Moses hit a rock to produce drinking water for the Israelites in the Sinai desert - but today, much of the world's population is still thirsty. A billion people lack easy access to safe drinking water, and a million children die each year from polluted water. Israel - whose chronic water deficits are more problematic than its citizens' bank overdrafts - has been forced to use ingenuity in making its water resources go farther. Necessity has proved the mother of invention at the Hebrew Agricultural, Food and Environmental Quality Sciences in Rehovot. The university (and the Israel21c Web site) recently hosted journalists to explain - in honor of the UN's World Environment Day on June 5 - what its researchers are doing to benefit the globe's ecology and fight desertification. The verdant campus near the Weizmann Institute has 2,300 students (there were only 21 when the agriculture faculty was founded in 1942) pursuing degrees in agriculture, nutrition, plant sciences and veterinary medicine. Faculty dean Prof. Eli Feinerman, an expert in agricultural economics and management, noted that because there is not enough rain for a growing, ever-modernizing population, wastewater has to be exploited for irrigation and other purposes so that potable water can be used for drinking and food manufacturing. Since farmers need water mostly during the summer, processed wastewater must be stored the rest of the year in reservoirs, which are costly to build and occupy expensive land. And reservoirs cannot be built over aquifers in order to avoid polluting precious fresh water. But the system is still more economical than importing water from Turkey, or even desalinating sea water. Feinerman noted that 55% to 60% of water used in households, businesses and manufacturing is returned to the system as sewage, and 80% of that is currently processed in waste-treatment plants. When processed effluent is used for agriculture, not only do farmers benefit but so do the municipalities, which want to get rid of their sewage. In some municipality-agricultural sector arrangements, farmers get the processed wastewater free if they are willing to pay for transport. Treated wastewater can also be used to renew polluted rivers by flowing through them and then being collected at the end for use in irrigation. THE DEAN noted that today there are 32 waste treatment plants (compared to only eight in 1995), mostly built by the national water carrier Mekorot at a cost of $1.2 billion. These produce 360 million cubic meters of water annually, and Feinerman predicted that by 2010, half of all wastewater will be recycled - the highest percentage in the world. Sewage treated by the most efficient technology can even be drunk safely, Feinerman added, though he acknowledged that "no one would be willing to drink it for psychological reasons." Wastewater is more saline than fresh water, and since many crops are sensitive to salt and other minerals such as boron, these must be removed. At the same time, treated wastewater has higher levels of nutrients such as phosphorus and nitrogen, and these are a boon to farmers. A year ago, the government received recommendations on wastewater treatment from the Inbar Committee, which urged that standards (involving 38 parameters) for treated water be raised enough so that all crops can be irrigated. But, said Feinerman, these higher standards have not yet become mandatory because no one - not the municipalities (which would prefer to let their sewage flow into the nearest stream or sea), the farmers or the government - was willing to pay the higher costs. PROF. AVNER ADIN, founder and president of the Israel Water Association and an expert in environmental health at the Rehovot faculty, noted that even though we take it for granted when it flows out of our taps, water is actually a global business - a $400 billion business, with an 8% annual growth rate. Among the techniques Adin has been involved in are surface- and sub-surface drip irrigation, seawater desalination, membrane filtration, soil-aquifer treatment, solar ponds and contact filtration. He even established his own startup company for research and development, and has taught engineers and field operators in the public sector and industry. There are numerous ways to treat wastewater, said Adin, who has provided advice to the World Health Organization, South Africa, Thailand, India, Egypt, Mexico, Senegal, Japan and Greece. Wastewater, he said, can be filtered, removing soil, sand, algae, bacteria and other harmful particles which bear electrical charges. The problem is that, because they all have the same charge, these particles repel each other rather than sticking together to become larger gobs that can easily be removed. Low-level technology forces wastewater through sand. This technique has been used around the world for many years, but is not efficient because a biological film forms that prevents particles from moving through. HU researchers developed a