The response of lichen growth to additions of distilled water, rainwater and water from a rock surface

Three lichen species were wetted in the field with distilled water, rainwater or water which had run off a rock surafce, during July 1974 to February 1975. The radial growth rate of Parmelia glabratula ssp. fuliginosa was not influenced by the wetting treatments. The radial growth rate of P. conspersa with the distilled water was greater than the control, rainwater and runoff treatments. The radial growth rate of Physcia orbicularis was lower with rainwater and runoff treatmentss than the control and distilled water treatment. These results may be explained by the effect of wetting on the carbon balance of the lichens and by the influence of water chemistry.

A greenhouse integrating desalination, water saving and rainwater harvesting for use in salt-affected inland regions

This study proposes a new type of greenhouse for water re-use and energy saving for agriculture in arid and semi-arid inland regions affected by groundwater salinity. It combines desalination using reverse osmosis (RO), re-use of saline concentrate rejected by RO for cooling, and rainwater harvesting. Experimental work was carried at GBPUAT, Pantnagar, India. Saline concentrate was fed to evaporative cooling pads of greenhouse and found to evaporate at similar rates as conventional freshwater. Two enhancements to the system are described: i) A jet pump, designed and tested to use pressurized reject stream to re-circulate cooling water and thus maintain uniform wetness in cooling pads, was found capable of multiplying flow of cooling water by a factor of 2.5 to 4 while lifting water to a head of 1.55 m; and ii) Use of solar power to drive ventilation fans of greenhouse, for which an electronic circuit has been produced that uses maximum power-point tracking to maximize energy efficiency. Re-use of RO rejected concentrate for cooling saves water (6 l d-1 m-2) of greenhouse floor area and the improved fan could reduce electricity consumption by a factor 8.

The fabrication of biodegradable nanospheres from novel hydroxalkanoates for the delivery of actives of pharmaceutical and agricultural interest

This work describes the fabrication of nanospheres from a range of novel polyhydroxyalkanoates supplied by Monsanto, St Louis, Missouri, USA for the delivery of selected actives of both pharmaceutical and agricultural interest. Initial evaluation of established microsphere and nanosphere fabrication techniques resulted in the adoption and optimisation of a double sonication solvent evaporation method involving the synperonic surfactant F68. Nanospheres could be consistently generated with this method. Studies on the incorporation and release of the surrogate protein Bovine Serum Albumin V demonstrated that BSA could be loaded with between 10-40% w/w BSA without nanosphere destabilisation. BSA release from nanospheres into Hanks Balanced Salts Solution, pH 7.4, could be monitored for up to 28 days at 37°C. The incorporation and release of the Monsanto actives - the insecticide Admire® ({ 1-[(6-chloro-3-pyridinyl)methyIJ-N-nitro-2-imidazolidinimine}) and the plant growth hormone potassium salt Gibberellic acid (GA3K) from physico-chemically characterised polymer nanospheres was monitored for up to 37 days and 28 days respectively, at both 4°C and 23°C. Release data was subsequently fitted to established kinetic models to elaborate the possible mechanisms of release of actives from the nanospheres. The exposure of unloaded nanospheres to a range of physiological media and rural rainwater has been used to investigate the role polymer biodegradation by enzymatic and chemical means might play in the in vivo release of actives and agricultural applications. The potential environmental biodegradation of Monsanto polymers has been investigated using a composting study (International Standard ISO/FDIS 14855) in which the ultimate aerobic biodegradation of the polymers has been monitored by the analysis of evolved carbon dioxide. These studies demonstrated the potential of the polymers for use in the environment, for example as a pesticide delivery system.

Stand-alone groundwater desalination system using reverse osmosis combined with a cooled greenhouse for use in arid and semi-arid zones of India

In many areas of northern India, salinity renders groundwater unsuitable for drinking and even for irrigation. Though membrane treatment can be used to remove the salt, there are some drawbacks to this approach e.g. (1) depletion of the groundwater due to over-abstraction, (2) saline contamination of surface water and soil caused by concentrate disposal and (3) high electricity usage. To address these issues, a system is proposed in which a photovoltaic-powered reverse osmosis (RO) system is used to irrigate a greenhouse (GH) in a stand-alone arrangement. The concentrate from the RO is supplied to an evaporative cooling system, thus reducing the volume of the concentrate so that finally it can be evaporated in a pond to solid for safe disposal. Based on typical meteorological data for Delhi, calculations based on mass and energy balance are presented to assess the sizing and cost of the system. It is shown that solar radiation, freshwater output and evapotranspiration demand are readily matched due to the approximately linear relation among these variables. The demand for concentrate varies independently, however, thus favouring the use of a variable recovery arrangement. Though enough water may be harvested from the GH roof to provide year-round irrigation, this would require considerable storage. Some practical options for storage tanks are discussed. An alternative use of rainwater is in misting to reduce peak temperatures in the summer. An example optimised design provides internal temperatures below 30EC (monthly average daily maxima) for 8 months of the year and costs about €36,000 for the whole system with GH floor area of 1000 m2 . Further work is needed to assess technical risks relating to scale-deposition in the membrane and evaporative pads, and to develop a business model that will allow such a project to succeed in the Indian rural context.