Tuesday September 18, 2012
By MENG YEW CHOONG
Improved waste treatment system helps mills avoid river pollution.
SABAH plans to adopt more stringent anti-pollution standards for wastewater generated by the palm oil industry, and mills are rising up to the challenge. Some palm oil mills have put up more intensive effluent treatment systems in order to comply with rules on cleaner discharges.
This is good news f or the people and wildlife living along the state’s longest river, the Kinabatangan.
In 2006, Sabah had instructed mills operating along the Kinabatangan to introduce more levels of treatment for their palm oil mill effluent (POME) b efore the final discharge into the river. Even when treated, POME still imposes a demand on the environment as it still contains a significant amount of organic matter.
Mi crobes in water take in dissolved oxygen as t hey digest organic matter. This demand for oxygen is called biochemical oxygen demand (BOD) and is usually measured in milligrammes per litre (mg/l). BOD is widely used as an indication of the organic quality or the degree of organic pollution of water – a higher BOD means poorer quality, and the inverse holds tr ue as well.
Generally, the microbia l population increases in proportion to the amount of fo od available. In such instances, the microbial action will consume dissolved oxygen faster than atmospheric oxygen can dissolve in the water. When that happens, fish and oth er aquatic life might die because of depleted oxygen.
Raw or untreated POME is character ised by high BOD, often in the range of 25, 000mg/l or higher.
To protect the environ ment, the Government has limited the BOD of POME discharges into watercourses (ranging from lakes to rivers) to 100mg/l since 1984. Discharges onto land (as fertilis er or for irrigation) has been capped at 5,000m g/l since 1979, though the Department of Environment (DOE) can impose more stringent requirement s upon mills located in ecolo gically sensi tive areas. I n Sabah, the BOD limit for new mills that discharge o nto the land for irrigation has been gradually lowered over the years: 5,000mg/l in 1978, 1,000 mg/l in 1980, 500 mg/l in 1981, 250 mg/l in 1982, 100 mg/l in 1984, and 20 mg/l in 2006.
There are 124 palm oil m ills in Sabah, of which 35 are loca ted in the Kinabatangan basin. The river basin deserv es special attention because it hosts an incredible range of wildlife and flora, making it one of the world’s megabiodiversity hotspots and Sabah’s prized ecotourism asset.
Following a directive fr om the Sabah cabinet, a taskforce comprising the Malaysian Palm Oil Board (MPOB), DOE and the Malaysian Palm Oil Association (MPOA ) has been formed this year to move th e ind ustry towards higher standards.
The mills in the Kinabatangan area collectively discharge more than six million cubic metres of effluent annually . It must be noted, however, that they are not the only ones contributing to the organic loading of the river. A DOE survey presented i n 2010 found that mills contributed only 0. 7% to the total BOD loading of the river. Non-point sources (dispersed source s which cannot be specifically identified) were the main contributors. For example, production forests (forests currently being logged) contributed 165,113kg/ day of BOD, or 73 times more th an the mills.
Seen from another perspective, the contribution of non-point sources towards BOD levels in the Kinabatangan is 124 times more than the mills. However, when viewed from the p oint sources angle al one, the mills contributed 55% of the BOD level.
Raw mill effluent is a mixture of w ater, oil and suspended solids (20,000 to 40,000mg/l) as well as a moderate level of ammoniacal nitrogen (35mg/l), which is a measure for the amount of a mmonia in rivers. The most common way of treating POME is the open ponding system which is workabl e when land is cheap and abundant. This system is backed by secondary and tertiary treatment systems to ensure that the final discharge meets existing requirements.
Tertiary tre atment systems include a combination of extended aeration before the sludge goes through membrane ultra-filtration. However, with the good price of crude palm oil in the past few ye ars, plantation land is no longer abundant or cheap.
Sabah wants mills to constantly look for ways to improve the quality of their discharges. The industry, while conceding that proper effluent management is importan t, is asking for a more lenient 50mg/l , which most players in the state can meet on a regular basis. It says difficulties arise when the bar is raised to 20mg/l.
“Many palm oil mills have problems meeting the 20mg/l limit,” said Datuk Mamat Salleh, chief executive of MPOA during a re ce nt field trip to Sabah.
The barrier is not so much technical as financ ial in nature, as complying with the 20mg/l limit means having to invest in “effluent polishing plants”. The skill and knowledge of the plant operator is also important in ensuring that a plant can meet the discharge requirement consistently. For example, even though a treatment plant may be designed to reduce the BOD load to 20mg/l, it does not necessarily follow that the discharge will be always below the limit.
“It is not easy and it takes one year to stabilise the plant. You have to gain indepth knowledge of the plant as you are essentially operating a biological system, with microbes doing the work. You have to keep the microbial population healthy by giving it enough food, keeping the mix at the right temperature, ensuring that n ot too much POME enters the system (thus overloading it), as well as keep rainwater out of the mix,” said an official of Genting Plantations Bhd.
One industry observer puts the 50mg/l figure as a compromise between DOE (a Federal department) and the Sabah Environment Protection Department. On its part as the regulator of the industry, MPOB is trying to be middleman to help both parties arrive at a workable solution.
“The industry recognises the importance of POME management , but feels that 50mg /l limit is more practical and r easonable,” said MPOB director-general Datuk Dr Choo Yuen May.
Effluent with BOD lower than 50mg/l is generally considered acceptable t o be released to watercourses, provided no water intake point is located downstream. Ju st for comparison, the national sewerage company, Indah Water Konsortium, also has to comply with the 50mg/l limit if the effluent discharge point is after a water treatment intake point. If the discharge is above an intake point, then the 20mg/l limit applies.
MPOB is currently evaluating the capability of existing mills to meet the 20 mg/l requirement, even as Sabah DOE keeps an eagle eye on a few mills that have occasionally not met the 50mg/l limit.
Genting Plantations’ Trushidup Palm Oil Mill near Sandakan consistently averages a BOD level of 20mg/l for its effluent which is discharged onto its plantation land for irrigation. It is also working towards a zero-discharge plant for one of its mills in Sabah, and is constantly refining its process to ensure that all its mills can meet the 20mg/l limit at all times.
“We had to perform a gap analysis by looking at where are we now, where we would like to be, and how we can get there. It is about continuous improvement and refinement of the process,” said the Genting Plantation official.
The Malaysian palm oil industry is always improving its practices to minimise impact on ecology and the environment. With Sabah continuing to encourage the industry to adopt ever higher standards, it is hoped that palm oil mills will no longer be accused, rightly or wrongly, as th e source of pollution in the Kinabatangan river basin in the years to come.