The Biogas Boom

Narin Kajohnchalearmsak couldn’t be happier with the $1.3 million investment he made to his tapioca starch factory 9 years ago. He installed what’s called an anaerobic fixed film reactor (AFFR) to process wastewater into biogas. Within 3 years of completion, the reactor had saved his Chol Chareon Company $2 million in fuel oil costs.

Chol Chareon is one of Thailand’s largest tapioca starch factories, exporting about 500,000 tons of tapioca starch annually, generating $6 million in revenue. It is one of four such facilities the National Center for Genetic Engineering and Biotechnology (BIOTEC) and King Mongkut’s University of Technology Thonburi (KMUTT) worked with to deploy the novel wastewater treatment process in 2001.

The AFFR technology is the result of research undertaken in 1984 by two scientists, Morakot Tanticharoen and Sakarindr Bhumiratana, who were then working at KMUTT.

Back then, biogas, and renewable energy generally, did not receive the attention they are getting now, nor did they offer the CO₂ savings currently possible, adds Morakot. But increasingly such technologies are being seen as the industry standard for factories like Chol Chareon in Thailand.

The AFFR method utilizes a net-like device fabricated with local materials that is layered inside an anaerobic reactor to trap and concentrate the microorganisms so that they can consume the wastewater’s organic compounds.

Bacteria inside the reactor break down the wastewater’s carbohydrates, proteins and fats into smaller organic compounds, releasing acetic acid and hydrogen as byproducts. Methanogenic bacteria then generate methane and CO₂, which are captured and used as biogas.

The process takes much less time and requires far less space than an open-pond system. Moreover, the treated water is of sufficient quality to be safely used for irrigation. AFFR reduces the chemical oxygen demand (COD) level in Chol Chareon’s wastewater by more than 90 percent, from 24,000 mg/L to just 2,000 mg/L.

“The economics were far too enticing to pass up,” says Narin. When he first considered AFFR, he had $700,000 in annual fuel oil expenses. Had he delayed, these costs likely would have doubled or tripled as global oil prices increased.

“Environmentally speaking, AFFR efficiently treats the wastewater to a point that odors are nearly gone and the water is much cleaner than what we produced before,” says Anuwat Ruethaiyanon, managing director of Northeast Starch Company, another early AFFR adapter.

The AFFR process allows Northeast Starch to generate 17,000 cm2 of biogas daily, replacing about 6,900 kilos of liquefied petroleum gas, realizing an annual savings of about $460,000.

Eleven AFFRs are now in operation in food processing factories, says Morakot, and the process has spawned a sister technology. EcoWaste, an agricultural waste management center operated jointly by KMUTT and BIOTEC, has developed what’s called an Anaerobic Hybrid Reactor (AHR), which combines AFFR with a granular sludge system.

A new AHR installation at the Tha Chana Palm Oil Company is slated to treat 230 m³ of wastewater with a COD of 90,000 daily and to generate 1.31 m³ of biogas annually.

The success of these technologies has motivated the Thai government to offer additional incentive programs, including subsidies and soft loans to encourage more widespread adoption of the equipment. The government intends to introduce AFFR, AHR, and other biogas technologies to all 60 tapioca starch factories and all 40 of the country’s palm oil factories. Additionally, many preserved-fruit factories are now shifting their open ponds to biogas technologies.

Pawinee Chaiprasert, a researcher with EcoWaste, says one of the main reasons for the increased interest in the technology is the potential for capturing marketable carbon credits. The CO₂ savings from replacing fossil fuel inputs with biogas may render factories eligible for carbon credits offered through the United Nations’ Clean Development Mechanism. Companies in developed countries can purchase these credits to offset their CO₂ emissions.

In 2009, the average price per ton of carbon on the European Climate Exchange was €12.25. Once certified, a facility like Chol Chareon might be able to claim up to 24,000 tons in credit annually, Narin estimates. Presently, more than half of 94 CDM projects at different stages of approval by Thailand’s Greenhouse Gas Management Organization are tapioca and palm oil factories.

Thailand’s wastewater treatment methods are also finding their way overseas. In 2005, Nigeria’s “Cows to Kilowatts” program received a United Nations Development Program SEED award for eliminating environmentally hazardous effluent from slaughterhouses using AHR technology designed by EcoWaste. “One never knows where one’s research might lead,” says Marakot with a smile.