Palm Oil Mill Effluent as an Environmental Pollutant : Indonesia Palm Oil Industry

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http://dx.doi.org/10.33021/jenv.v8i1.3507 | 1

Palm Oil Mill Effluent as an Environmental Pollutant : Indonesia Palm Oil Industry

Dian Ari Saputri^1,*, Joseph Natanael¹, Najwa Sophia Maulida¹, Temmy Wikaringrum¹

1Environmental Engineering, Faculty of Engineering, President University, Cikarang, 17530, Indonesia

Manuscript History Received

20-Jan-2022 Revised 26-10-2022 Accepted 23-09-2022 Available online 14-04-2023

Abstract: Indonesia is one of the countries with the world's greatest processed palm oil reserves and production. The waste product of palm oil manufacturing is known as POME (palm oil mill effluent). POME can be used as a source of electricity and biogas, as well as a potential renewable energy source. Objectives: This research objective is to determine how can POME as a palm oil processing waste also having a good benefit that can use for human future.

Method and results: The strategy employed in this study was to collect scattered material from numerous online journals or papers as our data sources, which we then summarized to illustrate how Palm Oil Mill Effluent is a pollutant to the environment. Conclusion: With the increasing of energy demand in every region in Indonesia, especially remote parts and also regions that still have not experienced any energy development, it is very promising that the biogas produced from POME as one of the renewable energy sources that can reach all regions to remote areas of the country.

Keywords Palm Oil Mill Effluent;

wastewater;

treatment plant;

*Corresponding author: [email protected]

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1Introduction

Indonesia is one of the numerous countries that produce palm oil. There has been a huge increase in the area of oil palm plantations, according to data from plantation statistics for 2015-2019. The area of oil palm plantations in Indonesia increased fast from 11,260 million hectares in 2015 to 14,724 million hectares in 2019, implying that oil palm farms are found in practically every part of the country.

This huge growth provides a mixed bag of benefits and drawbacks. Palm oil is given as an example of a labor-intensive business with a high export value, with Rp.

304 trillion in total export value in 2019. This export is far more valuable than oil and gas exports. In Indonesia, oil palm farms directly employ roughly 4.2 million people and indirectly employ approximately 12 million people. Palm oil may also be utilized to provide energy security. Through the Biodiesel Mandatory initiative, processed palm oil products may be utilized to replace 2.3 million KL of fossil fuels.

Oil palm plantations, on the other hand, can have an impact on soil quality by reducing the soil's ability to hold rainwater, increasing the use of chemicals, introducing new pests, reducing the function of natural forests as infiltration and water producers, and, of course, increasing the waste generated by palm oil processing.

Palm oil processing waste is separated into two categories: liquid waste and solid trash. POME is the name given to this type of liquid waste (Palm Oil Mill Effluent). POME hasn't seen much use, although it has a lot of potential as an alternative energy source.

1.1 Palm Oil Definition

Palm oil is a plantation crop that produces a variety of excellent oils and is used as a raw material for a variety of products, including cooking oil, soap, margarine, biodiesel, cosmetics, and more. Palm oil's excellent oil has outstanding features, such as high coating power, oxidation resistance, and irritant resistance.

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Open pond technology, which consists of anaerobic, facultative, and aerobic ponds with an absolute retention duration of 90-120 days, is commonly used in POME management technology. This open pond method necessitates a considerable amount of land (5-7 ha), high maintenance expenses, and emits methane gas into the atmosphere.

POME management that relies solely on open ponds is now being viewed as inefficient and environmentally unfriendly. PKS's owners or management have begun to adapt by changing the current pond and incorporating additional management technology. Today, there are various innovative POME processing methods available, including membranes and electrocoagulation, to name a few.

Certain reasons and objectives drive the introduction or development of POME management technology.

1.2 POME in Indonesia

When considering the positive impact on environmental limits and pollution loads, as well as opportunities to produce renewable energy sources in terms of heat, energy, and fuel, Indonesia, as one of the world's largest palm oil producers, should prioritize technologies that can increase the economic value of waste. from argo-industrial plantations and agriculture's manufacturing method POME is a waste product from the palm oil production process. The composition of POME changes depending on how palm oil is processed. POME is made up of organic molecules that have a lot of free fatty acids, proteins, carbohydrates, nitrogen compounds, lipids, and minerals in them. POME is not considered a hazardous or toxic waste. POME is normally allowed to ferment or decay naturally in sewage ponds to create biogas.

