⁻¹. At increased levels of Cr, the metal was accumulated in higher amount in dry biomass. Bioconcentration Factor (BCF) ranged between 243 and 4617 for the three species. A. microphylla showed highest bioconcentration potential. Thus, these Azolla spp. can be exploited for treatment of tannery and other Cr contaminated wastewaters.     

Comparative anaerobic treatment of wastewater from pharmaceutical,brewery, paper and amino acid producing industries

This study concerned the anaerobic treatment of five different industrial wastewaters with a diverse and complex chemical composition. The kinetics of biotransformation of this wastewater at different chemical oxygen demand (COD) were studied in a batch reactor. Wastewater from an amino acid producing industry (Fermex) and from a tank that received several types of wastewaters (collector) contained 0.83 g l⁻¹ and 0.085 g l⁻¹ sulfate, respectively. During the study period of 20 days, methane formation was observed in all types of wastewaters. Studies on COD biodegradation showed the reaction velocity was higher for Fermex wastewater and lower for collector wastewater, with values of 0.0022 h⁻¹ and 0.0011 h⁻¹, respectively. A lower methanogenic activity of 0.163 g CH₄ day⁻¹ g⁻¹ volatile suspended solids (VSS) and 0.20 g CH₄ day⁻¹ g⁻¹ VSS, respectively, was observed for paper producing and brewery wastewater. Adapted granular sludge showed the best biodegradation of COD during the 20-day period. The sulfate-reducing activity in pharmaceutical and collector wastewater was studied. A positive effect of sulfate-reducing activity on methanogenic activity was noted for both types of wastewaters, both of which contained sulfate ions. All reactions of methane generation for the tested industrial wastewaters were first-order. The results of this study suggest that the tested wastewaters are amenable to anaerobic treatment.

     

Identification of Efficient Denitrifying Bacteria from Tannery Wastewaters in Ethiopia and a Study of the Effects of Chromium III and Sulphide on Their Denitrification Rate

In order to identify potential microorganisms with high denitrifying capacity from tannery wastewaters, 1000 pure cultures of bacterial isolates from Modjo Tannery Pilot and Ethio-tannery wastewater treatment plants (WWTP), in Ethiopia, were investigated. Twenty-eight isolates were selected as efficient denitrifiers. These were Gram-negative rods, oxidase and catalase positive denitrifying organisms. The 28 denitrifying strains were further classified according to their biochemical fingerprints into three different phylogenetic groups (BPT1, BPT2 and BPT3) and seven singles. Isolates B79^T, B11, B12, B15, B28 and B38 belonging to the BPT3 cluster were found to be the most efficient denitrifying bacteria. All phenotypic studies, including cellular fatty acid profiles, showed that the 6 BPT3 isolates were closely related to each other. The 16S rRNA partial sequence analysis of type strain B79^T(CCUG 45880) indicated a sequence similarity of 99% to Brachymonas denitrificans JCM9216 (D14320) in the β-subdivision of proteobacteria. Further studies of the effects of chromium III and sulphide on the six Brachymonas denitrificans strains indicated that denitrification by the isolates were inhibited 50% at concentrations of 54 and 96 mg/l, respectively. The efficient isolates characterized in this study are of great value because of their excellent denitrifying properties and relatively high tolerance to the concentrations of toxic compounds (70 mg chromium/l and 160 mg sulphide/l) prevailing in tannery wastewaters.     

Potential for bioremediation of agro-industrial effluents with high loads of pesticides by selected fungi