technology that removes the upper surface of sand, washes it and returns it to the system - an approach that is cheap and uncomplicated enough for developing countries. The HU has helped Senegal in Africa to build a biological treatment plant based on its investigations into using treated wastewater for irrigation, and the Italian government is funding the project. More expensive and complex filtration systems use membranes made of man-made polymers with tiny pores that let the water pass but hold back most of the particles. But a major problem is that the tiny particles can clog up the pores. To deal with this, HU scientists on the Rehovot campus have developed a flocculation (coagulation) system in which the wastewater is "fed" with iron or aluminum ions instead of undesirable chemicals. Electrodes are inserted into the wastewater and a weak current is passed through, causing the ions to neutralize and the particles to flocculate for easy removal. "The sludge settles and the effluent goes for biological treatment. It is compact, modular and efficient, and it even kills bacteria," Adin said. "It has great potential in North America, Europe and China. There is already a treatment plant in Gan Yavne based on our patented technology. Prof. Oded Shoseyov of the faculty's institute of plant science and genetics in agriculture - who personally holds more than a dozen patents - discussed not wastewater but the depletion of forests. Even though the computer revolution was expected to reduce the need for paper, Shoseyov said that in the past 20 years, demand has increased dramatically. People are still reading newspapers and books, and when they sit down in front of their computers, they want to print everything out. In addition, product packaging needs continue to grow. As a result, across the globe, forest areas five times the size of Israel are wiped out by logging each year. The loss of trees reduces photosynthesis and increases the production of greenhouse gases that lead to global warming, while the lack of viable tree roots causes topsoil to blow away and deserts to spread. "Cellulose has become a very important commodity in the past 15 years," said the HU plant researcher. "It has become very important to promote and speed up cellulose production." And that is what Shoseyov and his colleagues have managed to do. They focused on genes, and were the first to clone and isolate one called Cel1. Overexpression of the gene is beneficial for fast growth, as it loosens rigid cell walls, thereby increasing the rate of growth of forest trees and even crops such as potatoes. They have patented this process for a company named CBD Technologies located in Rehovot's science park. The company has already signed agreements with large forestry firms in Brazil and Thailand; transgenic eucalyptus trees were planted recently in Brazil as part of a field trial. Wood production is up to 370% higher, compared to increased rates of merely 15% from conventional technologies. The quality of transgenic wood, Shoseyov says, is even better than that of ordinary trees. Asked about fears, especially in Britain and Europe, regarding the "dangers" of genetic engineering of plants, Shoseyov said: "There is no technology with no risk, but we think that if we take precautions, the technology can be used safely. Doing nothing when forests are being wiped out is much worse. I wouldn't genetically engineer every species; I wouldn't produce fluorescent rabbits, as there is no need for this. We used eucalyptus trees because their seeds do not spread beyond their area. Five meters away, there are no natural seedlings, so there is no danger that transgenic eucalyptus trees can affect other species." FINALLY, Dutch-born Prof. Jaap van Rijn of the animal sciences department unveiled a unique indoor filtration system that uses bacteria to raise marine fish. This, he said (while climbing the stairs to a small vat that can be used to raise some 400 sea bream or sea bass), is an environment-friendly alternative to the aqua-culture cages commonly used around the world, which damage coral reefs and coastal waters. Only two meters in diameter and one meter deep, the vats merely have to be topped off from time to time to replace water lost by evaporation. The process has been patented by the HU's research and development arm, Yissum Ltd., and is being commercialized by a company near Karmiel. Van Rijn said the technology allows the natural growth of certain kinds of bacteria in the vats, depending on the rate at which the water circulates. The new technique makes it possible to raise marine - as well as fresh water - fish in vats containing tap water which doesn't have to be changed. Ornamental sea fish made popular by the animated movie Finding Nemo and sought by aquarium owners can also be raised. Come to think of it, the agriculture faculty's scientists and their exciting discoveries relating to fish, forests and wastewater would be good raw material for a movie.