Application of Combined Phytoremediation Greywater Treatment in A Single House

SUBMITTED 28 July 2020 REVISED 12 September 2020 ACCEPTED 28 september 2020 ABSTRACT By 2018, 22% of households in Indonesia did not have a proper sanitation facility, thus potentially discharge their wastewater directly to the surface water, which pollutes the water and environment around it. Furthermore, the quality of water resources is declining nationwide due to pollution; therefore, it affects the cost of water treatment. To reduce the pollution load, it is necessary to find the most effective treatment. Greywater treatment using plants (phytotechnology) combined with solar ultraviolet (UV) system is one of the breakthroughs that meet the criteria of low cost, simple in operation and maintenance, and energy saving. This study aims to study the performance of the coupled greywater treatment and investigate its possibility to be implemented in the actual condition in a single house used. This paper presents the combined treatment of physical treatment and phytoremediation with the addition of solar disinfection treatment. The selected treatment units for this study are a collection and sedimentation chamber, filter, phytoremediation, and solar disinfection chamber. Flowrate was measured by measuring the difference of water level over time. Influent and effluent quality were measured in the inlet of sedimentation chamber and outlet of disinfection chamber. From study, it is known that the efficiency removal of organic up to 92% while solids content was still high (removal efficiency of 49%). This system was also able to remove the ammonia well (57% removal) and reduce the pathogenic bacteria by 88%. The treated water quality (effluent) has met the requirements of the Provincial Regulation of Central Java No. 5 of 2012 and Class 3 standard (water for cultivation of plants and fisheries) of Indonesian Government Regulation No. 82 of 2001. However, it does not yet meet the standard for toilet flushing water according to the standard from U.K, U.S.A and Australia. This result showed this treatment system were not able to treat water that can replace the indoor water use. Therefore, applying an advanced treatment of greywater, such as Submerged Membrane Bioreactor, might be applied to maximize the intake of treated greywater for indoor and outdoor uses.


INTRODUCTION
A report presented in 2018 showed 78% of households in Indonesia have a sanitation facility and the contamination of the surface water was likely associated with domestic wastewater (Kementerian Perencanaan Pembangunan Nasional Republik Indonesia, 2019). This consists of greywater which makes 50-70% of the total water consumed and blackwater and despite the high volume of greywater, it only contributes 30% of the organic fraction and 9-20% of the nutrients and several million bacteria and this makes it a good source for reusable water (Fountoulakis et al., 2016;Bute et al., 2017). The water demand in a household includes those required for drinking, kitchen, bath, flushing of the toilet, and garden irrigation and those associated with toilet flushing and garden irrigation have been reported to be responsible for 20-30% and 10%-20% respectively of the water consumption in the household (Oh et al., 2018;Prathapar et al., 2005). A source with good quality is preferred for drinking, kitchen, and bathwater while reusable water is allowed for the flushing of toilet and garden irrigation (Dolnicar, Hurlimann, and Grün, 2010). This means it is possible to use the greywater from every household to support the water demand for toilet flushing and garden irrigation and this is expected to reduce the demand for fresh water supplies as well as the amount of wastewater discharged into the environment (Marleni and Raspati, 2020). Therefore, greywater recycling represents a plausible system-level approach to achieve greater water sustainability and resiliency (Ma et al., 2015).
Greywater contains lesser contaminants compared to blackwater but has the ability to cause a hazard when used untreated, therefore, there is a need for its treatment before utilization. Several studies have, however, applied or reviewed the treatment of greywater to select the best method based on the usage while some focused on the physical, chemical, and biological treatment and the combination of physical and biological treatment. A study showed the single application of physical treatment processes only is sufficient for greywater with deficient organic strength at <280 mg/L (Li, Wichmann, and Otterpohl, 2009). Moreover, a submerged membrane bioreactor was applied in a single house and proven effective in filtering the fine particulate, removing the pathogens, and reducing the organics and nutrients (Fountoulakis et al., 2016) but its operation and maintenance are not easy due to the need to change some of its spare parts once in a while. Biological treatment systems also often have some problems such as the formation of foam and inefficient sludge settling which usually leads to the deterioration of their performance (Bradley et al., 2002). Therefore, only a few households have the ability to apply this treatment because it is expensive and require extra effort to keep the membrane running smoothly. Biological treatment depends on the ratio of BOD/COD and since greywater mostly has a higher rate of these characteristics with nutrient efficiency, it serves as a limitation to the use of this method (Jefferson et al., 2000).
Chemical treatment such as the addition of aluminum sulfate has also been applied to treat the colloidal matters in the greywater (Li, Wichmann and Otterpohl, 2009) but it requires analysis to determine the appropriate dosage. This is considered to be costly based on the expenses of chemicals and the space for storage. Moreover, it is discovered not to be suitable for garden irrigation due to the need for water with fewer chemicals in ensuring plant growth.
The on-site household greywater treatment and reuse system required in most cases is usually expected to have a robust daily variation of greywater load, high pollutant removal efficiency, simple operation and maintenance, and easily monitored by the inhabitants. Phytoremediation method is a natural process which involves the application of plants on greywater treatment and has been confirmed to be cost-effective, easy to operate and maintain, stable, and robust (Arden and Ma, 2018;Chandekar and Godboley, 2015;Laaffat, Ouazzani, and Mandi, 2015;Bute et al., 2017). Moreover, contaminants are absorbed by macrophytes and stored in the macrophytes shoot and leaves during the phytoremediation process (Bute et al., 2017).
Phytoremediation has the ability to remove organic and nutrients but its ability to remove or deactivate pathogens considered to be important to human health is still being questioned (Arden and Ma, 2018;Oh et al., 2018). Therefore, it is necessary to combine the method with another disinfection treatment which is expected to be selected using certain criteria such as ease of operation and maintenance, cost-effectiveness, and robustness (Marleni, Ermawati, and Firdaus, 2020). The disinfection with natural U.V. from sunlight is considered a clean treatment with high pathogen removal ability, safe for plants, and low cost (Pansonato et al., 2011). Meanwhile, the use of phytoremediation treatment as a stand-alone unit process does not have the ability to reliably meet microbiological effluent standards (Arden and Ma, 2018;Li, Wichmann and Otterpohl, 2009). Therefore, it needs to be coupled with another effective and efficient pathogen treatment but there is currently a lack of performance analysis for a coupled greywater treatment plant in single houses under actual conditions. This study, therefore, aimed to evaluate the performance of a coupled greywater treatment and investigate the possibility of its implementation in the actual condition of a selected single house.

