Bagasse and bamboo charcoal comparison: as adsorbents for waste water to comply with Indonesian environmental quality standards

Bagasse; which is sugar cane waste; and bamboo charcoal usually are disposed of right away. However, if both are further being processed, they would have had economic values; which one of them is as adsorbent for waste formation water from petroleum production operation, to comply with Indonesian environmental quality standard for waste water disposal. The aims and the objectives of this research are to obtain the adsorption ability of bagasse and bamboo charcoal, and the adsorption ratios of the two materials. First, it is necessary to activate carbon which presents in bagasse and bamboo charcoal waste, by grinding the materials. Then, there are five concentrations for each of the adsorbent in the waste water being used; 0.5 gr/cc, 1 gr/cc, 1.5 gr/cc, 2 gr/cc, and 2.5 gr/cc. This study indicates that the adsorbent from bagasse and bamboo charcoal does able to reduce the pH, salinity and TDS values according to the standard qualities set by the government. Bagasse adsorbent with concentrations of 1.5 gr/cc, 2 gr/cc, and 2.5 gr/cc would able to reduce pH value of waste water to meet government’s standard quality, while bamboo charcoal adsorbent with concentrations of 2 gr/cc and 2.5 gr/cc would able to reduce the pH value of standard value. The higher the concentration of bagasse and bamboo charcoal the lower the values of pH, salinity, and TDS. Comparing bagasse and bamboo charcoal; bagasse performance is better than bamboo charcoal.


Introduction
Oil and gas production activities produce formation water waste, if special treatment is not carried out according to quality standards it would damage the environment, therefore it is necessary for adsorbents to reduce the hazard content during oil and gas production, in this case by using adsorbent.The values of pH, salinity, and TDS in the waste water should meet the government standard quality, for the waste to be disposed into the river.The adsorption that would certainly require more handling cost, which is inexpensive.This research is to evaluate adsorption experiment on formation water what from oil production operation, so that the produce water could be flown into the river safely, without damaging the environment.The adsorbent material is coming from waste of other industry and easily to be obtained, that is not only to reduce the values of pH, salinity, and TDS, but also to utilize the waste from other industry to become valuable.
The production of sugar cane in Indonesia reaches 2.42 million tons in 2021, which means that there is a lot of waste of bagasse for sugar production, that would certainly become waste and pollute the environment as well.Bagasse of sugar cane would be utilized as adsorbent.Furthermore, based on the "2019 Forestry Production Statistics" published by the Central Bureau of Statistics (BPS); bamboo is the most produced commodity; namely 17.1 billion sticks; for non-timber forest products.Therefore, there is certainly also a large amount of waste produced by the bamboo itself, and this research would use adsorbent materials derived bamboo waste.

Characteristics of Formation Water
Formation water obtained from the oil and gas industry production operation is certainly waste product of the operation.To dispose the waste water product to environment or river, the parameters contained in the formation water have to meet values set by the government according to regulation of the Ministry for the Environment number 19, year 2010 concerning waste water quality standards for oil and gas and geothermal businesses and/or activities and also for exploration activities.There are parameters which is characteristics of formation water waste; such as COD, fatty oil, dissolved sulfides, ammonia, total phenol, temperature, pH, and TDS to be considered.Therefore, for the formation of produced waste water to be disposed of into the environment, The waste water has to meet Ministerial Regulation.Table 1 describes the details of the characteristics of formation water according to the Ministry.

Adsorption
Adsorption is the process by which a substance (adsorbate) accumulates on the surface of another substance (adsorbent).This process usually occurs in several phases such as gas-liquid, liquid-liquid, solid-gas, liquid-solid (Cecen & Ozgur, 2011).The adsorption process will occur if there is an attractive force between the solute and the adsorbent surface.If the attractive force between the adsorbate molecules and the active side of the adsorbent surface is stronger than the attractive force between the adsorbate molecules, then there will be a transfer of the adsorbate mass from the mobile phase to the adsorbent surface.

