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1.
The requirements for treated wastewater are becoming increasingly more stringent, and therefore the improved efficiency of biological treatment processes is indispensable at industrial effluent treatment plants (ETPs). Microorganisms such as bacteria play an important role in the natural cycling of materials and particularly in the decomposition of organic wastes. The knowledge of the interactions among these microbial populations needs to be harnessed for optimum evaluation and functioning of effluent treatment plants. Modern molecular techniques have revolutionized the methods of assessing these microbial populations. The combination of the results of these microbial assessments along with the on-site parameters at ETPs would favor an efficient treatment. In this review, the various approaches and importance of correlating the microbial population dynamics and treatment of wastewater at industrial ETPs has been elaborated. 相似文献
2.
Chauhan Hemant Pandey Ashutosh Mishra Saurabh Rai Shashi Kant 《Environment, Development and Sustainability》2021,23(11):16769-16785
Environment, Development and Sustainability - Our society faces mounting pressure regarding the necessity of green consumption as issues related to the environment will likely become a severe... 相似文献
3.
Impact of Bioaugmentation with a Consortium of Bacteria on the Remediation of Wastewater-Containing Hydrocarbons (5 pp) 总被引:1,自引:0,他引:1
Domde P Kapley A Purohit HJ 《Environmental science and pollution research international》2007,14(1):7-11
Goals, Scope and Background It has been observed that hydrocarbon treated wastewaters still contain high COD and a number of intermediates. This suggests
that the required catabolic gene pool for further degradation might be absent in the system or, that its titer value is not
significant enough. By providing the desired catabolic potential, the overall efficiency of the treatment system can be improved.
This study aims to demonstrate this concept by bioaugmentation of a lab-scale reactor treating refinery wastewater with a
consortium having the capacity to complement the alkB genotype to the available microbial population.
Methods Two reactors were set up using activated biomass collected from a refinery treatment plant and operated at a continuous mode
for a period of 8 weeks. The feed to both reactors was kept constant. Crude oil was spiked regularly. One reactor was bioaugmented
with a consortium previously described for crude oil spill remediation. The efficiency of the bioaugmented reactor was demonstrated
by reduced COD. The changes in the microbial population over a period of time were analyzed by RAPD. Catabolic activity of
the biomass in both reactors was monitored by PCR. The presence of the catabolic loci was confirmed by Southern Hybridization.
Results and Discussion 52.2% removal of COD was observed in the bioaugmented reactor while only 15.1% reduction of COD was observed in the reactor
without bioaugmentation. The change in microbial population can be seen from the 4th week, which also corresponds to improved
catabolic activity. The presence of the bedA locus was seen in all samples, which indicates the presence of aromatic degraders,
but the appearance of the alkB locus, from the 6th week onwards, which was observed only in the samples from the bioaugmented
reactor. The results suggest that the gene pool of the bioaugmented reactor has catabolic loci that can degrade accumulated
intermediates, thus improving the efficiency of the system.
Conclusions In this study, improvement of efficiency of bioremediation was demonstrated by addition of catabolic loci that are responsible
for degradation. Bioaugmentation was carried out in biomass that was collected from an ETP (effluent treatment plant) treating
hydrocarbon containing wastewater to study the strategies for improvement of the treatment system. Biostimulation, only marginally
improved the efficiency, when compared to bioaugmentation. The improved efficiency was demonstrated by COD removal. The presence
of the alkB locus suggests the importance of a catabolic gene pool that acts on accumulated intermediates. It is well documented
that straight chain aliphatics and intermediates of aromatic compounds after ring cleavage, accumulate in refinery wastewater
systems, thereby hindering further degradation of the wastewater. Supplementation of a catabolic gene pool that treats the
lower pathway compounds and alkanes will improve the overall efficiency. In this study, results suggest that the alkB locus
can also be used to monitor the degradative mode of the activated biomass.
Recommendations and Perspective . Pollution from petroleum and petroleum products around the globe are known to have grave consequences on the environment.
Bioremediation, using activated sludge, is one option for the treatment of such wastes. Effluent treatment plants are usually
unable to completely degrade the wastewater being treated in the biological unit (the aerator chambers). The efficiency of
degradation can be improved by biostimulation and bioaugmentation. This study demonstrates the improved efficiency of a treatment
system for wastewater containing hydrocarbons by bioaugmentation of a consortium that supports degradation. Further experiments
on a pilot scale are recommended to assess the use of bioaugmentation on a large scale. The use of molecular tools, like DNA
probes for alkB, to monitor the system also needs to be explored. 相似文献
4.
Low dissolved oxygen (DO) concentrations occur commonly in aerobic digesters treating thickened sludge, with benefits of smaller digester size, much reduced aeration cost, and higher digestion temperature (especially important for plants in colder areas). The effects of low DO concentrations on digestion kinetics were studied using the sludge from municipal wastewater treatment plants in Akron, Ohio, and Los Lunas, New Mexico. The experiments were conducted in both batch digestion and a mixed mode of continuous, fed-batch, and batch operations. The low DO condition was clearly advantageous in eliminating the need for pH control because of the simultaneous occurrence of nitrification and denitrification. However, when compared with fully aerobic (high DO) systems under constant pH control (rare in full-scale plants), low DO concentrations and a higher solids loading had a negative effect on the specific volatile solids (VS) digestion kinetics. Nonetheless, the overall (volumetric) digestion performance depends not only on the specific digestion kinetics, but also the solids concentration, pH, and digester temperature. All of the latter factors favor the low DO digestion of thickened sludge. The significant effect of temperature on low DO digestion was confirmed in the mixed-mode study with the Akron sludge. When compared with the well-known empirical correlation between VS reduction and the product (temperature x solids retention time), the experimental data followed the same trend, but were lower than the correlation predictions. The latter was attributed to the lower digestible VS in the Akron sludge, the slower digestion at low DO concentrations, or both. Through model simulation, the first-order decay constant (kd) was estimated as 0.004 h(-1) in the mixed-mode operations, much lower than those (0.011 to 0.029 h(-1)) obtained in batch digestion. The findings suggested that the interactions among sludges with different treatment ages may have a substantially negative effect on digestion kinetics. The use of multistage digesters, especially with small front-end reactors, may be advantageous in both "process" kinetics and "biological reaction" kinetics for sludge digestion. 相似文献
5.
