Water quality enhancement through vertical and horizontal roughing filtration (case study: drilling well at Mojorejo Village, Batu City, Indonesia)

Roughing filtration is crucial in wastewater treatment by efficiently separating small solid particles without chemicals. Conducting a pilot project in Mojorejo Village aimed to evaluate the viability of using horizontal-flow roughing filtration for drinking water treatment. The filter consists of three distinct sections separated by perforated baffles. Each compartment is filled with local sand and gravel arranged in a specific decreasing size sequence. The filter demonstrates satisfactory performance in removing turbidity and total suspended solids. Gravel was selected as the control medium due to its widespread use in roughing filters. The filter also effectively removes iron, manganese, and color. The study results suggest that horizontal-flow roughing filtration could be a cost-effective and efficient pre-treatment process, particularly when surface water is utilized as the water source. It is particularly suitable for small-scale communities and scenarios where water is free from significant pollutants. This system can serve as a comprehensive treatment system, allowing the treated water to be distributed for various uses.


Introduction
Safe and clean drinking water access is an essential human need for both health and sustainable development.As we know, drinking water is a basic human need.Sometimes, users are provided with inadequately treated or completely untreated water [1], [2].For instance, around 51% of 593 rural municipalities in Quebec, Canada, use only chlorination, and up to 26% supply untreated water [3].Similarly, in rural China, only 50-70% of drinking water samples meet standards, while approximately 40% remain untreated [4], [5].In Indonesia, inadequate drinking water quality cases have also been identified.The decline in source water quality, coupled with the lack of funds, technical expertise, and management resources, presents significant challenges for rural drinking water treatment, necessitating an urgently needed treatment technology that is economical, effective, and easy to manage.
The location where humans or communities live will determine how the community gets drinking water.In general, people who live in remote areas do not receive drinking water services from Municipal Water Corporation take water from nearby areas to meet their drinking water needs.The water source can be a river, well, or rainwater.However, especially in rural areas, not all groundwater sources are 1311 (2024) 012021 IOP Publishing doi:10.1088/1755-1315/1311/1/012021 2 suitable for drinking because existing water sources have an odor, color, unpleasant taste or contain several compounds that are dangerous to health issues due to insufficient treatment [6] and deterioration of source water quality [7], financial problem, technical, and management support deficits commonly result in under quality drinking water in rural areas, affecting the overall drinking water quality.
Roughing filtration, a chemical-free technique known for its impressive ability to retain solids, simple management, and cost-effective operation, has been successfully deployed in rural regions for years.Previous research has highlighted the effectiveness and reliability of roughing filtration in eliminating suspended solids, turbidity, and coliform bacteria [5], [8], [9], [10].Roughing filters (RFs) are often employed as pre-treatment steps before slow sand filtration [11] and can even replace coagulation-sedimentation processes [12], [13].Typically, RFs are filled with medium-sized materials ranging from 4 to 30 mm and are operated with low hydraulic loads varying between 0.3 to 1.5 m h -1 [13], [14].Roughing filters are mainly used to segregate water from fine solids only partially or not retained by settling basins or sedimentation tanks.Besides solid separation, roughing filters also improve bacteriological water quality and, to a lesser extent, modify certain water quality parameters, such as watercolor and dissolved organic matter levels [15].Regarding technical labor requirements, daily operation, maintenance expenses, treatment efficiency, and effectiveness, roughing filtration offers a straightforward, efficient, and cost-efficient pre-treatment technology for treating drinking water or wastewater compared to conventional methods like chemical coagulation [11].
The water source in the Dusun Ngandat comes from drilling wells and is used as daily drinking water.Based on interviews with residents, when supplied to households, the water from these wells has a yellowish color and a slightly musty odor.If left in a bathtub, it leaves yellow to brown stains, rendering it not fully usable by the residents.A prototype of a filtration device is employed to purify water from the drilled wells in Dusun Ngandat, which supplies clean water for the residents.The well water's quality exceeding the standard limits is filtered using vertical and horizontal filtering mechanisms.The filtration process employs the Roughing Filter principle.A roughing filter, categorized as a physical filter, involves the absorption of materials or substances by porous media [14].The separation process of nonsettleable solids that cause discolored or cloudy water, both suspended and emulsified, in the water, the initial stage of water purification, is known as the coagulation process.In several studies, this coagulation process can remove organic and inorganic substances, color, bacteria, algae, and plankton from the water.
This research explores the capabilities of a combination of Vertical and Horizontal Roughing Filtration using a filter assembly of activated carbon, zeolite, volcanic sand, and pumice stone to enhance the quality of water sourced from boreholes.This enhancement is marked by reduced turbidity, decreased Total Dissolved Solids (TDS), increased Oxidation Reduction Potential (ORP), and the quest for the optimal composition of these composites.This study provides an initial step towards developing a simple drinking water supply technology made from local natural materials.This technology combines several water purification procedures (coagulation, flocculation, sedimentation, ion exchange, adsorption, and filtration) into a single process to improve the quality of water obtained from boreholes.

