The Valley of Kashmir is known for its serene waters but this does not seem to hold true to a large extent now. Until recently the same water was a free commodity available to all but now due to a large scale pollution of our water bodies the drinking water has become so precious that it is now not only rationed but made available in bottles @ Rs.10 to Rs. 15 a bottle - an irony?
The researches and investigations carried out during the last four decades on water resources of J&K state with particular reference to the valley of Kashmir reveal that the most of our water resources are polluted due to anthropogenic activities and ingress of domestic sewages which find their way to these water resources. The chief chemicals which are hazardous and harmful for the people and to the flora and fauna of the water resources itself are Nitrogen and Phosphorous. Both these chemicals have either increased beyond limits or are increasing steadily so as to render the waters of these resources unfit for drinking purposes. Unfortunately both these chemicals cannot be completely removed through ordinary or by conventional treatments and need tertiary or specialized treatments.
In developed countries like USA, Japan, Canada, Netherlands, Hungary, Costa Rica etc. the frequently available aquatic plants like Typha angustata, Phragmites sp., Acorus calamus,        Sparganium sp.(emergents), Hydrilla verticillata, Ceratophyllum demersum, Potamogeton pectinatus, P.crispus, Utricularia sp., (submerged), Nymphaea stellata, Nymphoides peltatum, Trapa bispinosa (floating leaved), Salvinia natans, Lemna trisulca, Azolla sps. (free- floating) are exploited for wastewater treatments especially for removal of hazardous Nitrates and Phosphates. The expert opinion hold that aquatic plants (macrophytes) provide much of the visible structure of Wastewater Treatment System. The Aquatic plants form an essential component of high quality water treatment performance of most of the Wetland Treatment Systems. The numerous studies measuring treatment with and without plants have concluded almost invariably that performance is higher when plants are present. It is now well established that the plant uptake is the principal removal mechanism only for some pollutants and only in lightly loaded systems. The aquatic plants provide structure for the microbes that mediate most of the pollutant transformation that occur in wetlands or lakes. Understanding the ecological properties of the aquatic plant species is essential for successful wetland treatment system, construction and operation.
Phytoremediation technology using aquatic plants in constructed wetlands and detention ponds is increasingly applied to remediate eutrophic waters (Qin Lu et al., 2010). Phytoremediation has been increasingly used to clean up contaminated soil and water systems because of its lower costs and fewer negative effects than physical or chemical engineering approaches (Gumbricht 1993; Kowalik et al. 1998; Mahujchariyawong and Ikeda 2001). The principles of phytoremediation systems for cleaning up eutrophic water include:
(a) identification and implementation of efficient aquatic plant systems;
(b) uptake of dissolved nutrients including N, P, and metals by the growing plant; and
(c) harvest and beneficial use of the plant biomass produced from the remediation system.

Aquatic plants and adaptation:
The aquatic plants have developed certain adaptations, one such adaptation to flooding is the development of airy tissue or arenchyma plant tissue that treatment gases to and from the roots through the vascular tissues of the plant above water and  in contact with the atmosphere, providing an aerated root-zone and thus lowering the plant’s reliance on external oxygen diffusion through water and soil.  Oxygen transport into the root-zone through lenticles and arenchymous tissue has been measured between 2.08g O2/m2/d by  Brix and Schierup,1990; and 5 to 12g O2/m2/d by Armstrong etal  during 1990 in Phragmites australis grown in gravel beds. A second adaptation to flooding shared by some aquatic plants is the generation of adventitious roots from flooded stem tissues (Kozlowski ,1984).
The roots have potential to extract dissolved oxygen and plant nutrients from water where gases and nutrients may be available than in the anoxic soil zone. It has been observed that some aquatic plants can withstand much lower levels of anoxia in the root-zone than non-aquatic plant species, allowing an increased survival rate under extreme conditions such as peak flood levels, rainy periods or dormant periods.
