Next Article in Journal
Embedded Hybrid Model (CNN–ML) for Fault Diagnosis of Photovoltaic Modules Using Thermographic Images
Previous Article in Journal
Predictive Modeling and Computer Vision-Based Decision Support to Optimize Resource Use in Vertical Farms
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Sustainability
Volume 15
Issue 10
10.3390/su15107814
sustainability-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Study on the Efficiency of a Hydroponic Treatment for Removing Organic Loading from Wastewater and Its Application as a Nutrient for the “Amaranthus campestris” Plant for Sustainability

by
J. M. Aishwarya
and
R. Vidhya
*
Institute of Remote Sensing, Anna University, Chennai 600025, India
*
Author to whom correspondence should be addressed.
Sustainability 2023, 15(10), 7814; https://doi.org/10.3390/su15107814
Submission received: 3 March 2023 / Revised: 17 April 2023 / Accepted: 29 April 2023 / Published: 10 May 2023
(This article belongs to the Section Environmental Sustainability and Applications)
Browse Figures
Versions Notes

Abstract

:
The investments needed for treating the wastewater produced by an ever-growing population has raised serious concerns regarding the environmental upkeep of many cities across the world. The concept of the circular economy in this context, i.e., the reuse of partially treated water to produce hydroponic plants, is the central idea of this paper. Usage of partially treated (secondary treated) wastewater for the growth of Amaranthus campestris is investigated. The many benefits here are the cost reduction in the treatment process, the reuse of water for commercial plants, the use of treated water, and no pressure on soil all address sustainable development goals such as zero hunger, no poverty, clean water, and sanitation. This study focuses on the degree of pollutant removal using Amaranthus campestris, a local green widely used in India. Secondary-treated domestic wastewater was fed to the hydroponic medium through batches by using an aerobic process, and the hydraulic retention time was maintained for 10 days. In addition to wastewater, a commercial hydroponic solution was added. This study was carried out to verify the reduction in organic loading in wastewater and the growth of plants in comparison with commercial hydroponic solutions. The total COD and BOD removal was significant (p < 0.0009), ranging from 58.5% to 72.5% and 80% to 82.5%, respectively, from the 0th day to the 50th day. After treatment, the lowest nitrogen, potassium, and phosphorus values in DWW were 2.4 mg/L, 5.4 mg/L, and 0.41 mg/L, found on the 20th, 30th, and 40th days of the experiment, respectively. It was also proven that the treated wastewater from the outlet of the hydroponic reactor was within the standard limits and safe to discharge into water bodies. Based on these results, it is encouraging to implement this method at a large scale in small local communities at a lower cost because of its simplified design in promoting a water-based circular economy, which has been proven to reduce carbon footprints, thus supporting a green environment.

Graphical Abstract

1. Introduction

1.1. Population Growth: Increasing Water Scarcity and Food Demands

Population growth and its increasing demand for freshwater are major environmental concerns in both urban and rural areas in India. This demand for freshwater and food production is going to increase in the future because of rapid urbanization [1]. Due to this demand, it is important to find energy-efficient solutions for water scarcity and food supply [2,3]. The United Nations World Water Development Report (2018) reported that water scarcity and the availability of clean water will become worse by 2050, and this will affect world economic growth [4]. The water shortage resulting from economic and population growth is considered one of the most important problems and a hindrance to sustainable development [5]. Developed countries provide better human welfare but are locked into larger environmental and material footprints, which must be fundamentally reduced to achieve Sustainable Development Goal (SDG) 12—Responsible Consumption and Production [6,7]. India is the largest user of freshwater in the world. According to [2], the amount of freshwater needed for irrigation in India will be 611 BCM in 2025. India has 18% of the world’s population and 4% of the world’s freshwater, of which 80% is used in agriculture, which is highly controversial [8]. The availability of freshwater also determines the nation’s economy and growth [9]. Up to 80% of all surface water in India is polluted. The over-exploitation of water resources has deteriorated water quality and quantity for irrigation [10]. Poor sewage treatment facilities, inadequate public sanitation, poverty, industrial runoff, and a lack of government regulations have led to the deterioration of groundwater [3,11]. India is not a water-deficit country but severely lacks water-monitoring developmental projects. It is estimated that the availability of freshwater will decrease in 2051 in Indian cities, and it is necessary to achieve 100% wastewater treatment in India [12]. Wastewater treatment technologies using natural methods are gaining popularity worldwide [13]. According to the UN World Water Development Report (18 March 2019), the global demand for water for production will increase by 20 to 30%. The major areas of freshwater application are agriculture and domestic usage. Agriculture is the major use of freshwater (80–90%), but the demand for freshwater has tripled since 1950 [14]. Therefore, providing freshwater for domestic usage and looking for alternative irrigation methods is important.

1.2. Wastewater Generation and Treatment

India has wastewater generation of about 61,754 MLD (million liters/day) [15], out of which 38,791 MLD are left untreated (Water and Agriculture in India). The CPCB Annual Report 2004-05 [16], stated that 22,900 MLD of domestic wastewater has been generated from urban centers, whereas industrial wastewater generation is around 13,500 MLD. The heavy organic loading in wastewater, nitrogen, and phosphorus content can cause potential hazards to freshwater bodies [17,18]. Nitrogen, in the form of nitrate, is an essential nutrient for plant growth, but the excessive release of nitrogen causes adverse effects on the environment [19,20].
The main nutrients needed for healthy plant growth, N-P-K (nitrogen, potassium, and phosphorous), are artificially provided through manures in traditional agricultural practices. These nutrients are naturally available in wastewater, which can be used as a nutrient medium for plant growth [21,22].