Wastewaters from the fruit packaging industry contain a high pesticide load and require treatment before their environmental discharge. We provide first evidence for the potential bioremediation of these wastewaters. Three white rot fungi (WRF) (Phanerochaete chrysosporium, Trametes versicolor, Pleurotus ostreatus) and an Aspergillus niger strain were tested in straw extract medium (StEM) and soil extract medium (SEM) for degrading the pesticides thiabendazole (TBZ), imazalil (IMZ), thiophanate methyl (TM), ortho-phenylphenol (OPP), diphenylamine (DPA) and chlorpyrifos (CHL). Peroxidase (LiP, MnP) and laccase (Lac) activity was also determined to investigate their involvement in pesticide degradation. T. versicolor and P. ostreatus were the most efficient degraders and degraded all pesticides (10 mg l⁻¹) except TBZ, with maximum efficiency in StEM. The phenolic pesticides OPP and DPA were rapidly degraded by these two fungi with a concurrent increase in MnP and Lac activity. In contrast, these enzymes were not associated with the degradation of CHL, IMZ and TM implying the involvement of other enzymes. T. versicolor degraded spillage-level pesticide concentrations (50 mg l⁻¹) either fully (DPA, OPP) or partially (TBZ, IMZ). The fungus was also able to rapidly degrade a mixture of TM/DPA (50 mg l⁻¹), whereas it failed to degrade IMZ and TBZ when supplied in a mixture with OPP. Overall, T. versicolor and P. ostreatus showed great potential for the bioremediation of wastewaters from the fruit packaging industry. However, degradation of TBZ should be also achieved before further scaling up.     

Functional consortium for denitrifying sulfide removal process

Denitrifying sulfide removal (DSR) process simultaneously converts sulfide, nitrate, and chemical oxygen demand from industrial wastewaters to elemental sulfur, nitrogen gas, and carbon dioxide, respectively. This investigation utilizes a dilution-to-extinction approach at 10⁻² to 10⁻⁶ dilutions to elucidate the correlation between the composition of the microbial community and the DSR performance. In the original suspension and in 10⁻² dilution, the strains Stenotrophomonas sp., Thauera sp., and Azoarcus sp. are the heterotrophic denitrifiers and the strains Paracoccus sp. and Pseudomonas sp. are the sulfide-oxidizing denitrifers. The 10⁻⁴ dilution is identified as the functional consortium for the present DSR system, which comprises two functional strains, Stenotrophomonas sp. strain Paracoccus sp. At 10⁻⁶ dilution, all DSR performance was lost. The functions of the constituent cells in the DSR granules were discussed based on data obtained using the dilution-to-extinction approach.     

Production of elemental sulfur from sulfide and nitrate-laden wastewaters by methanogenic culture via sulfide denitrifying removal process

The denitrifying sulfide removal (DSR) process is a biorefinery process that can produce colloidal S⁰ from sulfide and nitrate-laden wastewaters. At long reaction time the formed S⁰ produced is reduced back to sulfide by sulfate-reducing bacteria so the resulting in poor conversion rate of S⁰ is poor. The presence of optimal hydraulic retention time (HRT) for maximizing S⁰ conversion from DSR wastewaters was proposed by batch assays and then confirmed in continuous flow tests.     

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%.     

Azotobacter vinelandii biomass production from olive-mill wastewaters for heavy metal recovery

Sixteen litres of olive-mill wastewaters (OMW) diluted to 5% organic matter (d.w.) were inoculated in a fermentor (T=30°C, air FLOW=161min⁻¹, STIRRING=100 rpm) with a strain of Azotobacter vinelandii. After 2 weeks the bacterial biomass was separated by centrifugation and capsular polysaccharide (CPS) and exopolysaccharides were extracted. The apparent molecular weight of CPS was determined by gel filtration. The CPS was entrapped in polyvinyl alcohol membranes which were used to adsorb cadmium and lead ions from a liquid stream.     

Comparison of the Adsorption Capabilities of Myriophyllum spicatum and Ceratophyllum demersum for Zinc,Copper and Lead

Industrial wastewaters contain various heavy metal components and therefore threaten aquatic bodies. Heavy metals can be adsorbed by living or non‐living biomass. Submerged aquatic plants can be used for the removal of heavy metals. This paper exhibits the comparison of the adsorption properties of two aquatic plants Myriophyllum spicatum and Ceratophyllum demersum for lead, zinc, and copper. The data obtained from batch studies conformed well to the Langmuir Model. Maximum adsorption capacities (q_max) were obtained for both plant species and each metal. The maximum adsorption capacities (q_max) achieved with M. spicatum were 10.37 mg/g for Cu²⁺, and 15.59 mg/g for Zn²⁺ as well as 46.49 mg/g for Pb²⁺ and with C. demersum they were 6.17 mg/g for Cu²⁺, 13.98 mg/g for Zn²⁺ and 44.8 mg/g for Pb²⁺. It was found that M. spicatum has a better adsorption capacity than C. demersum for each metal tested. Gibbs free energy and the specific surface area based on the q_max values were also determined for each metal.     

