Coffee Shop Liquid Waste Treatment System Using Portable Waste Water Treatment Plant (WWTP)

Coffee shops produce waste that is included in the category of domestic waste in a fairly large amount. Therefore, it is necessary to carry out domestic wastewater management. One solution is the design of an integrated portable WWTP that can treat waste from coffee shop business activities. The advantages of using WWTP are that it is simple and does not require large amounts of land. The processing of this WWTP consists of filtration and precipitation. The wastewater to be filtered will be separated from the solids, after which it will be continued with stratified filtration using activated carbon. In the study, variations in flow rate were carried out to determine processing efficiency, namely variations in tap openings of 30 o , 45 o , and 90 o with water flow rate of 200, 360, and 570 mL/s. The result of research, the portable Wastewater Treatment Plant with activated carbon filtration designed has been able to treat coffee shop liquid waste. The variation of flow rate in the processing of coffee shop liquid waste affects the processing results where the smaller the flow rate, the greater the efficiency reduction. The optimum flow rate variation in this study is 200 mL/s with a COD removal efficiency of 48.5%, TSS 72.8%, Coliform 66.6%, TDS 62.5%, and pH 6.2. The suggestion that can be given is the addition of a biological treatment system to optimize the performance of Portable WWTP.


PENDAHULUAN
Pontianak is known as the city of a million coffee shops.Based on data, the number of coffee shops and cafes in Pontianak is almost 800 business places that operate up to 24 hours a day and can increase 30% of Regional Original Revenue and absorb a lot of labor.However, it causes problems in the form of liquid waste from coffee shop activity (Abrori, 2021).So far, coffee shops do not have an adequate waste treatment system where liquid waste is directly disposed of in the ditch.Coffee shop liquid waste is dominated by organic waste derived from food washing residues, detergents (Phosphorus) and decomposition of protein materials that increase ammonia (Nitrogen) content which can damage the environment if above the threshold.However, in the treatment of coffee shop waste, there are problems that arise, including land requirements and high costs for the construction of installations with complicated operating systems.
The solution to this problem is to build a portable WWTP (Waste Water Treatment Plant).The use of portable WWTP has technical and economic advantages, such as lower investment costs of up to 30% of conventional WWTP, simple operation and maintenance, and does not require large areas of land (Nafi'ah, 2015) can save the use of clean water (Neles et al., 2020).The design of a portable WWTP is integrated with a washing basin in order to treat the waste of coffee shop business activities while recycling wastewater so that it is expected to be reused for bath wash toilet .
This WWTP treatment can be used for liquid waste which consists of filtration and settling.The wastewater to be filtered will be separated from the solids after which it will continue with multilevel filtration using activated carbon and ultrafiltration membranes.The adsorption properties of activated carbon are selective and depends on the surface area and base or pore volume.A significant amount of activated carbon can be absorbed.,which is 25-100% so that activated carbon is often used to reduce organic contaminants.In addition, activated carbon is also effective for reducing inorganic contaminants such as radon, mercury, and other toxic metals, because it has a large particle size and surface Pratiwi et al. (2016) According to research from Pratiwi et al. (2016) activated carbon can reduce COD and pH levels in laundry liquid waste where COD levels can be reduced by up to 42% and a decrease in pH is 7.50 mg/L.This portable WWTP with activated carbon filter and ultrafiltration membrane will be designed with a design shaped like a sink so that the tool can save space.From this research, the efficiency of the portable WWTP tool will also be studied with variations in tap openings.Variations in tap openings are carried out to see their effect on the results of processing coffee shop liquid waste.The tap opening study will affect the wastewater flow rate per unit time that comes out to the filtration tank.Therefore, a study of coffee wastewater treatment using a portable WWTP with variations in tap openings was carried out to obtain optimum results.

METHODOLOGY 1. Portable WWTP Designer
The design of the Portable WWTP that will be used is an integrated processing between the washing basin and the processing device with multilevel filtration.Figure 1 below is a flowchart of the Portable WWTP design.