1.3. Why Hydroponics?

The agricultural sector uses the most freshwater in India. There is a tremendous loss of water in spray irrigation and even drip irrigation [23]. Current agricultural practices mainly depend upon land and freshwater and are at risk of natural calamities; hence, it is essential to figure out an alternative methodology [24]. For the projected demand for freshwater for human consumption, partially treated water is one of the best nutrient sources for agriculture. Nutrients from wastewater can be a valuable resource for food production [25]. Protected or hydroponic greenhouse cultivation is the only condition for a suitable environment for better crop production [26]. It will be a breakthrough if freshwater used for irrigation is replaced with partially treated wastewater [27].
Hydroponics is a common way to grow plants without soil in a controlled condition by providing a nutrient solution [28]. Hydroponic production integrated with wastewater treatment systems has various advantages: it has a higher yield than traditional farming through proper maintenance [29,30,31,32], requires no soil, encourages urban farming [33], can overcome soil-borne diseases [34], can be an alternative to freshwater in the agricultural field [35], removes microorganisms to the standard limit [36], and has greater water use efficiency than traditional farming and cost effective [37,38]. The future issue of freshwater demand and increased productivity can be achieved if this technique is adopted in urban and rural areas [39,40]. Most wastewater comprises organic loading, nitrogen, phosphorus, and potassium. The hydroponic system recovers nutrition from wastewater using this integrated system, thus leaving the outlet water within standards. It has been observed that integrating hydroponic irrigation with the effluent treatment process is an ecological alternative to removing nutrients from wastewater through plant uptake [41,42,43] and the substrate media can be reused [44]. Hence, this system will be a promising technology for wastewater treatment and food production [45,46].
This study was conducted to understand the application of wastewater as a nutrient source for hydroponic cultivation, the outcome of the plant’s growth, and the reduction in organic loading after hydroponic treatment.

2. Materials and Methodology

2.1. Plant Selection

The plant chosen for this study is Amaranthus campestris, belonging to the family Amaranthaceae. This local green leafy plant is widely used for its leaves and seed production [47]. Amaranthus is a warm-season vegetable crop, and the optimum temperature for growing this crop is 22 °C to 30 °C. It is increasing in popularity due to its favorable agronomic traits, including rapid growth rates; C4 photosynthesis; dual-uses for vegetable (leaf) and grain (seed) production; and tolerance to heat, drought, and salinity stress. Ref. [48] studied the hydroponic cultivation of Amaranthus in Kenya to meet nutritional demands and analyzed its economic viability. Amaranthus is an underutilized leafy vegetable that can eradicate malnutrition in developing countries [49].
Crop species play an important role in the scope of hydroponic systems that treat municipal wastewater, not only via direct nutrient uptake or promoting microbial activity but also in ensuring the acceptance and implementation of this kind of technology in urban areas [50,51] stated that COD removal depends upon the type of plants and the quantity of the plants used. Amaranthus is an annual and tropical plant that is usually grown in East and South Asia. The cultivation period of the crop ranges from 45 to 60 days. It is a drought-resistant crop. This plant’s leaves and tender stem are rich in protein, minerals, vitamin A, and vitamin C.

2.2. Nutrient Sources

Secondary-treated wastewater collected from a sewage treatment plant located at Anna University Chennai, India, was used as a nutrient source. The concentration and composition of nutrient solutions play a major role in plant growth [52]. This process is an integrated methodology of various factors, including bacteria, water, the sun, and the roots of the plants, which directly or indirectly promote water treatment [53]. In addition to the wastewater, commercially available hydroponic nutrient was added to the wastewater to determine the plant’s growth rate. Reference [54] stated that hydroponically grown roses using wastewater as a nutrient solution were larger than fertilizer-grown roses. The commercially available hydroponic nutrient solution was made by mixing 5 mL (half strength) in 1 lit of RO (reverse osmosis) reject water, which is recommended for leafy vegetables. The hydroponic solution has Ca, 23%; N, 23%; P, 7%; K, 32%; Mg, 5.3%; S, 9%; and microelements (B, Cl, Mn, Zn, Cu, Na, Fe, C), 0.7%. Later, the strength of CHS (commercial hydroponic solution) was increased to 10 mL (full strength) as the plant growth increased [55].

2.3. Hydroponic Setup

A small-scale deep-water culture hydroponic setup was constructed with two units, each having a carrying capacity of 12 plants, as shown in Figure 1. The experiment was conducted in a plastic container filled with 7 liters of nutrient solution. The experiment was conducted for three months. The size of the plastic container was 43 × 30.5 × 14 cm3. Commercially available Amaranthus Campestris seeds (green and red) were chosen for the experiment. Healthy seeds were chosen carefully, and the seeds were soaked in municipal water for about 12 h. Then, they were sown in a medium, and after a few days of germination, the saplings were transferred to a hydroponic setup. An open hydroponic system was chosen for this study since it allows nutritional changes in every cycle to find out the removal efficiency of the system. In closed a hydroponic system, nutrition is recirculated, and the concentration of the nutrition should be monitored.
To support the plants, clay pebbles were filled in plastic pots 6 × 3.8 × 0.51 cm in size. The plastic pots and plants were placed in the plastic container, over which holes were made to set up the plants. Clay pebbles were used because they can retain moisture, have excellent capillary action, and have a neutral pH value [56]. Artificial grow lights were fixed since the setup was made indoors. The wavelength of artificial light ranges from 380 to 740 nm, whereas the wavelength of natural sunlight ranges between 400 and 700 nm [57]. Artificial lighting was provided around 11–12 h/day. and higher light intensity could increase plant growth [58]. An artificial air pump was set up in the hydroponic medium to ensure aeration, and the air stone was immersed in the nutrient solution. This increases the DO (dissolved oxygen) value and provides a better oxygen supply for the roots in contact with the wastewater.