New method for toxicity assessment in marine and brackish environments using the macroalga Gracilaria tenuistipitata (Gracilariales,Rhodophyta)

A growth inhibition test method was developed using the macroalga Gracilaria tenuistipitata as the test organism. This alga was chosen because of its high laboratory growth rates, commonly 30–40% d^–1, which are reached in salinities between 5 and 40, and its epiphyte resistance. The toxicity of a number of substances, including heavy metals, herbicides and complex wastewaters towards the alga was assayed. Anti-fouling paints were tested with a modification of the method. EC50 values for heavy metals varied between 0.05 and 17 mg l^–1 and for herbicides between 0.002 and 0.02 mg l^–l. The sensitivity to the toxicant was generally higher at low salinity. Omitting nitrogen and phosphorus additions to the test medium increased the sensitivity and a semi-static performance was possible with maintained or increased sensitivity. Preliminary tests done with a computerised photosynthesis inhibition method produced promising results.In conclusion, this is a simple, sensitive and reproducible test method for assessing the toxicity of substances, wastewaters and anti-fouling paints in brackish and marine environments.     

Chromium and aluminum biosorption on<Emphasis Type="Italic"> Chryseomonas luteola</Emphasis> TEM05

Cr(VI) and Al(III) are environmental pollutants that are frequently encountered together in industrial wastewaters, e.g., from mining iron-steel, metal cleaning, plating, metal processing, automobile parts, and the manufacturing and dye industries. In this work, several variables that affect the capacity for chromium and aluminum biosorption by Chryseomonas luteola TEM05 were studied, particularly the effects of pH, metal concentration and contact time. Optimum adsorption pH values of Cr(VI) and Al(III) were determined as 4.0 and 5.0, respectively. The biosorption equilibrium was described by Freundlich and Langmuir adsorption isotherms. The value of Q ^o appears to be significantly higher for the Al(III) C. luteola TEM05 system. Langmuir parameters of C. luteola TEM05 also indicated a maximum adsorption capacity of 55.2 mg g^–1 for Al(III) and 3.0 mg g^–1 for Cr(VI).     

Influence of sulfates and operational parameters on volatile fatty acids concentration profile in acidogenic phase

Anaerobic treatment of distillery wastewaters containing high sulfate concentrations was carried out on a two-phase process. The acidogenic phase was operated so as to produce the more favourable intermediates for methanogenic bacteria coupled with maximum sulfate removal. Sulfate removal was directly affected by pH and dilution rate (D). The maximum sulfate removal and acetic acid production was achieved at pH 6.6 and D=0.035 h^–1. A linear relationship between acetic acid produced and sulfate removal was observed, indicating that acetic acid was mainly produced by sulfate reducing bacteria with important operational advantages. Higher concentrations of butyric acid were obtained at low pH values and high dilution rates.     

Thermophilic H2 production from a cellulose-containing wastewater

Cellulose in wastewater was converted into H₂ by a mixed culture in batch experiments at 55°C with various wastewaters pH (5.5–8.5) and cellulose concentrations (10–40 g l^–1). At the optimal pH of 6.5, the maximum H₂ yield was 102 ml g^–1 cellulose and the maximum production rate was 287 ml d^–1 for each gram of volatile suspended solids (VSS). Analysis of 16S rDNA sequences showed that the cellulose-degrading mixed culture was composed of microbes closely affiliated to genus Thermoanaerobacterium.     