Research location
The research was conducted at a drilling well in Dusun Ngandat, Mojorejo Village, Batu, Indonesia.Mojorejo Village is situated to the east of the Tourism City of Batu, at 7°52"-7°53" south latitude and 112°32"-112°34" east longitude.The village experiences an annual rainfall of 2,000-3,000 mm with an average air temperature ranging from 21°C to 24°C.This makes Village Mojorejo a cool and humid village.The rainy months in Village Mojorejo typically amount to five months each year.Village Mojorejo is located in a highland area characterized by black soil color and clayey or loamy soil texture, with a soil depth of 0.5 meters, rendering the land fertile.It is one of the villages within the Junrejo Subdistrict of Tourism City Batu.The approximate land area of Village Mojorejo is 175 hectares.Geographically, the village is situated at 600-650 meters above sea level, classifying it as a highland area.The research location is indicated in Figure 1.

Filter material
Activated carbon has been widely used in water treatment as a filter and an adsorbent.It is reported that activated carbon can remove odors, unpleasant tastes, and coloration primarily caused by organic matter and residual organisms, and it can also eliminate bacteria and viruses.Some literature reports suggest that activated carbon may not remove all free metal ions in water.However, preliminary research results indicate that activated carbon has significant absorption capacity for ions such as Al, Cr, As, Se, Ag, Pb, Cu, Mn, and Fe, especially at pH 7. Activated carbon is made from coconut shells in granular form and is made at temperatures ranging from 450°C to 800°C.
Zeolite has also been extensively used in water purification as an adsorbent and ion exchanger.It is reported that zeolite can effectively adsorb compounds in water, such as ammonia, amines, some organic compounds including pesticides, and toxic chemical compounds like Se, Sr, Pb, Cd, Ag, and heavy metals.