In Indonesia, two biogas power plants are under construction, one of which is in the Pekanbaru region. The following are the goals of establishing a biogas plant:

1) to replace partial usage of shells and fibers as a burner and boiler fuel; 2) to

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generate power for companies, hence decreasing fuel prices; and 3) to generate electricity to sell to the grid PLN to raise revenue.

1.3 Palm Oil Management in Indonesia

Palm oil processing in Indonesia is assisted by management and monitoring by the government sector. Farmers, workers, and communities living near plantations must observe current regulations, such as those set forth in Minister of Agriculture Decree 357 of 2002 and modifications to Minister of Agriculture Regulation 98/2013 [25] governing Guidelines for Plantation Business Licensing, which include:

1. Cooperative-Investor Joint Venture Patterns; cooperatives control 65 percent of the stock, while investors/companies possess 35 percent.

2. Cooperative Investor Joint Venture Patterns; investors/companies control 80% of the stock, while cooperatives own at least 20% of the stock, which is steadily raised.

3. Applying to BTN (National Savings Bank) model, investors/companies create plantation or processes, which are then transferred on to interested cooperative members.

4. Other mutually advantageous, reinforcing, and necessary development patterns between smallholders and plantation businesses.

5. Plantation Business Cooperative Patterns; the Plantation Business Cooperative owns 100% of venture capital.

6. BOT (Build, Operate, and Transfer) Patterns: The investor or firm performs the construction and operation, which is subsequently completely transferred to the cooperative at a later date.

1.4 Characteristic of Palm Oil Mill Effluent

POME is typically collected from three main sources in the oil palm process:

clarifying wastewater, sterilizer condensate, and hydro-cyclone wastewater. Table 1 summarizes the general properties of each raw POME.

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http://dx.doi.org/10.33021/jenv.v8i1.3507 | 5 Table 1. General Characteristic of raw POME

Parameters Concentration Range Current Discharge Limit Chemical Oxygen Demand (COD) 15,000-100,000 -

Biochemical Oxygen Demand (BOD) 10,250-43,750 100 Total Suspended Solids (TSS) 5000-54,000 400

Oil and grease 130-18,000 50

Temperature 80-90 45

pH 3.4-5.2 5-9

All values, expect pH and temperature, were expressed in mg/L.

2 Method

The method used in this study is by collecting scattered information in several online journals or articles as our data sources and then we summarized to explain about Palm Oil Mill Effluent as an environmental pollutant.

3Results and Discussion

3.1 POME Management Technology

This POME management approach, which included anaerobic, facultative, and aerobic ponds, utilised open ponds with an absolute retention time of 90-120 days.

There's also a variety of POME therapy options, such as primary treatment, which focuses on physically removing floating chemicals. Secondary treatment, which includes biological methods for removing BOD, and tertiary processing, which involves removing organic chemicals and nutritional salts that were difficult to remove in the previous step. Because the open pool approach releases methane gas into the atmosphere, it necessitates a vast amount of land and has substantial maintenance expenses.

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However, the use of open ponds for POME management is currently considered inefficient and not environmentally friendly. PKS/POME owners and managers are starting to explore new technology developments and adapt by changing existing ponds and other management technologies. Membrane technology is one of the new POME technology developments currently on the market, and electrocoagulation technology is the latest technological development. The multiple aims of the new technologies have led to the introduction of advanced POME management technology development.

3.2 Current and Modern Utilization

The methane produced by POME may be captured and used as an electrical generator with great efficiency. In addition to being able to produce methane gas as energy, some palm oil mills in Indonesia that process their POME using landfill gas technology have been notified that their POME is also capable of creating energy from hydrogen gas (H2).

Electrocoagulation is a technology that POME can use to create hydrogen gas.

This electrocoagulation technique works on the basis of electrolysis, which contains two electrodes: a cathode and an anode. This cathode electrode creates a hydrogen bubble that serves as a negative pole and a site for reduction reactions, while the anode electrode serves as a positive pole and a place for oxidation reactions.

POME started to focus on the usage of biofuels as a result of many research.

The oil content of POME can be separated using a substance that is based on the difference in solubility in two different liquids that are mutually insoluble in biodiesel as the basic material. When POME is dumped in a hot wok, the oil that is still connected to the POME can be separated from the water, mud, and other contents, allowing biodiesel to be used directly.

