Use of nitrogen-and phosphorus-based synthetic fertilizers shows an increasing trend, but this has led to largescale influx of reactive nitrogen in the environment, with serious implications on human health and the environment. On the other hand, phosphorus, a non-renewable resource, faces a serious risk of depletion. Therefore, recovery and reuse of nitrogen and phosphorus is highly desirable. For nitrogen recovery, an ion exchange/adsorption-based process provides concentrated streams of reactive nitrogen. Bioelectrochemical systems efficiently and effectively recover nitrogen as NH 3 (g) or (NH 4 ) 2 SO 4 . Air stripping of ammonia from anaerobic digestate has been reported to recover 70-92 % of nitrogen. Membrane separation provides recovery in the order of 99-100 % with no secondary pollutant in the permeate.With regard to phosphorus (P) removal, physical filtration and membrane processes have the potential to reduce suspended P to trace amounts but provide minimal dissolved P removal. Chemical precipitation can remove 80-99 % P in wastewater streams and recover it in the form of fertilizer (struvite). Acid hydrolysis can convert recovered P into usable phosphoric acid and phosphate fertilizers. Physical-chemical adsorption and ion exchange media can reduce P to trace or non-detect concentrations, with minimal waste production and high reusability. Biological assimilation through constructed wetlands removes both N (83-87 %) and P (70-85 %) from wastewaters, with recovery in the form of fish/animal feeds and biofuel. The paper discusses methods and important results on recovery of nitrogen and phosphorus from wastewater.
A decade since the availability of Mycobacterium tuberculosis (Mtb) genome sequence, no promising drug has seen the light of the day. This not only indicates the challenges in discovering new drugs but also suggests a gap in our current understanding of Mtb biology. We attempt to bridge this gap by carrying out extensive re-annotation and constructing a systems level protein interaction map of Mtb with an objective of finding novel drug target candidates. Towards this, we synergized crowd sourcing and social networking methods through an initiative ‘Connect to Decode’ (C2D) to generate the first and largest manually curated interactome of Mtb termed ‘interactome pathway’ (IPW), encompassing a total of 1434 proteins connected through 2575 functional relationships. Interactions leading to gene regulation, signal transduction, metabolism, structural complex formation have been catalogued. In the process, we have functionally annotated 87% of the Mtb genome in context of gene products. We further combine IPW with STRING based network to report central proteins, which may be assessed as potential drug targets for development of drugs with least possible side effects. The fact that five of the 17 predicted drug targets are already experimentally validated either genetically or biochemically lends credence to our unique approach.
The use of silver in consumer products and its subsequent leaching in greywater show an increasing trend. Silver recovery is not only commercially lucrative but also an environmental necessity. Trace concentration of Ag + and high concentration of other competing cations (Na + , Ca 2+ , Mg 2+) in a typical laundry wash water makes the separation process challenging. The use of ion-exchange resin with thiol group in its chain offers a potential solution due to its high selectivity for silver. This work successfully recovers silver (>90%) as high purity grade Ag 2 S powder (>99%) from synthetic greywater solution using a commercially available resin, Ambersep GT74, in a fixed-bed column mode. The regeneration process in the work has been optimized with respect to the solution pH and thiourea concentration (0.5 M thiourea concentration at pH 1). The resin and the regenerant have been used in multiple cycles (4 times) without compromising on their performance. The study successfully demonstrates a closed-loop sustainable scheme by reusing and recycling all the raw materials to the point of exhaustion with no chemicals/toxic released into the environment.
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