3. Experimental Process

This study focuses on the possibilities of applying wastewater as a liquid nutrient for the plant Amaranthus campestris. A pilot-scale experiment was conducted under controlled environmental conditions to study the growth of Amaranthus campestris in effluent generated from Anna University sewage treatment plant wastewater and compare it with a commercial nutrient solution used as a control medium.
Secondary-treated effluents of 10 L were collected from the sewage treatment plant at ten days intervals. The collected samples were analyzed for physiochemical parameters, including pH, alkalinity, DO, TSS, TDS, EC, BOD, COD, and heavy metals. Unit 1 was fed 7 liters of raw domestic wastewater, and Unit 2 was fed domestic wastewater with a half-strength (5 mL) commercial hydroponic solution. The nutrient was changed every 10 days, and the samples were collected at 10, 20, 30, 40, and 50 days. The continuous aeration allows the roots to be submerged within the nutrient solution [59]. A hydraulic retention time of 10 days was used for this experiment.

4. Observation and Analysis

The plants were observed throughout the experimental process for nutrition uptake, and a few yellowing leaves were spotted. After the initial transformation of the saplings with the nutrition film, a few plants shed yellow leaves. This may be due to the lack of nitrogen in the wastewater. In contrast, the wastewater plus control-medium plants had good growth, which may be due to adequate nutrition from the commercial hydroponic solution. The plants were harvested after 50 days and observed for various physio-chemical parameters, which are noted in Table 1.
Data interpretation and statistical analysis were conducted using Origin, MS Excel 2021, and ANOVA (analysis of variance)—single factor. The analysis value obtained from the hydroponic reactor for the hydraulic retention time of 10 days at various intervals, that is, the 0th day, 10 days, 20 days, 30 days, 40 days, and 50th day, were subjected to statistical analysis, and the efficiency of pollutant removal for parameters BOD3 and COD were calculated using Equation (1):
Efficiency   η   ( % ) = I n l e t − o u t l e t I n l e t × 100

5. Results and Discussion

The efficiency of the hydroponic reactor was calculated using various parameters, such as reduction in DO, BOD, and COD and the removal of nitrogen and phosphorus from the sewage effluent. The main pollutants in sewage effluents are organic loading, nitrogen, and phosphorus. This may vary depending on the season and the types of pollutants present in the water. Standard methods were used to analyze the physio-chemical parameters. A hydroponic reactor treated the sewage wastewater in batches with a hydraulic retention time of 10 days. The temperature of the closed system ranged from 25 °C to 30 °C. The plant chosen is a local tropical plant; hence, the atmospheric temperature has no great effect on the plant’s growth. Figure 2 and Figure 3 show the growth of plants in domestic wastewater and domestic wastewater + commercial hydroponic solution, respectively, during the 15th day of the experiment and the 40th day of the experiment.
The pH of the wastewater varied from 6.9 to 7.28, as shown in Figure 4. The pH value on the 0th day was 6.9, which varied throughout the experimental process, and at the end of the 50th day, it increased to 7.28. Similarly, the pH of the STP effluent + CHS nutrient solution ranged from 7.1 to 7.3, which is closer to the neutral condition. However, the pH range had no significant effect on the growth of the Amaranthus campestris. The difference in the pH value of the wastewater throughout the experiment is noted in Figure 4.

5.1. BOD, COD, and DO Removal

The total COD removal in the wastewater was calculated throughout the experiment with HRTs (hydraulic retention times) of 10 days. COD is the amount of oxygen needed to oxidize the organic matter present in wastewater. It is also used to determine the number of inorganic chemicals in wastewater. Changes in the COD value in the hydroponic reactor and the removal efficiency of COD in the hydroponic reactor are shown in Table 2 and Figure 5, respectively.
The COD value in the wastewater before pre-treatment was 110 mg/L and the post treatment values are 45.57, 46.25, 30.8, and 34.58 mg/L at ten days interval A maximum COD removal of 72.5% efficiency was noted on the 40th day of the treatment, which is significant, as per Table 3 (p < 0.0009). This may be due to the maximum nutrient uptake of the plants during that growth period. Since the water was aerated, it encouraged the growth of microorganisms stuck to the plants’ roots, which may be responsible for the maximum efficiency during the 40th day of plant growth. The COD removal efficiency may vary if the number of plants is different. The maximum efficiency was noted on the 40th day of the experiment.
The biological oxygen demand is the amount of DO required by the bacteria to decompose the organic waste present in wastewater. The amount of oxygen available in wastewater for the use of bacterial species is called dissolved oxygen. Usually, untreated wastewater has heavy organic loading after treatment, which is taken by microorganisms, leaving the water pollution-free. The initial DO value will be very low; after an aeration treatment, the DO will increase, resulting in purified water. During this hydroponic treatment, the initial BOD3 value was 40 mg/L after treatment, which dropped to a lower value of 6 mg/L, achieved during the 40th day. The value of BOD may still decrease on BOD5 calculation. The maximum BOD removal efficiency was achieved on the 40th day of the experiment, which was 85% (p < 0.0009). The BOD and DO values are provided in Figure 6 and Table 1.