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http://dx.doi.org/10.33021/jenv.v8i1.3507 | 7 3.3 POME Treatment Process

3.3.1 Ponding system or Land Application

For wastewater treatment, pond systems are used by up to 85% of palm oil processing plants. Cost effectiveness, minimal maintenance costs, electricity efficiency, system dependability, and simple design are just a few of the reasons.

The pool system, on the other hand, is deemed inefficient in various ways, including the requirement for longer hydraulic retention periods (HRT) and vast pool areas.

The design of POME treatment via pond system is the effluent stabilization pond, which flows from the acid pond to the final polishing pond. This method gives a general HRT of 100-120 per day before being deactivated. The oil trap pond sends crude POME to the acidification pond. After that, the raw POME will be kept for around 6 days in an acidification pool. After being planted for 6 days and kept for around 7 days, POME is fed straight into a cooling pond via a cooling tower. The POME pH will be balanced and the POME temperature in the cooling pool will be reduced before moving on to the next stage. When POME is cooled, its high initial temperature promotes thermal and anaerobic digestion, mostly by hydrolysis and acidogenesis. The most effective approach for anaerobic breakdown of excessively electrified wastewater has been discovered to be anaerobic treatment pools.

Complex polymers such as carbohydrates, proteins, and lipids are broken down into their fundamental monomers during the hydrolysis process. The production of sugar, amino acids, and fatty acids, for example, has been assisted by thermo-tolerant bacteria. During the acidogenesis process, carbon-containing monomers are fermented into unstable fatty acids (VFA) like acetic acid (HAc), propionic acid (HPr), butyric acid (HBu), valeric acid (HVa) with trace-non VFA, and lactic acid.

Acetogenesis converted the long chain VFA (HPr, HBu, and HVa) created hydrogen and carbon dioxide from acidogenesis (CO2). Hydrogen and CO2 were then used by hydrogenotropic methanogens, while acetoclastic methanogens used

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HAc and CO2 to produce methane gas. Methane gas is the ultimate value-added product in the biogas production process. Anaerobically handled POME become alkaline and exist as blackish brown due to the decomposition of the longest chain fatty acids (LCFA) and volatile fatty acids due to partial breakdown of the lignin into phenolic (VFA). In the anaerobic treatment stages, four ponding collections were used, with a total HRT of 54–60 days. Before being discharged into the facultative pools, the anaerobic POME is treated for around 20 days in a three-tiered system of aeration ponds with floating aerators.

The facultative pool is divided into three series. The facultative pond is essential for reducing organic material in waste before it is disposed of in rivers, as required by the 1974 Environmental Quality Act (EQA), which governs the disposal of crude palm oil processing waste. After passing through the facultative pool, POME enters the sedimentation tank first, which takes around 2 days. An aerobic technique is used in the final pond, which involves suspended microbial classification. Many researchers assess the success of a completed pond system in terms of meeting waste disposal needs.

The anaerobic pond method need to provide remarkable overall quality in treating POME due to the elimination of high concentrations of organic features in POME. However, this treatment process makes achieving a perfect staining turn difficult. The open-pond approach can reduce COD (100–1725 mg/L), BOD (100–

610 mg/L), and ammonia nitrogen (100–200 mg/L) levels to the desired levels. The open pool strategy, on the other hand, has the problem of requiring a big space.

Due to the production of methane gas, it is difficult to locate the suitable huge environment. In addition, there is a biogas tank that can also be opened or closed in accordance with the pond system. The biogas tank has minimal running expenses, a short HRT time, and only takes up a little amount of space. The digester, on the other hand, might create dangerous biogas gas. Despite the fact that installing a CH4 collecting system provides a variety of advantages, such as lowering greenhouse gas emissions, producing renewable energy, and enhancing

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quality of the soil and FFB production, the technique is too pricey for the next characteristics of the project.

3.3.2 Biological Treatment

Pond methods are quite well methods for huge POME processing technology, but they are costly and need vast areas (30–45 hectares) and lengthy HRT (100–160 days). Because of the widespread usage of pond methods, there is a strong desire for reduced prices and more efficient material utilization on a large scale. Thus, several recent research have focused on the treatment of POME utilizing biological approaches using bacteria, fungus, yeast, microalgae, and different microbial cultures.

Because of the higher amount of natural COD, BOD, TSS, and choices efficiency, and also the presence of oils and fats, anaerobic devices are chosen.

