BIOREMEDIATION OF POLLUTED KAMLA RIVER WATER BY PHYSICAL, BIOLOGICAL AND ECOLOGICAL PROCESSES

The increasing need for remediation of contaminated sites has led to the development of new technologies that emphasize on the biological detoxification anddestructionofthe(organic)contaminants.Bioremediationisamongthesetechnologiesthatdestroyorrenderharmlessvariouscontaminants,usingthebiologicalactivityofcertainmicroorganisms[1].Needlesstosaythatasbioremediationactuallyreliesonthemicrobialgrowthandactivity,itseffectivenessishighlydependentontheappliedenvironmentalparametersthatinfluencethemicrobialgrowthandthedegradationrate.Bioremediationtechnologiescanbeclassifiedintotwogeneralcategories:exsituandinsitu.Theexsitutechniquesarethosethatrequirethe physical removal of the contaminated material and its transportation to another area for further treatment, for example, by bioreactors, landfarming and composting. The insitute chnologies are those that involve treatment of contaminated material in place, for example, by bioventing, biostimulation and biopiling. Overall, bioremediation isconsideredasaverypromisingtechnologywithgreatpotentialwhendealingwithcertaintypesofcontaminatedsites.Sofar,ithasbeenusedatanincreasingnumberofsitesworldwide,includingEurope,withvaryingsuccess.Theapplicationofbioremediationandphytoremediationofferssignificantbenefitstoenvironmentalpollutionabatementand,moreimportantly,tohumanhealthhowever,theriskofadversehealtheffectsmaybepresentduetothevariabilityofcontaminantsandtheirpossiblebiotransformationtowardnotcontrolledmetabolites.Therefore,specificcontrolproceduresshouldalsotakeplace.

The increasing need for remediation of contaminated sites has led to the development of new technologies that emphasize on the biological detoxification anddestructionofthe(organic)contaminants.Bioremediationisamongthes etechnologiesthatdestroyorrenderharmlessvariouscontaminants,usingthe biologicalactivityofcertainmicroorganisms [1].Needlesstosaythatasbiore mediationactuallyreliesonthemicrobialgrowthandactivity,itseffectivenes sishighlydependentontheappliedenvironmentalparametersthatinfluencet hemicrobialgrowthandthedegradationrate.Bioremediationtechnologiesc anbeclassifiedintotwogeneralcategories:exsituandinsitu.Theexsitutechni quesarethosethatrequirethe physical removal of the contaminated material and its transportation to another area for further treatment, for example, by bioreactors, landfarming and composting. The insitute chnologies are those that involve treatment of contaminated material in place, for example, by bioventing, biostimulation and biopiling. Overall

Water transfer or Diversion and Dilution
Mixing of clean water with polluted river water and dilution of Pollution [10]. Water transfer provides multiple benefits, such as irrigation, water supply, navigation, flood control, power generation, reducing water crisis, increasing water security, reducing the concentration of nutrients and phytoplankton and improving water quality [10,14]. This method demonstrated the explicit evidence of reduction in the concentrations of NH 4 , other N 2 containing compounds and COD in Kamla river water.

Mechanical Algae Removal
Removal of algae by mechanical process. It minimizes dissolved inorganic Carbon, pH and DO level of Kamla river water [7].

Building Hydraulic Structures
The construction of hydraulic structures such as irrigation weirs or irrigation infrastructure reduces water flow velocity but increases hydraulic retention time, which facilitate sedimentation, aeration, sunlight irradiation and anaerobic reactions, resulting in improving water quality of river [6,8].

Dredging River Sediment
Removal of polluted sediment those sattled down at bottom are picked out by dredgingmachine. This process is also help in creating waterways, removing trash and debris, reopening channels, reconfiguring waterways, restoring banklines, increasing waterways depth, maintaining ecosystem and more of Kamla river.

Riverbank filtration
Riverbank filtration processes remove organic and inorganic contaminants (COD, NH 4 and NO 3 ) from river water, particularly when water flows through the river-bed and groundwater aquifer to the pumping wells [9,10,12].

Biological & Ecological Techniques Microbial Bioremediation
The treatment of polluted Kamla river water by application of microbial agents/photosynthetic bacteria and microalgae-bacteria media significantly degrades organic matter and removes COD and BOD (about 70%) and 34 nutrients.

Biofilm Reactors
The treatment system exhibited very high efficiency to remove Ammonia Nitrogen, BOD, TDS and COD from Kamla river water by using biomembrane [15].

Ecological floating bed
Ecological floating beds use ecological processes and the removal mechanisms involve phytoremediation (heavy metal uptake by plants), microbial biodegradation of organic chemicals and removal of N and P by absorption and sedimentation processes [3,5].

Phytoremediation Process
The most widely used aquatic plants for wastewater treatment are reed (Phragmites australis), water hyacinth (Eichhornia crassipes), alligator weed (Alternanthera philoxeroides), water lettuce (Pistia stratiotes), duckweed (Lemna gibba) and canna (Canna indica). These plants exhibited significant capacity to remove nutrients such as total N and P from water bodies [13].

Constructed Wetlands
Constructed floating bed wetland, horizontal subsurface flow constructed wetland and surface flow constructed wetland are effectively removed COD, NH 4 , TN (total Nitrogen), TP (total Phosphorus) and Suspended Solids from river water [2,9].

Conclusion:-
The random disposal of treated and untreated solid and liquid wastes into water pollutes the receiving river water with nutrients, organic chemicals, metals and nanomaterials [15]. The most widely applied physical processes are aeration, water transfer, mechanical algae removal, building hydraulic structures and dredging river sediment.

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Aeration is an effective, sustainable and widely applicable technique that plays an important role in increasing the diversity of the microbial community and degrading organic chemicals in river water. Riverbank filtration is a natural, slow and self-sustainable process which removes organic and inorganic contaminants from river water without any adverse effects. The microbial agents, ecological floating beds, constructed wetlands and biofilm reactor techniques use microorganisms and plant-based bioremediation processes to decompose organic chemicals and remove nutrients and metals from river water [13,16]. The hybrid, integrated, sequential and engineering-based floating bed wetlands can demonstrate the maximum water purification efficiency and overcome the drawbacks of single constructed floating beds or wetland. However, All the techniques and processes which have been applied on Kamla river water reduce maximum level of inorganic nutrients, organic chemicals, metals and nanomaterials.
Biofilm reactors are highly efficient at remediating polluted river water through the growth of microbial communities in biofilms. The efficiency and stability of the biofilm-based systems are dependent on water flow velocity, hydraulic loading rate, temperature, components of media and water depth. The gravel contact oxidation method is applicable to shallow creeks, but not to deep river water. The moving bed biofilm reactors show high efficiency in the removal of COD and organic matter. The direct mixing of microbial agents with river water moderately removes NH 3 -N, COD and TP, whereas engineering-based applications of microbial agents significantly degrades organic matter and removes COD, BOD and nutrients [1,6,10,12]. However, their application should be monitored cautiously to avoid microbial contamination. Ecological floating bed techniques are more widely applicable for the treatment of river water. Water fluctuation, river waves and inundation do not affect their treatment performances. The appropriate selection of plant species is the key influential parameter for them. Inclusion of high capacity adsorbent materials in the matrix of floating mats enhances their contaminant removal efficiency. The hybrid, integrated, sequential and engineering-based floating bed wetlands can demonstrate the maximum water purification, efficiency and overcome the drawbacks of single constructed floating beds or wetland [2,6,8].