5.2. Total Nitrogen, Potassium, and Phosphorous Removal

The essential nutrients for plant growth are nitrogen, phosphorous, and potassium, which are popularly termed N-P-K. Nitrogen is available in the form of NH4+ (ammonium) and NO3− (nitrate). A deficiency of nitrogen causes the yellowing of leaves and shedding. This nitrogen is naturally available in wastewater and can be utilized for plant uptake. In the aerobic hydroponic reactor, ammonium (NH4+) is converted into nitrite (NO2−), which then reacts with Nitrobacter and converts into non-toxic nitrate (NO3−). Figure 6 shows the nitrogen, phosphorous, and potassium removal. Nitrogen absorption was high on the 20th day of the experiment. In the experiment, it was found that the hydroponic reactor could be an optimum source for removing nitrogen pollutants from wastewater. The process of nitrification is responsible for converting nitrogen into nitrite and nitrite into nitrate. The value of the total nitrogen in wastewater ranges from 5.6 mg/L (secondary-treated) to 2.7 mg/L. The minimum nitrogen value was noted on the 20th day, which was 2.4 mg/L.
Similar to nitrogen, potassium is also essential for plant growth. The phosphorous will be taken by the plant in the form of an anion. The different forms of phosphorous are H2PO4− (dihydrogenphosphate), HPO42−(hydrogen phosphate), and PO43− (phosphate). The anion is dependent on the pH of the soil. pH values between 5.5 to 6.5 have adequate phosphorous absorption. In this experiment, the pH value ranged from 6.9 to 7.2. Hence, the phosphorus was not completely absorbed by the plants. This area requires further study to improve the plants’ pH values and phosphorous intake. The initial phosphorous value was 0.51 mg/L; after treatment, it was 0.42 mg/L. Phosphorous is essential for ADP (adenosine diphosphate), which is essential for the flow of energy levels in plant cells, and AMP (activated protein kinase), which regulates cellular metabolism. Similar to phosphorus intake, the absorption of potassium is also low. It is understood that 6.9 mg/L of potassium is enough for the plant growth of Amaranthus campestris. The low potassium level was found on the 40th day of the experiment; the value was 0.41 mg/L. NPK removal is depicted in Figure 7, and the value is represented in Table 1.

6. Cost Analysis

Despite of more production and profit in the hydroponic farming, the initial setup cost is costlier compared with traditional farming. Establishing successful hydroponic farming requires manpower with significant knowledge in this field. However, hydroponic cultivation requires a preliminary economic analysis before project implementation [61]. Table 4 depicts a cost comparison between traditional methods and hydroponic farming.

7. Conclusions

Using wastewater as a nutrient solution for the plant Amaranthus has been proven to be effective in removing organic loading. This study specifically focused on natural wastewater treatment methodologies at minimal cost compared with traditional methods. From this study, it is evident that this methodology and design can be applied on a large scale for both food production and wastewater treatment as a synergetic technology for the plant Amaranthus. In future studies, this methodology can be applied to different local plants for their compatibility with domestic wastewater. The above cost analysis shows that this technique is more economical than the conventional one, and it also reduces the cost of tertiary treatment. This technology can be used as an alternative solution for tackling problems arising in traditional farming methods, thereby promoting a water-based circular economy. By implementing this technology, zero liquid discharge can be assured at the community level. The wastewater produced in a particular community can be recycled and reused within the area. The total organic loading reductions were satisfactory in an aerobic hydroponic reactor. This study reveals that wastewater can be used as an alternative to freshwater in agricultural practices. However, the growth of the plants was relatively good in the STP+CHS unit compared with the STP unit. This may be due to nutrient deficiency in wastewater. Adding commercial solutions to wastewater can increase the plant’s yield. From this study, the COD removal ranged from 58.5% to 72.5% for a hydraulic retention time of 10 days. The removal of COD may be further improved by changing the hydraulic retention time and quantities of plants in each unit. All the values were within the discharge limits with respect to the water quality standards. Similarly, the BOD removal ranged from 77.5% to 85%. Nutrient removals were achieved within satisfactory limits, and the average values of nitrogen, phosphorus, and potassium after the treatment were 2.59 mg/L, 0.44 mg/L, and 5.68 mg/L, respectively. However, this study has some limitations; for example, when applied at a large scale, the area needs a detailed study of cost analysis, implementation hindrance, and manpower for further development to establish community-level wastewater treatments integrated with food production.

Author Contributions

Conceptualization, R.V. and J.M.A.; writing—original draft, J.M.A.; writing—review and editing, R.V.; supervision: R.V.; formal analysis, J.M.A.; methodology, R.V. and J.M.A.; data curation, J.M.A. and R.V. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Not applicable.