Because of their ecologically favorable construction, anaerobic systems are regarded distinctive and important. Anaerobic systems can produce methane gas, which can be used to generate energy. The organic matter in anaerobic wastewater is not totally stable, according to Chan et al., and additional treatment is necessary to eliminate the presence of certain ions in the effluent. To achieve the discharge criteria, anaerobic equipment was paired with aerobic POME decomposition.

Another green technique that has gained prominence in recent decades is phytoremediation. Phytoremediation is a cost-effective solution that also addresses aesthetic and sustainability problems. The most critical element to consider before beginning any remediation process is plant selection. Excessive nutrient absorption as well as heavy metal absorption in wastewater are important characteristics. Typha latifolia was used in POME phytoremediation and was shown to be effective in lowering COD concentrations by up to 97.18 %. Using a 45 L volume of POME, Vetiveria zizanioides was found to decrease COD and BOD levels

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by up to 94 % and 90 %, respectively, in just two weeks. Phytoremediation is a simple, low-cost, widely available, and ecologically benign method of soil cleanup.

Many researchers have expressed interest in using microbial fuel cells (MFC) to treat POME. In comparison to the previous ponding system, MFC could now be accomplished at room temperature with low substrate concentration levels. An organic-rich wastewater was used to generate electrical energy with the help of microorganisms, which is regarded as a cost-effective and sustainable energy source. Even though POME can be converted into electricity using a single chamber of MFC, the COD and BOD removal efficiencies remain unsatisfactory. The substrate type, treatment parameters, reactor design, and operational costs all contributed to the observation of low COD and BOD elimination.

Both of the crude and watery POME in the MFC twin chambers was treated with polyacrylonitrile carbon press and Nafion 117 membranes. Crude POME demonstrated a weaker COD removal effectiveness (45%) than watery POME after 15 days of culture (70 percent ). The power generation rose as when the beginning COD value is increased, implying that MFC device using raw POME operated faster than the dilute one. A 2 MFC mixture mixed with stationary bacterial aeration cleaning is used to modify the conventional approach of biological treatment treatment systems. With such a volume of 2.36 L, this cutting-edge device reduces COD - more to 96.50 percent in just 10 days of operation. MFC has various limitations, such as capital expenses and technical elements of electron transfer performance, while being a basic and easy-to-use device. a serious flaw

3.4 Palm Oil Mill Effluent as Biogas

Waste treatment methods include physical, chemical, and biological methods.

Coagulation, flocculation, sedimentation, and flotation are the processes used to treat chemical waste. Chemical processes are frequently less effective because the cost of chemicals is quite high and a large volume of sludge is produced. While aerobic and anaerobic processes can be used to treat biological waste.

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Traditionally, palm oil mill effluent is treated biologically using ponds, which means that liquid waste is processed in aerobic and anaerobic ponds using microbes as BOD reformers and neutralizing the acidity of the wastewater.

The process that occurs in the anaerobic pond in the traditional system is substituted into the digester tank for palm oil mill wastewater treatment utilizing an anaerobic digester. The anaerobic pond is replaced by the digester tank, which is aided by the employment of mesophilic and thermophilic microorganisms (Naibaho, 1996). Methanogenic bacteria alter the substrate and create methane gas in both of these bacteria.

Anaerobic fermentation is the process of upgrading organic matter in a digester tank (closed reactor) at a temperature of 35-55 degrees by a group of facultative and obligate anaerobic bacteria. The anaerobic metabolism of cellulose is more challenging than the anaerobic metabolism of other organic molecules like as carbohydrates, proteins, and lipids because it includes several complicated processes. The hydrolysis process, the acidogenesis process, the acetogenesis process, and the methanogenesis process are all steps of biodegradation. The hydrolysis process is a decomposition of complex biomass into simple glucose that uses microorganism-produced enzymes as a catalyst. As a result, the biomass becomes soluble in water and takes on a simpler form. The acidogenesis process involves the reshuffling of monomers and oligomers to produce acetic acid, CO2, short chain fatty acids, and alcohol. The acidogenesis process, also known as the non-methanogenesis phase, generates acetic acid, CO2, and H2. Meanwhile, methanogenesis is the process by which compounds are converted into methane gas by methanogenic bacteria. Methanobacillus omelianskii is a well-known methanogenic bacteria.