Operational Testing of Portable WWTP
The collection of this liquid waste was carried out on weekend days where based on the results of a simple survey, the number of sales and visitors increased sharply compared to other days so that samples in the form of coffee shop liquid waste were generated in abundance.Sampling of this liquid waste is carried out at 14.00 WIB which is washing time so that the waste that can be taken for samples is quite a lot.The initial characteristics of the waste before processing are shown in Table 3.The stages of waste treatment using this portable WWTP begin by flowing the collected waste into the first filter where the first reservoir has a honeycomb-shaped filter which is used to filter out large particles such as the remaining coffee grounds that are still in the waste.Then the liquid waste is flowed into a second reservoir which has a microfilter to filter out fine particles that escape in the first filter.Then the liquid waste will be pumped into the tank to enter the adsorption column.The adsorption process is carried out with a residence time of 20 minutes in the column.Inside the tank is an adsorption column consisting of 12 mesh large activated carbon and 20 mesh small activated carbon then the outer/last layer is adsorbed with a microfilter cloth.This activated carbon also needs to be activated for high absorption and aims to enlarge the pores of the carbon (Heriyani and Mugisidi, 2016).

2.1.Effect of Flow Rate on Chemical Oxygen Demand (COD) Levels
In testing COD levels, several variations of flow rate were carried out so that it was found that the increase in flow rate proved that the decrease in COD was influenced by flow rate.

Figure 5. COD Reduction Based on Flow Rate
Based on Figure 5.The processing results at 30° discharge opening efficiency is 48.5%, 45° efficiency is 15.1%, and 60° efficiency is 2.4%.In Figure 5.1 below, it can be seen that the decrease in COD levels is quite significant.The decrease in COD levels is due to the adsorption process by activated carbon.During the interaction process, activated carbon particles intersect with the compounds to be absorbed so that during the contact time, the adsorption power increases.Activated carbon has an active -OH group that provides hydrophilic properties of the adsorbent surface so that the molecules of organic compounds in polar COD will interact strongly with the adsorbent.Adsorption with activated carbon is a type of physical adsorption involving pores and van der waals forces (Arif et al., 2015).
From the results of research using variations in flow rate, it was found that the greater the flow rate, the efficiency of reducing COD levels decreased.This is because the higher the flow velocity will cause large particles to escape.These particles will close the pore holes so that they will accelerate clogging (Maryani et al., 2014).But the fine particles escaped due to the high flow rate which caused the COD to remain high.So that the optimum flow rate for reducing COD levels is 200 mL/s with a decrease in COD levels of 48.5%.

Effect of Flow Rate on Total Suspended Solid (TSS) Levels
In this study, the results of the research obtained each decrease based on the flow rate.At a flow rate of 200 mL/s there was a decrease in TSS levels of up to 72.8%.This decrease is due to the adsorption process on the filtering media due to the difference in charge on the surface of the media with the surrounding suspended and colloidal particles.The adsorption process can effectively reduce suspended substances in effluent wastewater with a flow rate of 200 mL/s.The length of time wastewater spends in contact with activated carbon increases with decreasing flow rate, so that the absorption process of suspended substances in waste can take place optimally and suspended substances can enter the pores of the adsorbent and reduce TSS levels in coffee shop liquid waste (Matilda et al., 2016).
Based on Figure 6, it can be seen that the most effective reduction in this study is at a flow rate of 200 mL/s with a final TSS value of 102 mg/L.The greater the flow rate used, the smaller the efficiency of reducing TSS levels.This happens because at a large flow rate, the possibility of flock escape will be even greater and in the adsorption process.Figure 6.TSS Reduction Based on Flow Rate Activated carbon also cannot absorb optimally.A low flow rate results in a high TSS reduction so that the water will be clearer because the contact time of activated carbon in wastewater is long, which will increase the absorption capacity of activated carbon to the maximum (Matilda et al., 2016).

2.3.Efect of Flow Rate on Total Dissolved Solid (TDS) Levels
After adsorption, there is a different decrease based on the flow rate.The more the flow rate of wastewater flows, the efficiency of reducing TDS also decreases.
Figure 7. TDS Decrease Based on Flow Rate This is because the higher the flow velocity, it will cause large particles to escape where the wastewater has residual detergent particles so that the activated carbon absorbs these large particles (Matilda et al., 2016).As for the flow rate variation of 200 mL/s, 360 mL/s, and 570 mL/s, it resulted in a decrease of 65.2%, 53.4%, and 40.9%, respectively.This decrease can be seen in Figure 7. Based on Figure 7, in this study there was a significant decrease in the flow rate of 200 mL/s, 360 mL/s, and 570 mL/s with an initial TDS value of 219 mg/L.The optimum result in this wastewater treatment was 76.6 mg/L at a flow rate of 200 mL/s.This states that the interaction between adsorbate and adsorbent is optimal.The high speed does not give good results because it can cause desorption and damage the pore structure of the adsorbent.