Acknowledgments

The sewage treatment plant at Anna University, Chennai, India, for providing samples for this project.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Wada, Y.; Florke, M.; Hanasaki, N.; Eisner, S.; Fischer, G.; Tramberend, S.; Satoh, Y.; Van Vliet, M.T.H.; Yillia, P.; Ringler, C.; et al. Modeling global water use for the 21st century: Water Futures and Solutions (WFaS) initiative and its approaches Developing a Data Provenance Framework View project Integrated Solutions for Water Energy and Land View project Modeling global water use for the 21st century: The Water Futures and Solutions (WFaS) initiative and its approaches. Geosci. Model Dev. Discuss. 2015, 9, 175–222. [Google Scholar] [CrossRef]
  2. Ahmad Bhat, T. An Analysis of Demand and Supply of Water in India. J. Environ. Earth Sci. 2014, 4, 67–72. [Google Scholar]
  3. Rajawat, S. Drought and Water Security in India. In Global Food and Water Crises Research Programme; Future Directions International Pty Ltd.: Perth, Australia, 2016. [Google Scholar]
  4. Boretti, A.; Rosa, L. Reassessing the projections of the World Water Development Report. NPJ Clean Water 2019, 2, 15. [Google Scholar] [CrossRef]
  5. El-Sayed Abdel-Raouf, M.; Elsayed Abdel-Raouf, M.; Maysour, N.E.; Kamal Farag, R.; Mahmoud Abdul-Raheim, A.-R.; Author, C. Green Chemistry Approach for Developing Hydrogels for Agriculture in Egyptian Deserts View Project International Journal of Environment & Agricultural Science Wastewater Treatment Methodologies, Review Article. Int. J. Environ. Agri. Sci. 2019, 3, 18. Available online: https://www.researchgate.net/publication/332183222 (accessed on 12 November 2022).
  6. Sianes, A.; Vega-Muñoz, A.; Tirado-Valencia, P.; Ariza-Montes, A. Impact of the Sustainable Development Goals on the academic research agenda. A scientometric analysis. PLoS ONE 2022, 17, e0265409. [Google Scholar] [CrossRef] [PubMed]
  7. Pradhan, P.; Costa, L.; Rybski, D.; Lucht, W.; Kropp, J. A Systematic Study of Sustainable Development Goal (SDG) Interactions. Earth’s Futur. 2017, 5, 1169–1179. [Google Scholar] [CrossRef]
  8. Dhawan, V. Water and Agriculture in India. Background paper for the South Asia panel during the Global Forum for Food and Agriculture, Federal Ministry of Food and Agriculture. 2017. Available online: https://www.oav.de/fileadmin/user_upload/5_Publikationen/5_Studien/170118_Study_Water_Agriculture_India.pdf (accessed on 29 January 2023).
  9. Kaur, R.; Wani, S.P.; Singh, A.K.; Lal, K. Wastewater production, treatment and use in India. In Proceedings of the National Report Presented at the 2nd Regional Workshop on Safe Use of Wastewater in Agriculture, New Delhi, India, 16–18 May 2012; Available online: https://www.ais.unwater.org/ais/pluginfile.php/356/mod_page/content/128/CountryReport_India.pdf (accessed on 3 January 2023).
  10. AlKaraki, G. Utilization of Treated Sewage Wastewater for Green Forage Production in a Hydroponic System. 2017. Available online: https://www.researchgate.net/publication/279996471_Utilization_of_treated_sewage_wastewater_for_green_forage_production_in_a_hydroponic_system (accessed on 3 January 2023).
  11. Akpor, O.B.; Otohinoyi, D.A.; Olaolu, T.D.; Aderiye, B.I. Pollutants in wastewater effluents: Impacts and Remediation Processes. Int. J. Environ. Res. Earth Sci. 2014, 3, 050–059. [Google Scholar]
  12. Bhardwaj, R.M. Status of Wastewater Generation and Treatment in India. In Proceedings of the International Work Session on Water Statistics, Vienna, Austria, 20–22 June 2005. [Google Scholar]
  13. Marek, K.; Pawęska, K.; Bawiec, A.; Baran, J. Sewage Flow Conditions in a Hydroponic Lagoon in Terms of Quality of Treated Wastewater. Water Air Soil Pollut. 2021, 232, 277. [Google Scholar] [CrossRef]
  14. Hussain, M.I.; Muscolo, A.; Farooq, M.; Ahmad, W. Sustainable use and management of non-conventional water resources for rehabilitation of marginal lands in arid and semiarid environments. In Agricultural Water Management; Elsevier: Amsterdam, The Netherlands, 2019; Volume 221, pp. 462–476. [Google Scholar] [CrossRef]
  15. Bhawan, P.; Nagar, A. Status of Water Supply, Wastewater Generation and Treatment in Class-I Cities & Class-II Towns of India Central Pollution Control Board (Ministry of Environment and Forests, Govt. of India). 2009. Available online: www.cpcb.nic.in (accessed on 14 July 2022).
