The Use of Fly Ash and Bottom Ash to Reduce COD, TSS, and Color in Textile Industry Wastewater Effluent

The textile industry wastewater effluent contains some levels of COD, TSS, and color, it must be reprocessed as a tertiary treatment using the filtration method. The goal of this research was to examine the ability of fly ash and bottom ash as filtration media to reduce the pollutant / organic load of COD, TSS, and color in textile industry wastewater effluent. The slow sand filter method was used in this study, and the filter media was derived from coal combustion waste. The variation used in this study is a variation of filter media (fly ash and bottom ash), with fly ash diameters of 0.11 and 0.35 mm, bottom ash diameters of 0.85 - 1.50 mm, and media thickness of 1.50 - 2.00 mm (10 cm and 20 cm). The study’s findings demonstrated that using bottom ash and fly ash media in the filtration process with a slow sand filter system could maximize the efficiency of reducing COD, TSS, and color levels in textile industry wastewater effluent. In fly ash media, it can reduce COD, TSS, and Color by 90.58%, 81.87%, and 100%. Meanwhile, Bottom Ash filter media has an average COD, TSS, and Color reduction of 87.80%, 81.87%, and of 100%.


Introduction
The textile industry is a processing industry, which converts fiber into yarn or fabric [1].Textile products consist of fibers, yarns, fabrics, or clothing.The textile industry in Indonesia is one of the well-developed fields, which is expected to play a role in economic development and employment.One of Indonesia's well-developed industries, the textile and textile product sector are anticipated to contribute to both economic growth and job creation.Data from the Central Statistics Agency (BPS) shows that the production of the apparel industry experienced a significant growth of 15.29 percent.The output is waste with high levels of fatty oils, pH, and color, as well as high levels of BOD (Biochemical Oxygen Demand), COD (Chemical Oxygen Demand), TSS, Total Phenol, Cr, and Total Ammonia.The reddish-brown color itself is formed due to the dyeing process on the fabric, which can be synthetic or organic.In order to comply with Regulation of the Minister of Environment and Forestry of the Republic of Indonesia Number P.16/MENLHK/SETJEN/KUM.1/4/2019, the researchers in this study will perform further processing, specifically filtering.The amounts of COD, TSS, and color in the effluent from the textile sector can be reduced through filtration using a slow sand filter system.Slow sand filtration was the method of filtration employed in this study.A slow sand filter is a filter basin that use very fine-grained, high-quartz sand as the filtering medium.Raw water with moderate to low turbidity and moderate to high dissolved oxygen concentrations is better suited for treatment by slow sand filters [6].By using coal waste, specifically fly ash and bottom ash as the processing medium, the slow sand filter has a significant impact on eliminating organic matter content in the wastewater effluent despite operating at a speed of 20-50 times slower, or 0.1-0.4m/hour.Fly ash is a substance that emerges from a combustion furnace's chimney as an extremely fine dust, whereas bottom ash is a substance that emerges from coal combustion as coarse dust at the furnace's base.Both fly ash and bottom ash, which are by products of coal combustion, offer advantages in environmental treatment, one of which is as a filtration medium for wastewater treatment.Fly ash is composed of silica, iron oxide, aluminum oxide, potassium oxide, magnesium oxide, and sulphate, according to Santoso et al. (2004).The textile industry's heavy metal ions can be reduced using fly ash [18].Bottom ash can be a substitute for conventional industrial wastewater treatment methods because it is readily available in large quantities [9].Heavy metal ions and organic compounds can be absorbed very effectively by coal bottom ash [4].When employing fly ash and bottom ash as the filtering medium, the pollutant load can be reduced more effectively than when using activated carbon and activated zeolite, particularly when the TSS value is 32.5%, the COD value is 54.1%, the BOD value is 58.9%, and the heavy metal content is 80.8% Cr [9].According to Sinta Rismayani's research, reactive/disperse dyes decreased by 61% in 2007.TSS 16.9%, BOD 27.1%, COD 27.3%, and Cr 71.5% are decreased by activated carbon filtration, while active zeolite filters out TSS 19.4%, BOD 30.8%, and Cr 64.3%.According to the research described above, using bottom ash as a filtration medium has a higher percentage of pollutant reduction than using activated carbon and activated zeolite.This is because bottom ash has a higher percentage of pollutant reduction when compared to the circumstances of the characteristics of the wastewater effluent to be treated.The modifications used in this study include variations in the filtration media's thickness, filtration media's particle diameter, and filtration media itself.Fly ash with an effective size of 0.11 to 0.35 mm can be used to account for changes in the filtration particle size [2], Bottom ash with a range of 0.85 -2.00 mm produces good hydraulic conductivity and performance in the filtration process [12].Variations used in the filtration process to determine the percentage reduction in COD, TSS, and color levels in textile wastewater effluent.