Adsorbent
Adsorbent is a type of solid substance that can adsorb particles in the adsorption process.There are several adsorbents that are widely used, one of which is activated carbon and activated charcoal.In the adsorption process occurs, the adsorbate is adsorbed by the adsorbent.If the speed of its use is increased or decreased, it forms a new equilibrium state.The adsorbent process is carried out with a good adsorbent with conditions such as: x Has high absorption x Not soluble in adsorbate x Harmless x The price is inexpensive and easy to get x Does not experience chemical reactions x Does not produce residue in the form of smelly gas In this study, there are 2 types of adsorbent materials used as adsorbents, namely bagasse and bamboo charcoal.The selection of the two materials is due to the characteristics that are suitable for the requirements as adsorbents which have been described previously.

Methods
The experiment was using sample from actual waste product of petroleum production operation with certain parameters.The parameters are 31.5 mg/l salinity, pH 11, TDS 5048 mg/l, and temperature 32.2 O C. Initially, the carbon contained in the bagasse and bamboo charcoal needs to be activated by grinding the two materials.The bagasse and bamboo charcoal; as adsorbent; were then mixed with waste water sample with 5 (five) different concentrations of 0.5 gr/cc, 1 gr/cc, 1.5 gr/cc, 2 gr/cc, and 2.5 gr/cc.The pH, salinity, and TDS of the sample formation waste water sample containing bagasse and bamboo charcoal adsorbent were measured.It was observed the concentration of each adsorbent at which environmental quality standards were reached.

Result and discussion
Each adsorbent of bagasse and bamboo charcoal adsorbents were mixed with waste water sample, which causing the waste water mixture parameters would change.Table 2 below is the summary of the change in waste water parameters after being added with bagasse and bamboo charcoal adsorbents.The adsorbent is mixed with waste formation water, causing the acidity of the waste water change according to absorbent concentration pour into the waste water, as shown in Figure 1.The shows that after the increase of bagasse and bamboo charcoal concentrations, decreased the acidity pH after adding 1 gr/cc concentration of adsorbents.The higher the adsorbent concentration given to the waste water, the higher the decrease of pH occurrence.According to ministry of environmental regulation no.19 year 2010, the acidity pH waste formation water quality standards has to be from 6 to 9 to be disposed to the environment.At bagasse and bamboo charcoal absorbents concentration at 2.5 gr/cc, the waste water acidity lays in the range of waste water standard quality; which has acidity pH of 8.Moreover, bagasse concentration of 1.5 gr/cc in the waste water, able to decrease the waste water acidity to 9 pH, which meets the waste water quality.At 1.5 gr/cc of bamboo charcoal mixture, the waste water acidity pH is still 10.In the case of lowering the acidity pH, bagasse is favourable as compared to bamboo charcoal.Furthermore, the effect of addition adsorbents in the waste water toward total dissolved solids TDS contained in the waste water, could be seen in Figure 2.

Figure 2. The Effect of Adsorbent Concentration on TDS
As per Environmental Ministry Regulation no.19 year 2010, the maximum waste water quality standards of total dissolved solids TDS has to be 4000 ppm.Bagasse adsorbent at a concentration of 2 gr/cc is only able to reduce the TDS levels to below 4000 ppm, which is 3843 ppm.The adsorbent from bamboo charcoal with a concentration of 1 gr/cc is able to reduce the TDS value to below 4000 ppm, namely 3914 TDS.However, at a concentration of 2.5 gr/cc, bagasse performs much better than bamboo charcoal.Bagasse is able to reduce the TDS value more optimally.Which is 3561 ppm, while at 2.5 gr/cc of bamboo charcoal, the TDS becomes 3590 ppm.The higher the concentration of the adsorbents, the lower the TDS level of formation water.
From the point of view of waste water salinity, both adsorbents are able to reduce the salinity of waste brackish water sample.The initial value of waste water salinity at 31.5 ppm, could be reduces to below 29 ppm of standard waste water quality.The salinity continues to decline with additional adsorbent pour into the waste water sample.
Figure 3 is the effect of adsorbent concentration on salinity.Bagasse adsorbent at a concentration of 1 gr/cc is able to reduce the salinity to 27.5 ppm, which is value below 29 ppm; while the bamboo charcoal adsorbent is able to reduce the salinity at higher concentration of 1.5 gr/cc, which is 28 ppm.The use of bagasse adsorbent at 2.5 gr/cc concentration would reduce salinity more optimal than of bamboo charcoal at the 2.5 gr/cc, that is 22 ppm for bagasse, and 24.5 ppm for bamboo charcoal.The salinity is directly proportional to the TDS, thus, the same as TDS reduction, the use of bagasse and bamboo charcoal adsorbents would reduce the salinity value below the set waste water quality standard.