  16. Sengupta, B. CPCB Annual Report 2004–2005. Central Pollution Control Board, India. Microsoft Word—Annual Report 2004–2005. 2005. Available online: http://cpcbenvis.nic.in/annual_report/AnnualReport_9_annualreport2004-2005.pdf (accessed on 2 February 2023).
  17. Bawiec, A. Efficiency of nitrogen and phosphorus compounds removal in hydroponic wastewater treatment plant. Environ. Technol. 2019, 40, 2062–2072. [Google Scholar] [CrossRef]
  18. Deblonde, T.; Cossu-Leguille, C.; Hartemann, P. Emerging pollutants in wastewater: A review of the literature. Int. J. Hyg. Environ. Health 2011, 214, 442–448. [Google Scholar] [CrossRef]
  19. Farazaki, M.; Gikas, P. Nitrification-denitrification of municipal wastewater without recirculation, using encapsulated microorganisms. J. Environ. Manag. 2019, 242, 258–265. [Google Scholar] [CrossRef] [PubMed]
  20. König, M.; Escher, B.I.; Neale, P.A.; Krauss, M.; Hilscherová, K.; Novák, J.; Teodorović, I.; Schulze, T.; Seidensticker, S.; Hashmi, M.A.K.; et al. Impact of untreated wastewater on a major European river evaluated with a combination of in vitro bioassays and chemical analysis. Environ. Pollut. 2017, 220, 1220–1230. [Google Scholar] [CrossRef] [PubMed]
  21. Magwaza, S.T.; Magwaza, L.S.; Odindo, A.O.; Mditshwa, A.; Buckley, C. Evaluating the feasibility of human excreta-derived material for the production of hydroponically grown tomato plants—Part II: Growth and yield. Agric. Water Manag. 2020, 234, 106115. [Google Scholar] [CrossRef]
  22. Al Meselmani, M.A. Nutrient Solution for Hydroponics. In Soilless Culture; IntechOpen: London, UK, 2022. [Google Scholar] [CrossRef]
  23. Oyama, N.; Nair, J.; Ho, G. Recycling of Treated Domestic Effluent from an on-site Wastewater Treatment System for Hydroponics. 2005. Available online: https://iwaponline.com/wst/article-pdf/51/10/211/433294/211.pdf (accessed on 13 May 2022).
  24. Khan, S.; Purohit, A.; Vadsaria, N. Hydroponics: Current and future state of the art in farming. J. Plant Nutr. 2020, 44, 1515–1538. [Google Scholar] [CrossRef]
  25. Minhas, P.S.; Saha, J.K.; Dotaniya, M.L.; Sarkar, A.; Saha, M. Wastewater irrigation in India: Current status, impacts and response options. Sci. Total Environ. 2022, 808, 152001. [Google Scholar] [CrossRef]
  26. Khan, F.A.A. A review on hydroponic greenhouse cultivation for sustainable agriculture. Int. J. Agric. Environ. Food Sci. 2018, 2, 59–66. [Google Scholar] [CrossRef]
  27. Mavrogianopoulos, G.; Vogli, V.; Kyritsis, S. Use of wastewater as a nutrient solution in a closed gravel hydroponic culture of giant reed (Arundo donax). Bioresour. Technol. 2001, 82, 103–107. [Google Scholar] [CrossRef] [PubMed]
  28. Sharma, N.; Acharya, S.; Kumar, K.; Singh, N.; Chaurasia, O.P. Hydroponics as an advanced technique for vegetable production: An overview. J. Soil Water Conserv. 2018, 17, 364. [Google Scholar] [CrossRef]
  29. Al-Chalabi, M. Vertical farming: Skyscraper sustainability? Sustain. Cities Soc. 2015, 18, 74–77. [Google Scholar] [CrossRef]
  30. Buyeye, Z. Evaluation of the Resource Use Efficiencies of Small-Scale Vertical Hydroponic Structures against Growing Plants in Soil. Int. J. Agric. Biol. 2022, 27, 60–68. [Google Scholar] [CrossRef]
  31. Gomiero, T. Food quality assessment in organic vs. conventional agricultural produce: Findings and issues. In Applied Soil Ecology; Elsevier: Amsterdam, The Netherlands, 2018; Volume 123, pp. 714–728. [Google Scholar] [CrossRef]
  32. Prazeres, A.R.; Albuquerque, A.; Luz, S.; Jerónimo, E.; Carvalho, F. Hydroponic System: A Promising Biotechnology for Food Production and Wastewater Treatment. In Food Biosynthesis; Elsevier: Amsterdam, The Netherlands, 2017; pp. 317–350. [Google Scholar] [CrossRef]
  33. Frasetya, B.; Harisman, K.; Ramdaniah, N.A.H. The effect of hydroponics systems on the growth of lettuce. IOP Conf. Ser. Mater. Sci. Eng. 2021, 1098, 042115. [Google Scholar] [CrossRef]
  34. Gonnella, M.; Renna, M. The Evolution of Soilless Systems towards Ecological Sustainability in the Perspective of a Circular Economy. Is It Really the Opposite of Organic Agriculture? Agronomy 2021, 11, 950. [Google Scholar] [CrossRef]
  35. Manjunatha, M.; Satyareddi, S.A.; Kumar, B.P.; Hebbara, M. Response of Treated and Untreated Domestic Waste Water Irrigation on Yield, Water Productivity and Economics of Cluster Bean. Int. J. Curr. Microbiol. Appl. Sci. 2019, 8, 2483–2491. [Google Scholar] [CrossRef]
