Between the 26th and 28th of April the annual Engineering with Membranes was held in Singapore organised by the Singapore Membrane Technology Centre (SMTC). The main goal of the conference was to share knowledge on recent advances in membrane science and technology. Leading membrane specialists from around the world gave a total of 70 lectures covering desalination, reclamation & resource recovery, molecular separation, membrane fouling, gas separation, pre-treatment, industrial & bioprocess application and membrane monitoring. The Dutch representative at this conference was Dr. Emile Cornelissen, senior researcher at KWR, who presented his research on controlling Reverse Osmosis (RO) fouling after minimal pre-treatment. His main conclusion was that the 1-step RO scenario was approximately 20% lower in costs than the Ultrafiltration (UF) – RO scenario. Air/water cleaning is effective to control clogging, while lowering flux values results in less membrane fouling.
The Giant Snakehead, channa micropeltes, is one of the largest snakehead species. Lengths over 1 meter are regularly encountered. They are found throughout South-East Asia and have been introduced elsewhere in the world where they are considered an invasive species. Giants Snakeheads are highly adaptable and have the ability to crawl onto land and breath air in muddy conditions. They possess a primitive lung, located behind the gills, which it uses to gulp air. It can therefore travel short distances over land!
These fish are ferocious predators and will chase down anything that will fit in their mouth. They have very sharp teeth that can rip fish into half. It should therefore only be kept in aquaria with similar sized fish, but even then it is risky. Despite its aggressive nature, it is a very beautiful fish with juveniles having distinctive bright lines across their body. As the fish grows older they develop a pattern comprising a broad, dark longitudinal stripe. Adults will defend their brood at all costs and have occasionally injured humans.
Pictures above is thanks to Zooish from Zoochat
One of Singapore’s four national “water taps” is to reclaim water from wastewater. After years of research, the Public Utilities Board (PUB), Singapore’s national water agency, started to supply high quality reclaimed water, referred to as NEWater. The majority of NEWater is supplied to industries for non-potable purposes. The rest is discharged into reservoirs for indirect potable use. Currently NEWater meets 30% of Singapore’s current water demand, and there are plans to increase this to 50% by 2060. At this moment there are four NEWater treatment plant in service (Bedok, Kranji, Ulu Pandan and Changi). NEWater is produced from treated sewage, termed “used water”, that is further purified in three different steps:
- Microfiltration (MF) is the first step in the NEWater production. The treated used water is passed through membranes to filter out and retained on the membrane surface suspended solids, colloidal particles, disease-causing bacteria, some viruses and protozoan cysts.
- The second stage of the NEWater production process is known as Reverse Osmosis (RO). In RO, a semi- permeable membrane is used. The semi-permeable membrane has very small pores which only allow very small molecules like water molecules to pass through. Consequently, undesirable contaminants such as bacteria, viruses, heavy metals, nitrate, chloride, sulphate, disinfection by-products, aromatic hydrocarbons, pesticides etc, cannot pass through the membrane.
- The third stage of the NEWater production process acts as a further safety back-up to the RO. In this stage, ultraviolet or UV disinfection is used to ensure that all organisms are inactivated and the purity of the product water guaranteed (PUB).
(Reverse osmosis membranes)
The Tiger Barb is a beautiful fish that is found in clear or turbid shallow waters of moderately flowing streams. They live in Indonesia and Borneo and their average lifespan is about 6 years. It has four very distinctive black stripes, which resembles the pattern of a tiger. These fish are very active and playful, which makes them fun to watch. They are also fairly hardy and easy to keep provided that frequent water changes regularly occur. The species does need company, and will do best with 6 or more in a group. Having schools of 20+ will make these Tiger Barbs look even more spectacular! DO NOT house these fish with long-finned or slow-moving fish as Tiger Barbs are well known fin-nippers! Gouramis and Anglefish should not be housed together with Tiger Barbs. When Tiger Barbs are kept in larger groups they tend to be less aggressive as they are more busy chasing each other. I personally like to house Tiger Barbs with other fish of Sumatran biotope, such as Bala Shark and Clown Loach.