Effect of Flow Rate on Ammonia Levels
For this coffee shop liquid waste, it is known that the ammonia content of the initial waste is 1.82 mg/L.In adsorption with a flow rate variation of 200 mL/s, 360 mL/s, and 570 mL/s, the final ammonia content is 94.5%, 8.2%, and 27.6%, respectively.As can be seen in the Table 4.
According to Solikhah (2018), the decrease in ammonia occurs due to adsorption by activated carbon due to the potential difference between adsorbate molecules and the active surface in the adsorbent pores.The force causes adsorbate molecules to diffusely adsorb into the pores of the adsorbent and bond for a certain time.However, in the treatment results with this portable WWTP there is an increase in ammonia levels after treatment.Based on the processing data, the portable WWTP with filtration system has not been able to treat ammonia pollutants, this is because the activated carbon adsorption is not able to adsorb ammonia optimally.Ammonia treatment can be done by adding biological treatment units, both aerobic (Wahyuni et al., 2014) and anaerobic (Al Kholif et al., 2022).

Effect of Flow Rate on Total Coliform Levels
For this study, the initial total coliform wastewater level was obtained at 30 mg/L.After adsorption is carried out on this liquid waste with variations in flow rate, the results of the decrease can be obtained, namely at a flow rate of 200 mL / s of 66.6%, 360 mL / s of 100%, and 570 mL / s of 66.6%.Can be seen decrease in coliform in Figure 8.According to Rahmayanti et al. (2019) the decrease in coliform is due to interactions in the pores of activated carbon which are able to bind or absorb bacterial cells in liquid waste, so that the number of bacteria in this liquid waste is reduced.This activated carbon is able to adsorb bacterial cells with a surface that is selective in adsorbing specific microorganisms.This is due to the physical adsorption process by activated carbon media where bacteria are weakly bound to the adsorbent surface.
Based on Figure 8, the flow rate has a very significant effect on the decrease in coliform, which in the flow rate of 360 mL/s the decrease is higher than the flow rate of 200 mL/s and 570 mL/s the decrease is 66.6%.The efficiency of reducing coliform bacteria is more influenced by the residence time of water for 20 minutes.In theory, a lower flow rate will result in a higher decrease in coliform.This is because the low flow rate has a longer flowing time and greater filtering power.Contact between wastewater containing bacteria and activated carbon is longer so that the removal of coliform bacteria is better.with low speed can increase the time of removal of pathogenic bacteria, so that pathogenic bacteria can be retained on activated carbon (Maryani et al., 2014).In this coliform parameter, the optimum flow rate variation based on the reduction efficiency is 360 mL/s.According to P.68 / Menlhk / Setjen / Kum.1 / 8/2016 the maximum level of total coliform domestic wastewater quality standards is 3000 numbers/100 mL, so that the reduction in coliform levels is feasible enough to meet domestic wastewater quality standards.

Effect of Flow Rate on pH
In this study, the initial wastewater pH was obtained at 4.7.After adsorption is carried out on liquid waste, the results of the pH increase are obtained at a flow rate of 200 mL/s of 5.9, 360 mL/s of 5.9, and 570 mL/s of 6.2.This pH increase can be seen in Table 5.

Figure 1 .
Figure 1.Flowchart of Portable WWTP Construction Design

FigureFigure 3 .Filter
Figure 2. Technical drawing of Portable WWTP SinkTable 1. Sink Design Specifications Nature Specifications Conditions T=25-30 o C; P = 1 atm Shape/Material Open upright square with flat/aluminum base Volume 22.5 Liters Cylinder Dimensions -Base length -Tub height -Tub width 1.45 m 0.25 m 0.50 Support Components -Iron filter 1"

Figure 8 .
Figure 8. Coliform Reduction Based on Flow Rate

Table 3 .
Test Results of Waste Characteristics Before Treatment

Table 4 .
Ammonia Concentration Table

Table 5 .
Increase in pH Based on Flow Rate