  36. Ottoson, J.; Norstrom, A.; Dalhammar, G. Removal of micro-organisms in a small-scale hydroponics wastewater treatment system. Lett. Appl. Microbiol. 2005, 40, 443–447. [Google Scholar] [CrossRef] [PubMed]
  37. Grewal, H.S.; Maheshwari, B.; Parks, S.E. Water and nutrient use efficiency of a low-cost hydroponic greenhouse for a cucumber crop: An Australian case study. Agric. Water Manag. 2011, 98, 841–846. [Google Scholar] [CrossRef]
  38. Gumisiriza, M.S.; Ndakidemi, P.; Nalunga, A.; Mbega, E.R. Building sustainable societies through vertical soilless farming: A cost-effectiveness analysis on a small-scale non-greenhouse hydroponic system. Sustain. Cities Soc. 2022, 83, 103923. [Google Scholar] [CrossRef]
  39. Magwaza, S.T.; Magwaza, L.S.; Odindo, A.O.; Mditshwa, A.; Buckley, C. Partially treated domestic wastewater as a nutrient source for tomatoes (Lycopersicum solanum) grown in a hydroponic system: Effect on nutrient absorption and yield. Heliyon 2020, 6, e05745. [Google Scholar] [CrossRef]
  40. Rababah, A.A.; Ashbolt, N.J. Innovative Production Treatment Hydroponic Farm for Primary Municipal Sewage Utilisation. 2005. Available online: www.elsevier.com/locate/watres (accessed on 3 January 2023).
  41. Bliedung, A.; Dockhorn, T.; Germer, J.; Mayerl, C.; Mohr, M. Experiences of running a hydroponic system in a pilot scale for resource-efficient water reuse. J. Water Reuse Desalination 2020, 10, 347–362. [Google Scholar] [CrossRef]
  42. Norström, A.; Larsdotter, K.; Gumaelius, L.; Jansen, J.L.C.; Dalhammar, G. A Small Scale Hydroponics Wastewater Treatment System under Swedish Conditions. 2003. Available online: https://iwaponline.com/wst/article-pdf/48/11-12/161/422031/161.pdf (accessed on 13 May 2022).
  43. Recsetar, M.S.; Fitzsimmons, K.M.; Cuello, J.L.; Hoppe-Jones, C.; Snyder, S.A. Evaluation of a recirculating hydroponic bed bioreactor for removal of contaminants of emerging concern from tertiary-treated wastewater effluent. Chemosphere 2021, 262, 128121. [Google Scholar] [CrossRef]
  44. Diara, C.; Incrocci, L.; Pardossi, A.; Minuto, A. Reusing Greenhouse Growing Media. Acta Hortic. 2012, 927, 793–800. [Google Scholar] [CrossRef]
  45. Egbuikwem, P.N.; Mierzwa, J.C.; Saroj, D.P. Assessment of suspended growth biological process for treatment and reuse of mixed wastewater for irrigation of edible crops under hydroponic conditions. Agric. Water Manag. 2020, 231, 106034. [Google Scholar] [CrossRef]
  46. Haddad, M.; Mizyed, N. Evaluation of various hydroponic techniques as decentralised wastewater treatment and reuse systems. Int. J. Environ. Stud. 2011, 68, 461–476. [Google Scholar] [CrossRef]
  47. Gopalakrishan, B. Growing of Amaranth by Hydroponic Technique. 2018. Available online: https://www.researchgate.net/publication/322476958 (accessed on 15 October 2022).
  48. Croft, M.M.; Hallett, S.G.; Marshall, M.I. Hydroponic production of vegetable Amaranth (Amaranthus cruentus) for improving nutritional security and economic viability in Kenya. Renew. Agric. Food Syst. 2017, 32, 552–561. [Google Scholar] [CrossRef]
  49. Jimoh, M.O.; Okaiyeto, K.; Oguntibeju, O.O.; Laubscher, C.P. A Systematic Review on Amaranthus-Related Research. Horticulturae 2022, 8, 239. [Google Scholar] [CrossRef]
  50. Magwaza, S.T.; Magwaza, L.S.; Odindo, A.O.; Mditshwa, A. Hydroponic technology as decentralised system for domestic wastewater treatment and vegetable production in urban agriculture: A review. In Science of the Total Environment; Elsevier: Amsterdam, The Netherlands, 2019; Volume 698. [Google Scholar] [CrossRef]
  51. Keeratiurai, P. Efficiency of Wastewater Treatment with Hydroponics. ARPN J. Agric. Biol. Sci. 2013, 8, 800–805. Available online: http://arpnjournals.com/jabs/research_papers/rp_2013/jabs_1213_625.pdf (accessed on 12 December 2022).
  52. Azad, A.K.; Ishikawa, K.; Diaz-Perez, J.C.; Eaton, T.E.-J.; Takeda, N. Growth and development of komatsuna (Brassica rapa L. Nothovar) in NFT (nutrient film technique) system, as influenced by natural mineral. Agric. Sci. 2013, 4, 1–7. [Google Scholar] [CrossRef]
  53. Gebeyehu, A.; Shebeshe, N.; Kloos, H.; Belay, S. Suitability of nutrients removal from brewery wastewater using a hydroponic technology with Typha latifolia. BMC Biotechnol. 2018, 18, 74. [Google Scholar] [CrossRef] [PubMed]
