Fukuoka is urban areas have geographical-s-problems of the type not blessed with big water systems, such as a first grade river, and has been hit by the water shortages often in the past.Then there is the necessity for development of water resources which address demand, and it was determined that a Reverse Osmosis (RO) desalination plant be used for the Fukuoka District Waterworks Agency. This plant is required to be “Low operating cost” and “High quality reliability”. The design conditions are to produce water of 50,000 m3 per day with RO desalination system with a recovery is ratio of 60%. In addition, this plant is specified to produce low TDS (less than 200 ppm) permeate steadily. It is aimed at high recovery run of sea-water desalination system for “low cost”. Feed flow rate and brine flow rate can be reduced with high recovery run, and the quantity of pretreatment becomes less and the amount of electric-power consumption can also bereduced. It is expected that the Fukuoka seawater desalination plant, when it goes on stream in 2005, will provide water actively as a trump card of the new development for water resources in the Fukuoka district.
Proper pretreatment is the most important faftor for stable SWRO plant operation. MF/UF membrane treatment is effective in improving of feed water quality to SWRO. And befause of recent cost reduction of MF/UF membrane and high refovery ratio of SWRO unit, the water production cost is expected to be reduced than that of the SWRO unit with conventional pretreatment system. Recentresearches on MF/UF membrane and other treatments for pretreatment of seawater reverse osmosis are reviewed.
For the reduction of boron concentration in SWRO (Sea Water Reverse Osmosis) permeate water, BWRO (Brackish Water Reverse Osmosis) is used as a post treatment In this study, the behavior of boron in this BWRO system and the effbct of operation parameters on the permeabi1ity of water, salt and boron are invesdgated using a test unit with 8-inch modules, The results are as follows: Firstly, the effect of concentration po1arization on module performance is not clear in the case of high flux with low feed rate.Secondly, the pH of pemleate water showed complicated behavior, Thirdly, the permeabilityof non-ionic boron isalmost constant in the pH range of 9 to 10.Finally, high recovery rado (95%) operation was possible with effective boron removal.
The major components, trace elements, ferrocyanide, and viable cell number in common brands of salt were measured. Many types of domestic salt had a significant content of bittern, a lower purity of sodium chloride and less insoluble matter than the imported types. Some imported solar salts containedsignificant insoluble matter which resulted in contamination by heavy metals. Three of the analyzed samples included more than 0.5 mg/kg of arsenic (the maximum limit according to the Codex Standard for Food Grade Salt) and two samples contained lead or cadmium, Samples with high concentrations of copper, chromium, nickel, andzinc were also found. None of viable cells were detected in all the measured samples, and ferrocyanide ion was contained in four of the imported samples.
In the Pak Phanang Basin of southern Thailand, the Nipa palm (Nypa fruticans wurmb.) grows naturally in an area of approximately 3,200 ha. Economically, coastal villagers in the basin earn their income from the palm in several ways, most importantly in Nipa sugar production. The production of 1,030 kg/ha of sugar per month with 8 tappable months per year is standard for this area. Nipa sap is the source of sugar, its content was reported to be 14 to 17 percent sucrose. Sap is generally collected from the mature fruit stalk (infructescence) after the almost full-grown fruiting head of the plant has been cut. Sap flow, however, depends on preparationof the stalk. To stimulate the flow, the stalk is beaten 40-50 times daily for 3 days and then this is stopped for 10 days. The beating cycles are then repeated consecutively for a second and a third time. Tapping begins by removing a thin end slice of the fruit stalk about 1-2 mm thick. The freshly cut stalk end is inserted into a hole in a bamboo container to collect the sap. A skilled tapper is able to tap as many as 100 stalks per day. It is estimated that a normal tapped stalk can produce about 0.7 l of sap daily. Research on sap flow stimulation has shown a relation between varying levels of beating the stalk and rates of sap flow. The conversion rate of sap to sugar by boiling and evaporation is on average, 100 l sap: 21 kg sugar.