Methanogenic bioconversion is a biological process that is heavily influenced by environmental factors, both biotic and abiotic. Microbes and active bodies are examples of biotic factors. The type and concentration of inoculum factors are critical in the process of revamping and producing biogas. According to the findings

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of Mahajoeno et al. (2008), the inoculum of LKLM II-20 % (w/v) with 15 L of substrate produced the most biogas compared to other concentrations, with a total of 121 liters produced. While abiotic factors include agitation, temperature, acidity level (pH), substrate content, water content, C/N ratio, and P content in the substrate, as well as the presence of toxic materials, biotic factors include agitation, temperature, acidity level (pH), substrate content, water content, C/N ratio, and P content in the substrate, as well as the presence of toxic materials (Mahajoeno, et al, 2008). Temperature, pH, and toxic compounds are the main controlling factors for biogas production among the abiotic factors mentioned above.

Increasing the temperature can also increase the rate of biogas production.

Microbes require the temperature of the liquid according to the type of microbes being developed. Based on the nature of the adaptation of bacteria to temperature can be divided into 3 (three) parts (Naibaho, 1996), namely:

1. Phsycrophiles, which are bacteria that can live actively at low temperatures of 10^oC, these bacteria are found in sub-tropical areas.

2. Mesophiles, which are bacteria that live at a temperature of 10-50^oC and are the most common types of bacteria found in the tropics.

3. Thermophil, namely bacteria that are heat resistant at a temperature of 50-80^oC. These bacteria are often found in oil mines originating from the bowels of the earth.

The use of thermophil bacteria can speed up waste recycling. High temperatures can cause chemical changes, which methanogenic bacteria will use to produce methane gas, allowing biogas to be produced. A temperature increase of 40 degrees Celsius can generate 68.5 liters of biogas (Mahajoeno, et al, 2008).

The fermentation time factor also influences the yield of biogas production.

This is because the anaerobic overhaul is divided into four (four) stages. Each process necessitates a sufficient amount of time. The effect of fermentation time

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on biogas production yields different results. The longer the fermentation process, the more biogas is produced.

According to the research, kinetic parameters, particularly the maximum microbial growth rate constant and determining the minimum biomass residence time, are important in bioreactor design. The semi-saturated constant (Ks) 1.06 g/L, maximum specific growth rate (m) 0.187/day, biomass rollover (Y) 0.395 gVSS/gCOD, mortality rate constant microorganisms (Kd) 0.027/day, and maximum substrate utilization constant (k) 0.474/day were the optimum anaerobic biodegradation parameters of Palm Oil Mill effluent.

The biogas potential of 600-700 kg of PMKS liquid waste is approximately 20 m3, and each m3 of methane gas can be converted into energy of 4,700-6,000 kcal or 20-24 MJ (Isroi, 2008). A PMKS with a capacity of 30 tons of FFB/hour can generate biogas with an energy output of 237 KwH. (Naibaho, 1996).

4Conclusions

Indonesia is one of the world's major producers and exporters of palm oil. Palm oil is produced from harvested palm fruit bunches that are processed immediately at the facility for oil extraction. Several steps of crude palm oil extraction from fresh fruit bunches need a lot of water, and nearly half of the water used in this extraction stage ends up in the liquid waste of palm oil manufacturing, known as POME. POME is a waste water that, due to its high COD and BOD concentrations, can contaminate the environment if discarded directly.

Many treatment approaches have been explored to handle POME, including biophysical biological mechanisms, bioadsorbents, membranes, and coagulants, but there is no one solution that can be employed on a commercial scale. It is expected that the adoption of low-cost biomaterials, fast treatment periods, and adaptable and clean technology would pave the way for effective POME therapy.

To be used to some extent, most processing methods must have ecologically

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beneficial features. Biological approaches give more benefits than chemical methods.

With the increasing of energy demand in every region, especially remote parts and also regions that still have not experienced any energy development, it is very promising that the biogas produced from POME as one of the renewable energy sources that can reach all regions to remote areas of the country. Therefore, it is highly expected by every palm oil mill, community, and local government to continue supporting renewing energy sources from palm oil waste so that it can be processed more environmentally friendly and produce things that are beneficial to the surrounding environment.

5Aknowledgement

All of the Author would like to thanks to Mrs. Ir. Temmy Wikaningrum, M.Si as the author’s Lecturer and also as the author’s Advisor for all the guidance during working this paper. And also all of the authors would like to say thanks to all of the author's friends in ENV 2020 that always give support to each other.

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