WASTEWATER: After four days of biological treatment, household wastewater from the toilet, kitchen and bathroom becomes clean water again. Microbacteria make a clean sweep of the dirt
There was a jug of water and a pot of coffee on the table when Stephen Djaba and Seth Okla from Solarland Co. Ltd. in Accra, Ghana, visited the Danish company BioKube. The aim of the meeting was to introduce the two Ghanaians to the secret of BioKube’s wastewater treatment plant that is based on a unique biological treatment concept. The water on the table could have been cleaned wastewater, but since most people have reservations about drinking this, it is normally reused for irrigation.
“Our concept for cleaning wastewater is based on a patented technology that is among the best in the world,” says Peter Taarnhøj, executive chairman of the board at BioKube. “The EU has established some general requirements in its Water Framework Directive on how clean wastewater needs to be purified, but in Denmark these requirements have been tightened to become the strictest of any EU country. It means that wastewater treatment plants developed in Denmark must meet these tightened requirements. And so does BioKube’s, at the same time as these requirements help to facilitate exports because our plants are always better than those of our foreign competitors.”
Small decentralised plants
Wastewater treatment plants are generally associated with large municipal or regional plants where wastewater from thousands of households, companies and factories are cleaned mechanically and/or chemically/biologically before it is returned to the environment. BioKube’s plants on the other hand, are noted for their small size and decentralised function.
“We supply plants that can handle wastewater from a single house with five people up to a large village plant,” says Peter Taarnhøj. “And almost everything in between, corresponding to treating between 1 and 1,500 cubic metres of wastewater every 24 hours.”
Bacteria eat the dirt
The heart of BioKube’s plant is a Danish patented system of bio-blocks – finely meshed PVC filters with a total surface area of several square kilometres. When wastewater is pumped through the filters, a natural flora of bacteria is formed, which feeds on the nutrients in the wastewater. By pumping air, and thereby oxygen, through the wastewater, the bacteria are given further opportunities to multiply and thus consume more nutrients. Before the wastewater is led through the bio-blocks, it passes through a pre-settlement tank where solid residues are collected.
“Of course this is a very simplified description of the principles,” says Taarnhøj. “But the point is that what happens in the plant is based on natural processes. In a brook in nature for example, the water is oxygenated when it runs quickly over densely packed obstacles, so it is clean and clear, while stagnant water become brackish and turbid. It is the former process we are imitating, with the addition of some high technology that helps to manage the process with precision.”
Communal toilets in Ghana
BioKube is not a product-manufacturing but a product-developing company. All components for the wastewater treatment plants are produced at sub-suppliers, and sales are handled through licensees or dealers. It is as potential licensees that Stephen Djaba and Seth Okla from Ghana are visiting BioKube.
“Very few houses in Ghana have their own toilet,” says Mr. Djaba. “There are communal toilets in residential areas, and our plan is to establish a BioKube pilot plant in connection with such a facility in Accra. Today all wastewater from communal toilets is collected in large tanks and transported by truck to the sea. Our vision is to make beaches into attractive tourist areas where people can swim. And to make the wastewater into clean irrigation water for our fields, and the sludge into valuable fertiliser.”
Local production
The production of the plants will be carried out locally in Ghana – in the same way as it is currently done in Denmark, Poland, France and Kuwait. BioKube has dealers in a large number of countries worldwide.
“Because of the strict environmental legislation in Denmark, we have had to develop the best technologies in the world,” says Peter Taarnhøj. “It is that knowledge and competence we are selling. But the physical production itself will be carried out locally. And the potential is gigantic. In Denmark alone, around 90,000 isolated properties must have wastewater cleaning before 2013, according to the EU Water Framework Directive. In Europe, the figure is around 25 million. And then I dare not think of the global figure. But for the sake of our future water resources, the problem needs to be tackled. It cannot happen fast enough.”
