Due to the rotational motion of the water, the levels of turbulence kinetic energy are increased leading to vigorous mixing and hence to uniform exposure to UV radiation. Since the UV lamps are arranged circumferentially around the outside of the quartz cylinder, pathogens that may become imbedded into suspended solids experience increasing probability of receiving UV dose sufficient for their activation since the UV light is radiated from all direction. In a conventional commercial system, where the water flow is linear and parallel to the UV lamps, embedded pathogens are more likely to exit the system before receiving adequate dose. At top of the cylinder, the treated water overflows as though over a radial weir into a collection trough and from there into an outlet tube either to be re-used elsewhere. The passage of the treated water above the weir is associated with significant entrainment of air into the water thereby elevating the percentage of dissolved oxygen while simultaneously lowering the water temperature. Testing of the UV reactor performance was carried out at the National Ornamental Research Site at the Dominican University of California . At this site, quarantine plant pathogens are studied in a mock nursery under field conditions that mimic those found in commercial nurseries . For the experiment,vertical farming tower for sale irrigation water from the research site was collected and stored for 7 days prior to the experiment to have enough volume to run the reactor at a flow of 2.2 l/s and to provide the endogenous population of bacteria, oomycetes and fungi for the test.
Tests were conducted on two separate occasions; in June 2013 and in October 2013. On the day of testing, this water was also spiked with P. ramorum zoospores to ensure its presence in the test water. P. ramorum zoospores were produced as described by Widmer . P. ramorum strain 1,418,886 was grown on CV8-agar at 20 °C for approximately three weeks. Sporangia production was induced by adding 15 ml of soil extract water. Release of zoospores was induced by cold shock, and then zoospores were harvested and counted using a hemacytometer. A total of 5 l of zoospore suspension was added to a water tank of volume 1893 l for a final concentration of 1.3 × 102 spores/ml. The UV reactor was placed in line with the effluent from the collection basin and was tested at a constant flow rate of 2.2 l/s. The tests were conducted under three separate conditions in which 4, 8 and 12 lamps were used. One liter of sample was collected from the influent of the disinfection system and one liter from each lamp condition to test samples for bacterial and fungal counts. The transmittance of the water was 76.4% UVT. Bacterial counts were made from cultures growing on Reasoner’s 2A, Acidified Dextrose Potato Agar , and PARPH-V8. One milliliter of each sample was plated in triplicate on each media type and cultured using standard methods. R2A is the preferred media for culturing bacteria found in treated or potable water sources, water sources with low concentrations of endogenous bacterial populations and long incubation times . ADPA is a media commonly used to culture fungal populations, but will also cultivate some bacterial populations.PARPH-V8 media contains pimaricin, ampicillin, rifamycin, pentachloronitrobenzene , and hymexazol and is a selective media designed to isolate Phytophthora sp. . The UV dose supplied by the system was determined by quantifying its ability to remove the MS2 virus . MS2 is a male-specific RNA virus that infects bacteria.
It has a similar structure to the polio virus and is widely used in water treatment research to assess the efficacy of a particular treatment method for virus removal . In the present application, water inoculated with MS2 to a given concentration was introduced into the UV system where it was exposed to UV light produced from UV lamps that varied in number from 2 to 12. Samples of the treated water were collected and delivered on the same day to Biovir Laboratories Inc. in accordance with the National Water Reuse Institute sampling guidelines . There, collimated beam testing was carried out according to standard methods to generate a dose response curve from which the actual UV dose delivered to the water was deduced. Results were obtained for water samples having UVT of 70 and 95%. The UVT was adjusted using instant coffee, an approved NWRI method . Each trial of the experiment used 1 l of MS2 with a titer of 1014 plaque forming units per milliliter for a final influent concentration of 108 PFU/ml. One liter of sample was collected for the collimated beam testing. The flow rate was kept constant at 2.2 l/s for all the tests.In water-treatment applications, reduction in bacterial counts achieved by a particular treatment method is measured in Blog reduction^ – the number of viable bacterial cells removed expressed on a logarithmic scale. For example, a 4-log reduction is a 10,000-fold decrease in the number of microorganisms present in the sample. A summary of the log reduction of the bacterial counts present in the irrigation water is presented in Table 1. Shown there are the results obtained from each of the bacterial culturing methods, and for three different lamp conditions corresponding to 4, 8 and 12 lamps. The results from the R2A and the PARPH culturing methods indicate that a minimum of 3.7 log reduction is achieved by the UV system. Low bacterial counts were seen on the APDA, because the acidification of the media suppresses bacterial growth.Microbial counts were evaluated using APDA to assess the fungal concentration and PARPH-V8 was used to determine the concentration of P. ramorum.