Figure 3. The Effect of Adsorbent Concentration on Salinity
It is concluded that the two adsorbents are able to reduce the pH, TDS, and salinity below the set of waste water quality standards.Moreover, it is also to be understand the adsorption power of these two adsorbents.
From the five values of absorbents concentrations, there are percentages of volume from the initial waste water volume pour in into the mixture, of each five concentrations and the two adsorbents is depicted in Table 3.At a concentration of 0.5 gr/cc bagasse is better in absorbing the waste water than bamboo charcoal; where the bagasse adsorbs 16% volume of waste, while bamboo charcoal absorbs only 12% of waste ware.At the same time, at concentrations of 1 gr/cc, 1.5 gr/cc, 2 gr/cc, and 2.5 gr/cc, bagasse performs much greater absorbing waste water as compared to bamboo charcoal.The higher the concentration of the adsorbent, the greater the adsorption obtained.At a concentration of 2.5 gr/cc, the bagasse adsorbent is capable to dissolve 53% volume of waste water, while bamboo charcoal with a concentration of 2.5 grams is capable to absorb only 47% of waste water, which is slightly lower than that of bagasse.
Another factor that could affect waste water adsorption is contact time.In this study, it was tested contact time for each of the adsorbent.The contact time measured in this is at 2.5 gr/cc concentration of bagasse and bamboo charcoal.Table 4 is the effect of contact time on the volume of waste water.In this study the contact time used was from 15 minutes and 75 minutes, with 15 minutes increment.The volume absorbed by bagasse and bamboo charcoal are directly proportional to the contact time; the longer the contact time the higher the adsorption occurs.In 15 minutes of contact time, bagasse adsorbed 47% of the initial waste water volume, while bamboo charcoal was only 40% of initial waste water volume.And at 75 minutes of contact time, using bagasse adsorbent was able to adsorb 60%, while bamboo charcoal is only 55%.The performance of absorbing waster on bagasse is better that of the bamboo charcoal.

Conclusion
Several conclusions could be drawn from this research: 1. Bagasse and bamboo charcoal adsorbents are able to reduce formation water acidity to meet environmental quality standard, which is between pH 6 to 9. Bagasse at a concentration of 1.5 gr/cc is able to lower the pH to 9 from 11, while bamboo charcoal to lower pH to 9, it needs a concentration of 2 gr/cc.2. Bagasse and bamboo charcoal adsorbents are able to reduce formation water TDS to meet environmental quality standard, which is below 4000 ppm.Bagasse concentration of 2 gr/cc is able to reduce TDS to 3843 ppm from 5048 ppm, while bamboo charcoal concentrated at 1 gr/cc to lower to 3914 ppm.At higher concentration of 2.5 gr/cc, bagasse performance is better than bamboo charcoal; to 3560 ppm for bagasse and 3590 ppm for bamboo charcoal.3. Bagasse and bamboo charcoal adsorbents are able to reduce formation water salinity to meet environmental standard, which is below 29 ppm.Waste water with bagasse absorbent at 1 gr/cc is able to reduce salinity to 27.4 ppm, while bamboo charcoal at 1.5 gr/cc to reduce to 27.9 ppm. 4. Bagasse absorbs more water as compared to Bamboo Charcoal.At 2.5 gr/cc of adsorbents, bagasse absorbs 53% water, while bamboo charcoal absorbs 47% water.5. Bagasse absorbs more water at certain contact time as compared to Bamboo Charcoal.At 75 minutes of contact time, bagasse absorbs 60% water, while bamboo charcoal absorbs 55% water.6. Bagasse performs better as adsorbent, as compared to Bamboo Charcoal.

Figure 1 .
Figure 1.The Effect of Adsorbent Concentration on Acidity pH

Table 1 .
Wastewater Quality Standards for Oil and Gas Exploration and Production activities

Table 2 .
Summary of Experimemt Result

Table 3 .
Percentage of Absorption in Each Adsorbent