Equipment and Model Arrangement
This study selected a combination of vertical and horizontal flow roughing filters as the pre-treatment filter consisting of four and six compartments, respectively.The construction of the filtration model utilizes glass material with dimensions of 38x30x12 cm for the vertical filter and 80x40x40 cm for the horizontal filter.The model of the flow roughing filter was also completed with polyvinyl chloride (PVC) pipes with a 250-litre tank as a water source for the roughing filter model.The two filters are interconnected using 0.5-inch PVC pipes with a support frame for the filters that employ perforated iron angle pipes.Measure water parameters such as pH, turbidity, TDS, Conductivity, Oxidation-Reduction Potential (ORP), and dissolved oxygen (DO).The model is running using the Horiba U-50 series water quality checker.The source water for a sample to be analyzed was obtained from a drilling well at Dusun Ngandat, Batu, near the model's placement.The arrangement of the vertical and horizontal flow roughing filter is shown in Figure 2. Materials used for filtration are readily available from construction supply stores and chemical material shops.The materials in the compartment consisted of coconut fiber as media 1, volcanic sand as media 2, zeolite as media 3, activated carbon as media 4, and pumice stone as media 5.The selection of materials used as roughing filters considered their function in the filtration process.Ijuk functions to filter fine impurities [2].Sand can trap larger particles with its closely packed grains [4].Activated carbon absorbs odor, heavy metals, color, and chlorine and enhances the taste of water [8].Zeolite can absorb various heavy metal ions and organic compounds from water [10].Pumice stone is an absorptive material for substances like manganese oxide, iron oxide, and amorphous silica, reducing Fe content and turbidity in well water [11].
The percentage increasing or decreasing of pH, turbidity, TDS, Conductivity, Oxidation-Reduction Potential (ORP), and dissolved oxygen (DO) was used to measure performance.The Horiba U-50 series water quality checker measured turbidity in nephelometric turbidity units (NTU), TDS and DO in mg/l, Conductivity in µS/cm, and ORP in mv.Measurement was done every 15 minutes for one hour.The measuring points were the inlets and outlets of the vertical and horizontal flow roughing filter units.

Source of water sampling
The analyzed water samples consist of well water and filtered water.The well water is collected in a tank with a capacity of 250 liters and then flowed at a rate of 0.3 liters/second to the vertical filter, which comprises four layers of filtering materials.After the vertically filtered water is collected in a reservoir, it is then directed to the horizontal filter, which consists of 6 chambers, including two chambers for collecting water and four chambers for filtering materials.The sampling process involves two stages: in-situ measurements and laboratory measurements.Parameters analyzed in this research include temperature, pH, ORP, Conductivity, turbidity, DO, TDS, Fe, Hardness, and Cl.The analysis results will be compared with the water quality standard No. 22 of 2021 concerning the implementation of environmental protection and management issued by the government of the Republic of Indonesia.Table 1 shows the initial parameter of water obtained from the groundwater drilling well.

Results and Discussion
The filtration process is divided into two models: Model 1 and Model 2. The distinction between each model lies in the composition of their respective filtering media.Model 1 is employed for the vertical filter, with the sequence of filtering media being coconut fiber, activated carbon, zeolite, and pumice stone.For the horizontal filter, the media sequence consists of a chamber for collecting dirty water, volcanic sand, activated carbon, zeolite, and pumice stone, and a chamber for collecting clean water.
The first sampling was conducted after 5 minutes of water flowing through the outlet channel, and subsequent samples were taken at 15-minute intervals up to 65 minutes.The measurement results of the physical parameters using Model 1 filtration show several changes from the initial conditions.The ORP parameter experienced an increase, while temperature, pH, Conductivity (DHL), turbidity, and Total Dissolved Solids (TDS) underwent a decrease.The DO parameter tended to remain stable.
The increase in ORP values is due to water storage in both the initial and final reservoirs of the Horizontal-flow Roughing Filter (HRF) that has passed through the Vertical-flow Roughing Filter (VRF).Meanwhile, the decrease in temperature, pH, Conductivity (TDS), turbidity, and Total Dissolved Solids (TDS) results from the influence of filter materials such as zeolite and activated carbon, reducing these parameters.
For instance, the decrease in pH occurs due to pressure in the water, and the water temperature causes the evaporation of CO2 gas, which normalizes the pH.Meanwhile, Dissolved Oxygen (DO) remains constant due to aeration occurring in the Vertical-flow Roughing Filter (VRF), which continues in the Horizontal-flow Roughing Filter (HRF).The result of parameters from model 1 is shown in Table 1.The results of model 1 show that physical parameters, including color, odor, and taste, organoleptically tend to change.The color is now clear, with turbidity reaching 15.9 (NTU) and no odor.Initially, the water before filtration had an iron rust smell, but after filtration, there is no longer any odor.As for taste, there has been a reduction in the iron rust taste in the filtered result.This is due to the influence of filtration materials, including zeolite and activated carbon.The zeolite used can absorb various chemicals, ions, and organic compounds from water, as well as an electric charge that can attract and bind these substances, including heavy metals, ammonia, phosphates, and organic compounds that can contaminate water.The activated carbon can absorb odors, iron (Fe) content, and color in well water, resulting in changes in the well water's color, odor, and taste after filtration.
Model 2 is utilized for the vertical filter where the usage of pumice stone is changed with volcanic sand.The sequence of filtering media in Model 2 becomes coconut fiber, activated carbon, zeolite, and volcanic sand.Otherwise, for the horizontal filter, the media sequence consists of a chamber for 1311 (2024) 012021 IOP Publishing doi:10.1088/1755-1315/1311/1/0120216 collecting dirty water, volcanic sand, activated carbon, zeolite, activated carbon, and a chamber for collecting clean water.Table 3 shows the water parameter result from Model 2.  Based on the analysis results, it is evident that the well water stored in the tank has a higher temperature.This is due to the tank's exposure to direct sunlight, with temperatures ranging from around 30.45 to 32.7°C.In Model 1, the temperature value at the fifth minute experiences a decrease from 32.7°C to 27.04°C.This significant temperature change is attributed to the prolonged exposure of the water in the tank to direct sunlight.From the 5 th to the 65th minute in scaled model running, the water temperature remains relatively stable, fluctuating within ±3°C, with values ranging from 27.04°C to 29.77°C.A temperature decrease from the 0th to the 5th minute also occurs in the Model 2 test.However, the water temperature remains relatively stable from the 5 th to the 65 th minute, around