METHODS
The greywater treatment plant was installed in a single house with five inhabitants and its design was based on an assumption that 50-80% of water consumed is discharged as greywater while the detention time was derived from literature review. Moreover, the water consumption in the house was 40 m 3 /month, therefore, the greywater production was 32 m 3 /month and the detention time was designed not to be more than 1 to 2 days to avoid odor formation and the greywater turning blackish (Liu et al., 2010). The greywater stream was derived from the kitchen, washing machine, hand basin, and bathroom wastewater and the treatment units consist of sedimentation, filtration, phytoremediation, and disinfection chamber as shown in Figure 1. The treated greywater was used for garden watering and small fish pond while the overflow was discharged to the drainage channel. Furthermore, the flowrate, detention time, and the dimension of each unit of the greywater treatment plant are listed in Table 1 while the description for each treatment is presented in Table 2.   There are two compartments separated by a baffle in the chamber. The first compartment was intended to retain most of the solids and also to function as the grease and fat trap. The second compartment receives relatively clean greywater with fewer solids.
Two-compartment chamber. Cover Inlet and outlet pipe.

Filtration Chamber
Four filter media and a supporting medium were arranged in the filter, as described in the component column.

Filtration chamber
Filter Media: first layer (cotton filter), the second layer (silica sand), the third layer (small gravel), fourth layer (zeolite) (Widiastuti et al., 2008) Supporting Medium: Gravel Inlet and outlet pipe Phytoremediation Chamber The inlet of the phytoremediation chamber was designed using perforated pipes to ensure the flow was distributed equally. This chamber has several plants with the ability to degrade organics. Four plantings were used in this study and arranged from the bottom as gravel, sand, soil, and garden gravel which were used for aesthetics. The greywater flows underneath the soil and plants in the form of horizontal sub-surface flow while the effluent was released to the disinfection chamber. The plants were selected based on their capabilities to remove organics and nutrients and also based on their aesthetics as shown in Figure 2 due to the intention to use them as garden plants. Previous studies have shown the ability of Echinodorus palaefolius, Equisetum hyemale, Cyperus alternifolius, and Typha angustifolia L to remove organics with the percentage listed in Table 3 (Kasman, Herawati, and Aryani, 2018;Suprihatin, 2014;Suswati and Wibisono, 2013;Wahyudianto et al., 2019)and also have the ability to remove some nutrients.  The water quality was analyzed with the focus on the parameters such as pH, BOD, TSS, Phosphate, and ammonia and each was analyzed in line with the procedure stipulated by the Indonesian National Standard (SNI) as shown in Table 4.

Quantity of Greywater
The average flow over 14 days was observed to be 1,111 L/day and this corresponds to 222 L per capita per day while the daily average flow measured during the study period approached the design flow of 1,333 L/day. The daily flow was nearly similar to the values recorded in another research conducted in Malaysia with the freshwater consumption estimated at 226 L per capita per day (Oh et al., 2018). Moreover, a study conducted in 2015 reported the greywater flow in Indonesia to be approximately 60-178 l/c/d and this is much more similar to those produced in Vietnam which was estimated at 80-110 l/c/d (Firdayati et al., 2015) as shown in Table 5. The greywater flow in this study was much higher compared to the existing study in Bandung, Indonesia but it is important to note that its production depends more on water consumption. Meanwhile, a study reported water consumption to be different based on the geographical region (Hidayat et al., 2019) and those recorded in Tangerang, Depok, and Bogor found to be 159, 161.5, and 215.4 l/c/d respectively with Bogor which is located in highland and has a colder climate found to have relatively more water source. The inhabitants of Bogor consume more water compared to the other regions. Furthermore, Magelang is another region in highland with a colder climate and its inhabitants typically have high water consumption which was proved in this study by high greywater production. The greywater produced in high quantity is potentially used to replace water consumed indoor and outdoor after it has been appropriately treated to meet the water standard and the possible quantity of the water to be replaced using the treated greywater has been reported to be between 11,17% -13,63% (Hidayat et al., 2019). A survey from Tangerang, Depok, and Bogor showed the respondents prefer to use treated greywater to water their garden but they were willing to increase the quantity as long as it has been appropriately treated. The use of treated greywater for other purposes has also been found to have the capability to save more water consumption. For example, it is used in the U.K. for toilet flushing, shower, baths, and laundry which constitute 68% of total potable water consumption (Liu et al., 2010).