Whereas true fungi were present in the used nursery water as natural contaminants, P. ramorum was added as described above. One milliliter of each sample was plated in triplicate on each media type and cultured using standard methods. Fungal counts from the APDA media and PARPH media at each UV treatment are listed in Table 2. It can be seen there that the UV system removed about 75%, 91.7%, and 91.7% of fungal counts using 4, 8, and 12 UV lamps, respectively. It was also found that all lamp combinations of the UV system were able to inactivate 100% of the P. ramorum in the effluent.California’s water re-use policy Title 22 requires a demonstration of 5-log removal of MS-2, and the use of at least two reactors in series for redundancy to ensure a minimum level of safety in the system . Since only one reactor was tested,hydroponic vertical farm it must achieve at least 2.5 log removal of MS2 or a UV dose of 50 mJ/ cm2 . A dose of 50 mJ/cm2 is an approximate UV dose for 2.5 log removal. Figure 2a and b show the average log inactivation of MS2 and the average UV dose in the reactor with respect to change in lamp condition for the testing at UC Davis. From these figures, the reactor must operate with at least six lamps at a UVT of 95% and at least eight lamps at a UVT of 70% to achieve aminimum of 2.5 log removal of MS2. If only the 50 mJ/ cm2 UV dose condition is considered, then the UV reactor must operate with at least four lamps at a UVT of 95% and at least six lamps at a UVT of 70%. Figure 2c is a plot that shows the electric energy needed by the reactor to achieve one log of MS 2 inactivation for every 3785 l of irrigation water treated. As the UVT decreases from 95 to 70%, the energy required to inactivate a log of MS2 increases as more lamps would be required to deliver the necessary UV dose. Also, for the 95% UVT case, the energy required for a log removal changes very little when more than six lamps are used. Hence this would be the ideal number of lamps that would be needed for use in these conditions. Using the UVT of the water from NORS-DUC , the results of testing at the Davis were used to determine the UV dose supplied to the irrigation water. Using linear interpolation with the data from Fig. 2b, the UV dose supplied to the NORS-DUC irrigation water was 51, 61, 82, 100 mJ/cm2 for 4, 6, 8, and 12 lamps, respectively. Thus, to achieve a 5-log removal of MS2, two reactors each with four lamps would be needed to deliver the required UV dose. However, from a practical standpoint, since the percent of dissolved organics in the water can cause fluctuations in the UVT, it would be prudent to use six lamps. Achieving a 5-log removal in the irrigation water ensures that plant pathogens are not spread to the natural wildlife and renders the water suitable for reuse within the nursery. Additional low-cost safety measures can also be used in conjunction with UV treatment to help facilitate reuse within the plant nursery, such as filtration and settling. Since UV treatment is a physical process, pathogens embedded in soil particles may be shielded from treatment . In fact, Title 22 requires that the turbidity of the treated water be less than 5 NTU to account for this problem . Minimizing this risk and meeting Title 22 requirements can be achieved by first allowing heavy particles to settle out of the waste stream and then screening out suspended particles with a filter before treatment, typically with a nominal diameter of 1–10 μm.Livestock are an important livelihood source for over 900 million small scale producers in low-and middle-income countries , a source of nutrient-dense animal source foods and income for members of such households .
Livestock production systems in LMICs range from extensive mobile pastoral to semi-intensive urban and peri-urban small-scale production systems. Demand for livestock products is increasing worldwide, particularly in LMIC, fueled by population growth, urbanization, and rising incomes . Per capita consumption of ASF increased four to five-fold from the early 1960s to 2015 , with three fourths of this growth coming from LMIC . By 2050, consumers in LMIC will demand 107 million tons more meat and 5.5 million tons more milk than they did in 2005/2007 . The increase in demand pertains to both quality and quantity, especially as incomes rise from USD 2 to 10 per day, particularly among urban consumers who purchase livestock products from supermarkets .Though the livestock revolution can be an important opportunity for increasing income for small scale producers in LMIC, various constraints limit their ability to take advantage of it. Among many systematic, bio-physical and socio-cultural problems, limited access to quality feed is a major challenge across all production systems in LMIC . Feed affects livestock productivity, profitability, environmental impact, human food and nutrition security, animal welfare and ethics, and animal and human health . Financially, feed costs account for up to 70% of the total variable costs of livestock production and may reach 90% in more intensive systems . The global value of purchased compound feed relative to total animal output is about 30% on average for all production systems, and is 10% for cattle, 40% for pigs and 80% for poultry . Good quality feed improves livestock productivity, resulting in lower age at first calving and shorter inter-calving interval, thus increasing productive life and profitability . Proper feeding improves animal immunity , health, welfare, and reproductive performance; enables higher productivity under a given management regimen and contributes to environmental sustainability by converting energy and nutrients from land that is unusable by humans into highly nutritious food. Much of the feed consumed from livestock is derived from such areas or inedible agro-industrial byproducts. In fact, about 86% of the feed globally consumed by livestock is not edible by humans . Properly implemented forage-based systems including silvopastoral systems can reduce emissions from livestock . Proper feeding can reduce the methane emissions from livestock farming by increasing the ratio of feed used for production to that used for maintenance, also known as the maintenance dilution effect . This is critically important since feed , and enteric fermentation contribute to 45% and 39%, respectively, of the total emissions from livestock production . Lack of availability and access to quality feed continues to be the most important limitation to livestock production in LMIC. For instance, in six African and Asian focus countries of the Feed the Future innovation Lab for Livestock Systems, feeds and feeding-related issues were ranked consistently as the primary constraint to livestock production and consumption of ASF .