Research Methods
This study is a laboratory-scale experiment to determine the efficiency of fly ash and bottom ash as filter media in reducing the content of COD, TSS, and color in textile industry wastewater effluent.

Artificial Textile Industrial Wastewater Effluent Manufacturing
Textile dyes Wenter with a total concentration of 70 ppm are used to make wastewater effluent from the textile industry.Textile dyes Wenter was basic material for artificial textile industry wastewater it contains of COD of 414 mg/L, TSS of 200 mg/L, and color of 717.5 Pt.Co

Tools and Materials
The materials used in this study were samples of artificial textile industry wastewater effluent, fly ash with a diameter of 0.11 -0.35 mm and bottom ash with a diameter of 0.85-2.00mm.Based on Figure 1 and Figure 2, the filter reactor was made by cylindrical glass with a glass thickness is 0.5 cm, a IOP Publishing doi:10.1088/1755-1315/1250/1/0120093 diameter is 4 cm, and a height is 40 cm.It was added with static head for water overflow is 20 cm, so the total height of reactor is 60 cm.Flowing artificial textile industry wastewater to a laboratory-scale filtration reactor with a down flow medium of fly ash and bottom ash.There is an adsorption mechanism in this filtration process that affects the decrease in COD, TSS, and Color values, particularly in the pore structure of fly ash and bottom ash media.The distribution of molecules that enter the carbon particles for adsorption is determined by the pore size.Because adsorption is the process of allowing molecules to enter pores, the organic compounds in wastewater will enter and be absorbed.

Characterization of Fly Ash and Bottom Ash
Before being used as filter media, fly ash and bottom ash will be analyzed using a scanning electron microscope (SEM).A scanning electron microscope is a device that produces an enlarged image and can reveal microscopic scale information about the size, shape, composition, crystallography, physical and chemical properties of a specimen.The basic operating principle of this SEM is that emission from the electron source creates a subtle focus on the energetic electron beam [13].
Figure 3. Fly Ash in SEM The Figure 3 above shows that fly ash has an irregular shape.Can be described by loose structure and rough surface.According to [14] based on the results of XRF monitoring it was explained that fly ash consists of O, Ca, Cl, Na, K, Si, S and other elements.Similar to coal ash in general, fly ash is the result of a high temperature combustion process, so the compounds contained in this fly ash are oxide compounds or silicon dioxide as the main component.In Figure 4, bottom ash depicts that the particles are significantly larger and angular, with many irregular fragments and only a small number of semi-spheres.It also shows some visible pores in the bottom ash microstructure.This observation is consistent with research conducted by [15] and [16] on the microstructure of bottom ash.Due to the composition of bottom ash which is high in silica and other metal oxides, it has a great possibility of removing dyes contained in wastewater.

Figure 5. COD Concentration Reduction Percentage Graph
Based on Figure 5, the percentage reduction in COD concentration at fly ash size 0.11 mm with a thickness of 10 cm is 92.27%, at fly ash size 0.35 mm with a thickness of 10 cm is 87.92%, at fly ash size 0.11 mm. the thickness of 20 cm is 91.30%, and the size of fly ash is 0.35 mm, the thickness of 20 cm is 90.82%.With average, it can reduce COD by 90.58 %.Based on Figure 6, the percentage reduction in TSS concentration at fly ash size 0.11 mm 10 cm thickness is 80.50%, at fly ash size 0.35 mm thickness 10 cm is 80.00%, at fly ash size 0.11 mm the thickness of 20 cm is 83.50%, and the size of fly ash is 0.35 mm, the thickness of 20 cm is 83.50%.The average decrease in TSS is 81.87%,