Quality of Greywater
Significant amounts of organic matter, suspended solids, nitrogen compounds, and pathogens were recorded and compared with the domestic wastewater standard issued by the Provincial Regulation of Central Java No. 5 of 2012 and Indonesia Government Regulation No. 82 of 2001 (see Table 6) to determine the quality of influent and effluent of greywater treatment. The BOD/COD ratio in the influent was found to be 0,95 and this means the greywater contains more easily degradable organic material which is easily treatable using the biological treatment. Meanwhile, the concentration of wastewater effluent for many parameters was found to be below standards with only TSS observed to be higher than both standards. In contrast, BOD was discovered to be the only parameter which exceeded class 3 in Indonesia Government Regulation No. 82 of 2001, and the water in this class is only intended to be used for irrigation and fishery but only for a few fish such as catfish and tilapia. Moreover, ammonia was also one of the parameters which exceeded the standard regulation of the Province of Central Java and this means the combined treatment was unable to treat the nutrient content properly.
The greywater characteristics in this study were compared with other studies and the results are presented in Table 7. The significant organic matters, suspended solids, and ammonia were recorded in the influent and due to the derivation of greywater from the wastewaters from kitchen, bathroom, and laundry, the highest source of organic matter and ammonia most likely come from detergent while the TSS is from kitchen waste. Moreover, the pH was increasing during the treatment in a similar pattern with two of the studies presented in Table 7 and this is most probably due to the release of CO2 from those taken by the plants or the supply of oxygen in the greywater. The table shows the greywater characteristics produced in the houses vary widely depending on the size and residents' habits (Fountoulakis et al., 2016).  Table 8 shows the overall performance of the phytoremediation in this study and others which used phytoremediation and another method to treat greywater and the efficiency in removing organics was observed. The results showed E.coli decreased significantly particularly with the application of submerged membrane bioreactor (SMBR) but the reduction was lesser in the phytoremediation and plant treatment method at 18% to 99%. Meanwhile, the lesser removal of these pathogenic bacteria was associated with the ineffective treatment of plants in filtering the bacteria on its roots. The solar disinfection method was, however, observed to have the ability to assist in this condition but this depends on the depth of the disinfection chamber. Moreover, the removal of nutrients in the form of ammonia and heavy metals were also observed to be low due to the intention of the plant treatment to mostly remove organics rather than nutrients. Therefore, the phytoremediation or another plant treatment method was found to be ineffective in removing nutrient and pathogenic bacteria.
Further treatment is required to remove nutrient and pathogenic bacteria because the water produced from the phytoremediation process in this study does not fulfill the quality guidelines for toilet flushing in the U.K., Australia, and the USA (see Table 9). The treated greywater was observed to be more suitable for irrigation purposes due to the fact that the concentration for all the parameters is within the range allowed for irrigation and fishery for insensitive fish based on the Standard Regulation issued by the Indonesian Government Regulation No. 82 of 2001. 54

CONCLUSION
A high volume of treated greywater in this study was found to be used as alternative water sources in households but the intake is very much dependent on the health and safety perception of the user. Moreover, greywater treatment technology is one of the factors considered to be important to the determination of the level of health and safety of the user. Therefore, this study evaluated the efficiency of a combined phytoremediationsolar disinfection treatment to reduce pollutants in greywater. The results showed the organic removal efficiency was 92% and 83% for BOD5 and COD respectively while the solids content had a smaller efficiency of 49% and ammonia concentration and pathogenic component was reduced by 57% and 88% respectively. The greywater produced in this single household contained a significant TSS, organic, nutrient, metal, and pathogenic bacteria and the combined phytoremediationsolar UV treatment was able to effectively treat the organics but had low removal efficiency for suspended solids, nutrients, metal, and pathogenic bacteria. Furthermore, the comparison of the results for the water quality standard for toilet flushing and water quality in this study showed the treated greywater did not fulfill the required standard but can be used for irrigation and fishery, particularly for insensitive fish such as catfish and tilapia. This research showed the treatment technique using plants and solar UV treatment is not yet able to provide treated water to replace the water consumption within the household despite the high flowrate of greywater. Therefore, a more advanced treatment method such as Submerged Membrane Bioreactor is recommended to be applied in order to maximize the intake of treated greywater for indoor and outdoor uses.

DISCLAIMER
The authors declare no conflict of interest.