Figure 4. Analysis results of pH content
Based on the analysis results, the pH values of the well water and the filtered water at each time interval fall within the range of water quality standards, which is 6 to 9. The results of filtering the well water indicate that the pH of the water ranges from 7.31 to 7.93.The water's pH tends to be neutral to slightly alkaline, indicating that salts formed are derived from alkaline ions.

Figure 5. Analysis results of ORP content
Water quality standards do not require oxidation-reduction potential (ORP).However, ORP provides information about oxidation and reduction reactions in the water.The analysis results indicate a significant increase from initial to filtration conditions.Factors contributing to redox reactions in filtration include aeration processes in the vertical filter, which can introduce oxygen to form oxide compounds.In the horizontal filter, filtering media can lead to oxidation-reduction reactions.Electrical conductivity is a parameter influenced by the presence of free ions in water.The higher the concentration of free ions, the higher the Conductivity value (DHL).Based on the analysis results, the existing well water has a significantly high DHL value, ranging from 3250 to 3300 µS/cm.These values fall within the high category compared to typical well water DHL values.The analysis results indicate that the filtration process can reduce the DHL value, albeit not significantly.The limited significance of the filtration results is attributed to the natural materials used, which have a limited ability to bind the free ions in the water.

Figure 7. Analysis results of turbidity content
Based on the analysis results, the turbidity parameter experiences a significant decrease from its initial conditions.The well water, with turbidity values of 56.3 to 61.5 NTU, can be reduced to 27.8 to 12.3 NTU after passing through the filtration device.The media, such as coconut fiber (ijuk), sand, and zeolite, with grain sizes ranging from 0.6 to 0.25 mm, can effectively filter suspended particles in the water.Enhancing the water's clarity, activated carbon possesses the capacity to absorb even very small particles.

Figure 8. Analysis Results of Dissolved Oxygen (DO) Content
The dissolved oxygen content in the well water falls below the water quality standard, ranging from 4.61 to 4.7 mg/L.The aeration process conducted in the vertical filter is expected to enhance the oxygen content in the water.The dissolved oxygen value in the water after passing through the filtration device experiences an increase, even surpassing the water quality standard.However, the overall increase is not significant.Model 2's highest increase occurred at t-50 until it reached the DO quality standard.