Figure 7. Color Concentration Reduction Percentage Graph
Based on Figure 7, the percentage reduction in COD concentration at fly ash size 0.11 mm thickness 10 cm is 100%, at fly ash size 0.35 mm thickness 10 cm is 100%, at fly ash size 0.11 mm thickness 20 cm. by 100%, and at the size of 0.35 mm fly ash thickness of 20 cm by 100%.So, the average is it can reduce color by 100%.
The thickness of the media has a significant impact on the filtration process in Figures 3 and 4 for the reduction concentrations of COD and TSS.This is because the thickness of the media affects the length of flow and the amount of filtering power [5].Contact between raw water containing COD, TSS, and color and fly ash media can improve the removal of pollutants in effluent.According to Sahu's (2002) research, using fly ash as an adsorbent for domestic wastewater treatment in rural areas is a very effective alternative medium for removing COD.Meanwhile, according to the graph above (figure 7), the concentration of color reduction is affected not by the thickness of the media, but by the adsorption mechanism in the media.Meanwhile, according to the graph above (figure 7), the concentration of color reduction is affected by the adsorption mechanism in the slow sand filter filtration process rather than the thickness of the media.Based on Figure 8, the percentage reduction in COD concentration at bottom ash size 0.85 -1.50 mm with a thickness of 10 cm is 93.48%, at bottom ash size 1.50 -2.00 mm with a thickness of 10 cm is 84.30.%, at bottom ash size 0.85 -1.50 mm with a thickness of 20 cm is 80.68%, and at bottom ash size 1.50 -2.00 mm with a thickness of 20 cm is 92.75 %.The average reduction of COD is 87.80 %,

Figure 9. COD Concentration Reduction Percentage Graph
Based on Figure 9, the percentage reduction in TSS concentration at bottom ash size 0.85 -1.50 mm with a thickness of 10 cm is 80.00 %, at bottom ash size 1.50 -2.00 mm with a thickness of 10 cm is 80.00 %, at bottom ash size 0.85 -1.50 mm with a thickness of 20 cm is 82.50 %, and at bottom ash size 1.50 -2.00 mm with a thickness of 20 cm is 85.00 %.The average TSS reduction is 81.87%.Based on Figure 10, the percentage reduction in Color concentration at bottom ash size 0.85 -1.50 mm with a thickness of 10 cm is 100,0 %, at bottom ash size 1.50 -2.00 mm with a thickness of 10 cm is 100,0 %, at bottom ash size 0.85 -1.50 mm with a thickness of 20 cm is 100,0 %, and at bottom ash size 1.50 -2.00 mm with a thickness of 20 cm is 100,0 %.Reducing color with an average percentage of 100%.
The variation in the diameter of the media greatly affects the filtration process as shown in Figures 8  and 9 for the concentration in the reduction of COD and TSS.The percentage of reduction increases with the diameter of the media used.Permeability increases with particle size.Bottom ash has a higher permeability than fly ash because it is dominated by sand particles.Permeability refers to a material layer's ability to allow fluids (such as water and air) to pass through existing and interconnected pore spaces [10].The Color (Figure 10) is influenced by the bottom ash media itself because it contains a high concentration of Si and Al.Furthermore, because the bottom ash is dry, it has many pores with a high level of porosity, resulting in an absorption capacity of 0.8-2.0%higher than wet bottom ash [3].

Conclusion
Based on the results of research that has been carried out on artificial textile industry wastewater effluent, the diameter of fly ash and bottom ash media can affect the reduction process of COD (Chemical Oxygen Demand), TSS (Total Suspended Solid) and the color contained.This slow sand filter reactor is very effective in reducing the content of COD, TSS, and color in textile industry wastewater effluent.Variations in particle diameter can affect the results of the filtration process, with fly ash and bottom ash as filter media capable of producing a high effectiveness of reducing organic matter (COD, TSS, and color), due to the presence of the main constituent of fly ash and bottom ash is Carbon, Silica, and Aluminum according to the results of the SEM-EDX (Scanning Electron Microscope-Energy Dispersive X-Ray) analysis.

Figure 4 .
Figure 4. Bottom Ash in SEM

Table 1 .
Artificial Textile Industry Wastewater Effluent Concentration