Anshuman A. Khardenavis Atya Kapley Hemant J. Purohit 《Waste management (New York, N.Y.)》2009,29(4):1409-1415
The present study describes the production and characterization of a feather hydrolyzing enzyme by Serratia sp. HPC 1383 isolated from tannery sludge, which was identified by the ability to form clear zones around colonies on milk agar plates. The proteolytic activity was expressed in terms of the micromoles of tyrosine released from substrate casein per ml per min (U/mL min). Induction of the inoculum with protein was essential to stimulate higher activity of the enzyme, with 0.03% feathermeal in the inoculum resulting in increased enzyme activity (45 U/mL) that further increased to 90 U/mL when 3 d old inoculum was used. The highest enzyme activity, 130 U/mL, was observed in the presence of 0.2% yeast extract. The optimum assay temperature and pH for the enzyme were found to be 60 °C and 10.0, respectively. The enzyme had a half-life of 10 min at 60 °C, which improved slightly to 18 min in presence of 1 mM Ca2+. Inhibition of the enzyme by phenylmethyl sulfonyl fluoride (PMSF) indicated that the enzyme was a serine protease. The enzyme was also partially inhibited (39%) by the reducing agent β-mercaptoethanol and by divalent metal ions such as Zn2+ (41% inhibition). However, Ca2+ and Fe2+ resulted in increases in enzyme activity of 15% and 26%, respectively. The kinetic constants of the keratinase were found to be 3.84 μM (Km) and 108.7 μM/mL min (Vmax). These results suggest that this extracellular keratinase may be a useful alternative and eco-friendly route for handling the abundant amount of waste feathers or for applications in other industrial processes. 相似文献
6.
The photocatalysed degradation of two selected priority organic pollutants, namely benzidine (1) and 1,2-diphenylhydrazine (DPH, 2) has been investigated in aqueous suspensions of titanium dioxide (TiO2) under a variety of conditions employing a pH-stat technique. The degradation was studied by monitoring the change in substrate concentration of the model compound employing HPLC analysis and the decrease in total organic carbon content, respectively, as a function of irradiation time. The degradation kinetics were studied under different conditions such as reaction pH, substrate and photocatalyst concentration, type of TiO2 photocatalyst and the presence of alternative additives such as H2O2, KBrO3 and (NH4)2S2O8 besides molecular oxygen. The degradation rates and the photonic efficiencies were found to be strongly influenced by the above parameters. Toxicity tests for the irradiated samples of benzidine measuring the luminescence of bacteria Vibrio fischeri after 30 min of incubation were also performed. 4-amino-biphenyl (7) and hydroquinone (13) were identified as intermediate products by GC/MS technique and probable pathways for the formation of the products are proposed. 相似文献
7.
Maitreya Anuja Pal Smita Qureshi Asifa Reyed Reyed M. Purohit Hemant J. 《Environmental science and pollution research international》2022,29(4):4911-4929
Environmental Science and Pollution Research - Membrane biofouling in water purification plants is a serious issue of worldwide concern. Various chemical, physical, and biochemical processes are... 相似文献
8.
Anubhav Kaphle P. N. Navya Akhela Umapathi Hemant Kumar Daima 《Environmental Chemistry Letters》2018,16(1):43-58
Nanotechnology is expected to have a beneficial influence on agriculture, food and environment, due to the unique properties of nanomaterials. However, little is known about their safety and potential toxicity. Here we review metal nanoparticles, nanometal oxides, carbon nanotubes, liposomes and dendrimers. We present the application of these nanomaterials in agriculture, food and environment for plant protection; disease treatment; packing materials; development of new tastes, textures and sensations; pathogen detection; and delivery systems. We discuss risk assessment of nanomaterials and toxicological impacts of nanomaterials on agriculture, food and environment. We then provide regulatory guidelines for the safer use of nanomaterials. 相似文献
9.
Nishant Dafale Shrikumar Lakhe Krishnakant Yadav Hemant Purohit Tapan Chakrabarti 《Water environment research》2008,80(3):282-288
Coliphages represent a process indicator for fecal pollution. The coal bed concentration method prepared for enterovirus was refined for a concentration of coliphages. A bed made from 1.5 g of 120-mesh coal powder was used for concentrating coliphage from 200 mL of a water sample with or without the addition of aluminum chloride at different pH values. The isolated E. coli strain EC-R8 was found to be more susceptible to the desired coliphage and showed significant coliphage-coliform response, with clear plaque used for further studies. The complete coliphage adsorption was achieved with the addition of 0.0005 M AlCl3 at pH 6.0. Adsorbed coliphages were eluted with 3% beef extract in Mcllvaine buffer at pH 7.1, with an average recovery of 78.74%. This concentration technique was applied for the detection of coliphages from the well water of Nagpur city (India) and found to contain coliphages in the range of 2 to 28 plaque-forming units per liter (PFU/L). 相似文献
10.
Environmental Fluid Mechanics - Pedestrian level wind comfort, natural ventilation and pollutant dispersion are strongly influenced by building shape and orientation. In the recent years, the trend... 相似文献