Figure 9. Analysis results of TDS content
The dissolved solids present in the well water are very high, reaching levels of 2080 to 2110 mg/L, indicating a substantial amount of dissolved salts.Filtration of the well water can reduce and stabilize the TDS values to around 2000 mg/L.TDS value is high in groundwater sources and can be caused by Water Quality Standard organic, inorganic, sedimentation, and other dissolved solid waste materials [16].The pH of the air also influences the high TDS.Metal ions dissolve in water at low pH, so TDS levels become high [17].
From the effectiveness calculations of filtration models 1 and 2, it is observed that model 1 is more effective in improving the quality of well water compared to model 2. The largest increase is seen in the ORP parameter, with effectiveness reaching 19300%, which shows that aeration and filtration are important in encouraging redox reactions in well water.The turbidity parameter decreased effectiveness by 70%, showing that the natural materials used are very good as filter media.Conductivity Parameters (DHL) and TDS experienced a less significant decrease in effectiveness, amounting to 6%.This was caused by the high concentration of free ions and dissolved salts that had not been filtered and precipitated completely.The highest effectiveness in the DO parameter occurred in Model 2, with an effectiveness of 4%.The results of measuring physical parameters with Model 2 show several changes from initial conditions, such as a decrease in temperature of 12% and an increase in pH of 11.3%.Some parameters are following water quality standards, but there are still some that require improvement.This filter can be easily realized because the media material used comes from nature and is easy for the public to obtain.

Conclusion
This research uses two filtration models, namely Model 1 and Model 2, which differ in the composition of the filtration media.Model 1 on the vertical filter uses a media composition of coconut fiber, activated carbon, zeolite, and pumice, while the horizontal filter uses a media composition of sand, active carbon, zeolite, and pumice.In Model 2, the vertical media filter uses coconut fiber, activated carbon, zeolite, and sand.The media uses sand, activated carbon, zeolite, and activated carbon for the horizontal filter.The research results show that Model 1 is more effective in improving the quality of water wells compared to Model 2. There are significant changes during the filtration process based on the measurements of physical parameters, such as temperature, pH, ORP, DHL, turbidity, DO, and TDS.Most of these parameters experience an increase or decrease due to the influence of the filtration media used.
Model 1 effectively reduces certain parameters, especially ORP, turbidity, and DHL.The effectiveness of Model 2 is also visible, especially in the DO parameter.The analysis results are compared with the water quality standards stipulated in Indonesian Government Regulation No. 22 of 2021 concerning implementing Environmental Protection and Management.Some parameters are following water quality standards, but there are still some that require improvement.
Future studies are needed on the roughing filter system, including the combination of Vertical-flow Roughing Filter (VRF) and Horizontal-flow Roughing Filter (HRF).This study should encompass the filter apparatus's design, the filter media selection, and the media's arrangement to achieve more effective results that align with existing water quality standards.For more effective results, it is 1311 (2024) 012021 IOP Publishing doi:10.1088/1755-1315/1311/1/01202111 recommended to add materials that can bind free ions to water so that it can reduce the conductivity and TDS value.

Figure 2 .
Figure 2. Arrangement of the filtration model

Figure 3 .
Figure 3. Analysis Results of Temperature Content . The well water temperature's variation from the ambient temperature remains within the ±3°C range, which aligns with the established quality standards.

Table 1 .
The initial parameter of water

Table 2 .
Data from the filtration of Model 1

Table 3 .
Data from the filtration of Model 2 Sampling times were conducted as in Model 1, at 15-minute intervals during 65 minutes duration.Temperature and turbidity exhibit a downward trend, while pH and ORP parameters tend to rise.Conductivity (DHL), DO, and TDS exhibit stable values.The analysis results were compared to the quality standards outlined in the Indonesian Government Regulation No. 22 of 2021 concerning implementing Environmental Protection and Management.The analysis of each parameter is as follows:

Table 4 .
Data on effectiveness analysis