Anaerobic technology, available in Australia from CST Wastewater Solutions is a proven method to clean wastewater and generate green electricity.
Early adopters of anaerobic technology used to convert wastewater into green energy are now reaping millions of dollars a year in benefits by replacing fossil fuel, producing less pollution as a result, and achieving much cleaner effluent water in the bargain.
Advanced anaerobic technology from Global Water Engineering can be used globally wherever industry has a biological waste stream or wastewater with high organic carbon or COD (chemical oxygen demand) of natural origin that can be broken down into biogas by anaerobic bacteria.
Proven at more than 300 food, beverage, agro industry and processing plants worldwide, the technology simultaneously cleans the water to high discharge standards while producing biogas (methane) to generate green electricity for fuel boilers and other factory plant fuel consumers.
GWE’s anaerobic technology has been implemented by a major producer of native tapioca starch, sweeteners and modified starch in Thailand within its wastewater plant to produce up to 70,000Nm³ a day of biogas at 70% methane. This corresponds with roughly 43,750kg a day of heavy fuel oil, worth $A 12.2 million a year.
Operating with a capacity of 6000m³ a day of wastewater, containing 150,000kg per day of COD, the Corn Products International plant, commissioned in 2007, also achieves high effluent purification levels of more than 95%, reducing COD loads from 25,000 mg/l COD influent to 1250 mg/l effluent.
According to Global Water Engineering CEO Mr Jean Pierre Ombregt, anaerobic technology is particularly brilliant for food, beverage and agro industry applications. Though green energy generation from wastewater doesn’t get as much attention as other green technologies such as wind power, early adopters of the technology are reaping benefits year after year.
He explains that the energy yield from the anaerobic digestion of the starch factory’s wastewater is more or less equal to the fuel demand for the mill’s production, making the factory as good as self-sufficient for its fuel energy needs. The savings in such projects are permanent and ongoing, while the cost of typical installations can be repaid within a couple of years, sometimes even a year.
Anaerobic digestion is a biological process whereby bacteria break down organic material into more basic compounds without requiring oxygen as a component of the process. Modern anaerobic processes vastly concentrate the process in environmentally harmonious closed reactors, operated under ideal temperature and process control to optimise waste consumption and, in the process, generate large quantities of methane from the organic materials in the wastewater.
Mr Ombregt points out that one ton of COD digested anaerobically generates 350Nm³ of methane, equivalent to approximately 312 litres of fuel oil, or about 1,400 kWh of green electricity.
Anaerobic digestion facilities have been recognised by the United Nations Development Programme as one of the most useful decentralised sources of energy supply, as they are less capital-intensive than large power plants. They can also benefit local communities by providing local energy supplies and eliminate the need for large and often smelly and environmentally challenging anaerobic lagoons.
Mr Ombregt observes that most industries have mainly been focusing on treating their effluent to meet local discharge standards at the lowest possible investment costs. By doing so, wastewater treatment installations have only generated additional operating costs and have never been seen as revenue generators.
However, applying anaerobic wastewater treatment sheds a whole different light on the cost structure of wastewater treatment infrastructure as it can now actually become a substantial additional source of income for many factories and processing plants throughout the world, including the food, beverage and agro industries.