In recent years there has been significant interest in the use of aquatic plants(macrophytes) for treating nutrient rich  wastewaters treatment systems usually incorporate retention ponds or wetlands in which selected aquatic plants such as Water hyacinth (Eichhornia crassipes),      Cat tails (Typha sp.) and Reeds (Phragmites spp.) are cultured in waste waters pumped through the system at a pre-determined flow rate. These plants have been found to be highly efficient in removing Nitrogen from primary and secondary sewage effluents. According to Meuleman, Beitman and Sheffer  who studied the water pollution control by aquatic vegetation of treatment wetlands in Netherlands reported dramatic changes in the water quality with particular reference to Phosphorus concentration which declined by more than 90%. In Netherlands several types of reeds and bulrush marshes, pond systems and ditch systems are used to reduce the eutrophication of polluted river water before it enters the wetland reserve. Hungarian expert Csilla Todoravices and his co-workers on the use of reeds (Phragmites australis) in wastewater treatment reported that the nutrient uptake in reed beds is on a large scale and denitrification can be performed also in Oxygen-poor  microsites; the process add up to a better retention  efficiency. The authors suggest that the reed beds can perform pollutant reduction on a similar rate to the reduction by conventional methods
The removal of Nitrogen and Phosphorus in treatment systems is the  result of a combination of biological  (denitrification, plant uptake, microbial immobilization) and Physical-Chemical process which include sedimentation, adsorption, precipitation etc.
Studies carried  on role of emergent aquatic plants Viz. Typha angustata and Phragmites communis under Kashmir conditions in treating water rich in Nitrogen and Phosphorus by Adnan in 2009 reported highest elimination for Nitrogen through Typha angustata (58%) and 77% of Phosphorus through Phragmites communis. In another communication the same author while studying the sanative role of aquatic plants in ecosystems of Kashmir concluded that the aquatic plants have a direct and indirect effects on the physic-chemical environment and provide important ecosystem functions by creating  conditions for volatilization of ammonia, precipitation of Phosphorus and calcium carbonate, enhancement of dissolved Oxygen and making cations and anions available besides improving the water quality through uptake of Nitrogen  and Phosphorus.
Floating aquatic plant are typically effective at reducing concentrations of biochemical oxygen demand and total suspended solids. Nitrate-nitrogen and Phosphorus removal can be considerably accomplished if the plants are harvested routinely. When floating aquatic plants are used for advanced wastewater treatment and nutrient removal organic loading should be kept below 35Kg/ha/d. Typical hydraulic loading rates are in the range of 2 to 15 cm/d (0.7 to 5 ha/1000m3/d). However it must be borne in mind that plant system have potential weakness that have limited their wide spread use
Azolla sp. Which has become an eye sore to our lake managers and has become a problematic weed is an indicator species  of  enrichment of waters with Phosphorus. The lake scientists should understand the fact that Azolla ha cyanobacterial endosymbionts that fix nitrogen and provide a nitrogen rich organic fertilizers or perhaps a forage resource. The N2-fixing cynobacterium of the Nostoc-Anabena  group acts as a symbiont. The N2-fixation potential of the association has been recognized as an N source. Azolla itself has a high  P-assimilation capacity and an ability to grow in N-limiting waters. As a result Azolla becomes a potentially good candidate for inclusion in the systems for increased efficiency and effectiveness. The recent studies by lake scientists have revealed the efficiency of removal of Nitrogen, Ammonia, Total Phosphorus to a tune of 91.7%, 99.6%, 98.5%  respectively  by floating aquatic plants viz. Eicchornia crassipes, Salvinia sps.
Adnan et. al. (2011) while studying the role of Lemna minor in phytoremediation of eutrophic water in Kashmir climatic conditions concluded that Lemna minor was able to sequester biologically important nutrients (nitrogen and phosphorus) both under in situ and ex situ conditions. L. minor showed high rate of nutrient uptake and preferentially reduced nitrogen by about   55 %. A high assimilation of nitrogen (13 mg/g on dry wt. basis) indicated a high content of protein also. Therefore, L. minor can be used as a protein-rich feed for fish, cattle and poultry. Moreover, this protein has a better array of essential amino-acids than most vegetable proteins and more closely resembles animal protein (Hillman & Culley, 1978). Thus, Establishment and maintenance of L. minor may be an effective management tool for improving quality of water.
The best way to exploit the aquatic plants for waste water treatment is through Treatment Wetlands which can provide a firm foundation from which to embark on a new and exciting technological journey. This is an age when environment is under increasing demands due to expanding populations and decreasing per capita energy supllies. Treatment wetlands can provide a double dose of Environmental protection when appropriately designed to optimize assimilation, habitat and public use functions. I welcome those who are considering options to enhance the environment through ecological Engineering.

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Lastupdate on : Fri, 3 Jun 2011 21:30:00 Mecca time
Lastupdate on : Fri, 3 Jun 2011 18:30:00 GMT
Lastupdate on : Sat, 4 Jun 2011 00:00:00 IST