A better way: The open pond treatment system, currently used in most palm oil mills, leads to discharge of greenhouse gases as the waste degrades. New treatment technologies aim to reduce these emissions.

19/01/2015 (The Star) - Exctracting the oil from palm fruits is not exactly a straightforward process. From sterilising, stripping, digesting and pressing of the fruit, to the oil clarification, purification, vacuum drying and packing, it involves a number of steps.

The amount of water needed for these palm oil mill operations is thus, a concern. An average of about 1.5m³ of water is reportedly needed to process one tonne of fresh oil palm fruits. Half of this liquid ends up as palm oil mill effluent (POME).

POME comprises water-soluble components of palm fruits as well as suspended materials like fibre and oil residues. While biodegradable, POME is acidic and has an extremely high biochemical oxygen demand (BOD). BOD is the amount of dissolved oxygen needed by organisms in a body of water to break down organic material present. A high value indicates organic pollution, which decreases oxygen supply and negatively affects aquatic life.

Providing a solution

The problem has led to the need to develop wastewater treatment technologies for use in palm oil mills. Ronser Bio-Tech for example, has introduced a plant that effectively treats POME for a cleaner discharge.

Company chairman Woo Min Fong says its pilot plant uses patented technologies developed by Prof Zhang Zhen Jia of the Shanghai Jiaotong University (SJTU).

“Ronser, being a specialist in high organic content industrial wastewater treatment, together with SJTU, has successfully designed and built this treatment system in Labu (Negri Sembilan),” Woo states.


Ronser Bop-Tech's plant in Labu not only treats mill effluent, but recovers valuable by-products from it.

In the past, partially treated or even raw POME was discharged into rivers. This raises environmental concerns. Many small waterways have been devastated by such discharges. Under the Environmental Quality Act 1974, the BOD limit of POME was set at 100 parts per million (ppm). This was recently tightened by the Department of Environment to 20ppm.

Ronser’s system allows for POME to meet the required levels. It uses a combination of a core aerobic and anaerobic system to consistently achieve the BOD value of 20ppm and below.

In the treatment process, POME is first channelled into the AnaEG reactor. As it flows upwards, organic matter is biodegraded using an anaerobic process. Organic acid plus methane gas is formed, and 70% to 95% of waste compounds are removed. In the BioAX process, a high-efficiency bio-membrane further filters the wastewater. The technology substantially reduces sludge quantities, and thus, its handling cost.


Raw palm oil mill effluent (POME) can have a biochemical oxgyen demand content of up to 27,0000ppm. Ronser's proprietary technology allows for treated POME to comply with the Department of Environment's requirement of 20ppm.In fact, the end results is water so clear that it can be reused.

AnaEG is touted as being particularly efficient for problematic wastewater with very high organic content. BioAX is faster and more efficient than the conventional activated sludge process. It also occupies a relatively small land area compared to the conventional open-pond treatment system. Only 408sqm is needed to meet demands to treat 1,000m³ per day.

A step further

While the pilot plant in Labu has been completed and duly certified by the Malaysian Palm Oil Board in June, Ronser has now re-launched it to implement additional projects in the research and development of the technology. The new advancements allow for the recovery of various by-products generated during the process. For instance, recovered magnesium and potassium can be used as organic fertiliser.

In theory, the system should be able to generate biogas (mainly methane) at a rate of 150m³ per hour. If properly captured, methane can be converted into electricity and heat.

That apart, the system is said to produce wastewater that is good enough for boiler use. Other miscellaneous by-products can benefit other industries like the aquaculture industry.

Ronser acknowledges that the challenges have always been with getting palm oil millers to accept the system. With the added economic benefits of recoverable by-products, the company hopes that it will be even more marketable.

“We just launched our latest wastewater system for palm oil mills at the Seminar On Palm Oil Milling, Refining, Environment and Quality (POMREQ) in November. Our next development will be the conversion of biogas into compressed natural gas in cylinders,” Woo says.