Removal of inorganic ions from wastewaters by immobilized microalgae

Anabaena doliolum and Chlorella vulgaris immobilized on chitosan were more efficient at removing NO₃ ^–, NO₂ ^p–, PO₄ ^3– and CR₂O₇ ^2– from wastewaters than cells immobilized on agar, alginate, carrageenan or even free cells. Carrageenan-immobilized cells, however, were better at removing NH₄ ⁺ and Ni²⁺. The PO₄ ^3– uptake capacity was significantly increased in cells starved of PO₄ ^3– for 24 h. Agar-immobilized cells, though having good metal and nutrient uptake efficiency, had only a slow growth rate. Chitosan is recommended as an algal support for wastewater detoxification.The authors are with the Laboratory of Algal Biology, Department of Botany, Banaras Hindu University, Varanasi-221005, India     

Production of tannase by <Emphasis Type="Italic">Aspergillus niger</Emphasis> HA37 growing on tannic acid and Olive Mill Waste Waters

Production of tannase (tannin acyl hydrolase, EC 3.1.1.20) by Aspergillus nigerHA37 on a synthetic culture medium containing tannic acid at different concentrations has been studied. Maximal enzymatic activity increased according to the initial concentration of tannic acid; respectively 0.6, 0.9 and 1.5 enzyme activity units (EU) ml⁻¹ medium in the presence of 0.2%, 0.5% and 1% of tannic acid. Tannase production by A. niger HA37 on fourfold diluted olive mill waste waters (OMWW) as substrate, was between 0.37 and 0.65 EU ml⁻¹. Enzyme production on the diluted OMWW remained globally stable during more than 30 h. Growth of A. niger HA37 on OMWW was correlated with about 70% degradation of phenolic compounds present in the waste. This strain has therefore the capacity to degrade complex wastewaters which cause environmental damage to aquatic streams.     

Quantification of Bacterial Indicators and Zoonotic Pathogens in Dairy Wastewater Ponds

Zoonotic pathogens in land-applied dairy wastewaters are a potential health risk. The occurrence and abundance of 10 pathogens and 3 fecal indicators were determined by quantitative real-time PCR (qPCR) in samples from 30 dairy wastewaters from southern Idaho. Samples tested positive for Campylobacter jejuni, stx₁- and eaeA-positive Escherichia coli, Listeria monocytogenes, Mycobacterium avium subsp. paratuberculosis, and Salmonella enterica, with mean recoveries of genomic DNA corresponding to 10² to 10⁴ cells ml⁻¹ wastewater. The most predominant organisms were C. jejuni and M. avium, being detected in samples from up to 21 and 29 of 30 wastewater ponds, respectively. The qPCR detection limits for the putative pathogens in the wastewaters ranged from 16 cells ml⁻¹ for M. avium to 1,689 oocysts ml⁻¹ for Cryptosporidium. Cryptosporidium and Giardia spp., Yersinia pseudotuberculosis, and pathogenic Leptospira spp. were not detected by qPCR.     

Nitrosomonas sp. Based biosensor for ammonium nitrogen measurement in wastewater

A bacterial culture of Nitrosomonas sp. was isolated from a nitrifying biofilm to construct a biosensor for ammonium nitrogen (NH ₄ ⁺ ?N) measurements in high ammonia wastewaters. The pure culture of microorganisms was immobilized into agarose gel matrix to attain a stable biosensor with a long service life. Biosensors were calibrated using (NH₄)₂SO₄ solution and a steady-state method. Subsequently, several experiments with synthetic and industrial wastewaters were conducted. A linear range up to 20 mg/L of NH ₄ ⁺ ?N, and sensitivities between 0.030 and 0.036 were gained with biosensors. During 14 days of stable service life of the Nitrosomonas sp. biosensors, variation of the signal was less than 7%. Response times of biosensors were 15 ～ 25 min, while recovery times were up to 25 min. Measurements with high ammonia content synthetic and industrial wastewaters were conducted, and 8.3 and 5.6% over estimation of NH ₄ ⁺ ?N was gained, respectively, compared with results of Nessler method. In spite of the small overestimation, the biosensor based on a pure culture of Nitrosomonas sp. and calibrated with (NH₄)₂SO₄ is suitable for the analysis of NH ₄ ⁺ ?N in high ammonia content wastewaters.