  54. Monnet, F.; Vaillant, N.; Hitmi, A.; Vernay, P.; Coudret, A.; Sallanon, H. Treatment of domestic wastewater using the nutrient film technique (NFT) to produce horticultural roses. Water Res. 2002, 36, 3489–3496. [Google Scholar] [CrossRef]
  55. Krishnasamy, K.; Nair, J.; Bäuml, B. Hydroponic system for the treatment of anaerobic liquid. Water Sci. Technol. 2012, 65, 1164–1171. [Google Scholar] [CrossRef]
  56. Sheikh, B.A. Hydroponics: Key to Sustain Agriculture in Water Stressed and Urban Environment. Pak. J. Agric. Agric. Eng. Vet. Sci. 2006, 22, 53–57. [Google Scholar]
  57. Liu, J.; van Iersel, M.W. Photosynthetic Physiology of Blue, Green, and Red Light: Light Intensity Effects and Underlying Mechanisms. Front. Plant Sci. 2021, 12, 619987. [Google Scholar] [CrossRef] [PubMed]
  58. Fuentes, D.; Flores, J.; Aguilar, A.; Roblero, R. Response of LED lights intensity on lettuce production in a home vertical farm. Rev. Fac. Agron. 2021, 39, e223920. [Google Scholar] [CrossRef]
  59. Cifuentes-Torres, L.; Mendoza-Espinosa, L.G.; Correa-Reyes, G.; Daesslé, L.W. Hydroponics with wastewater: A review of trends and opportunities. Water Environ. J. 2021, 35, 166–180. [Google Scholar] [CrossRef]
  60. General Standards for Discharge. ANNEXURE-I. Available online: https://www.cpcb.nic.in/GeneralStandards.pdf (accessed on 19 January 2023).
  61. Elmulthum, N.A.; Zeineldin, F.I.; Al-Khateeb, S.A.; Al-Barrak, K.M.; Mohammed, T.A.; Sattar, M.N.; Mohmand, A.S. Water Use Efficiency and Economic Evaluation of the Hydroponic versus Conventional Cultivation Systems for Green Fodder Production in Saudi Arabia. Sustainability 2023, 15, 822. [Google Scholar] [CrossRef]
Sustainability 15 07814 g001 550
Figure 1. Schematic diagram of hydroponic setup.
Figure 1. Schematic diagram of hydroponic setup.
Sustainability 15 07814 g001
Sustainability 15 07814 g002 550
Figure 2. Growth of the plants during the 15th day: (left), DWW; (right), DWW+CHS.
Figure 2. Growth of the plants during the 15th day: (left), DWW; (right), DWW+CHS.
Sustainability 15 07814 g002
Sustainability 15 07814 g003 550
Figure 3. Growth of the plants during the 40th day: (left), DWW; (right), DWW+CHS.
Figure 3. Growth of the plants during the 40th day: (left), DWW; (right), DWW+CHS.
Sustainability 15 07814 g003
Sustainability 15 07814 g004 550
Figure 4. pH value of the wastewater in 10-day intervals.
Figure 4. pH value of the wastewater in 10-day intervals.
Sustainability 15 07814 g004
Sustainability 15 07814 g005 550
Figure 5. Removal efficiency of the BOD and COD of DWW.
Figure 5. Removal efficiency of the BOD and COD of DWW.
Sustainability 15 07814 g005
Sustainability 15 07814 g006 550
Figure 6. Changes in the BOD, COD, and DO values of DWW in 10-day intervals.
Figure 6. Changes in the BOD, COD, and DO values of DWW in 10-day intervals.
Sustainability 15 07814 g006
Sustainability 15 07814 g007 550
Figure 7. NPK removal of DWW.
Figure 7. NPK removal of DWW.
Sustainability 15 07814 g007
Table
Table 1. Physio-chemical parameters analyzed during the experiment.
Table 1. Physio-chemical parameters analyzed during the experiment.
Water Quality ParametersNutrient SolutionBefore Hydroponic Treatment (Input)After Hydroponic Treatment (Output), n = 5Analysis MethodStandard Limits [60]
pH at 27 °CDWW6.97.06 ± 0.254500-H+-B APHA 23rd. Edn. 20176.5–9.0
DWW+CHS6.486.80 ± 0.13
Total alkalinity as CaCO3 (mg/L)DWW16597.4 ± 12.52320-C- APHA 23rd. Edn. 2017NA
DWW+CHS189115 ± 13
DO (mg/L)DWW5.96.58 ± 0.44500-O-C- APHA 23rd. Edn. 2017>6.0
DWW+CHS5.76 ± 0.5
TSS (mg/L)DWW237.2 ± 1.22540-D- APHA 23rd. Edn. 201720
DWW+CHS288.6 ± 3.3
TDS (mg/L)DWW625355.2 ± 43Digital TDS meterNo health-based guideline value is proposed
DWW+CHS748524.8 ± 22.4
BOD (mg/L)DWW407.4 ± 1.65210-B-APHA 23rd. Edn. 201710
DWW+CHS7810.2 ± 1.8
COD (mg/L)DWW110.2538.29 ± 85220-B- APHA 23rd. Edn. 201750
DWW+CHS148.5647.42 ± 12.1
Total Nitrogen (mg/L)DWW5.62.59 ± 0.164500-N-B, C- APHA 23rd. Edn. 201710
DWW+CHS115.92 ± 1.0
Total Phosphorus, P (mg/L)DWW0.510.44 ± 0.044500-P-D APHA 23rd. Edn. 20171
DWW+CHS1.050.88 ± 0.13
Total Potassium, K (mg/L)DWW6.95.68 ± 0.123500-K-B- APHA 23rd. Edn. 2017NA
DWW+CHS9.48.92 ± 0.2
Lead, Pb (mg/L)DWWBDL(DL:0.01)BDL(DL:0.01)3111-B- APHA 23rd. Edn. 20170.01
DWW+CHSBDL(DL:0.01)BDL(DL:0.01)
Arsenic, As (mg/L)DWWBDL(DL:0.05)BDL(DL:0.05)3114-B- APHA 23rd. Edn. 20170.05
DWW+CHSBDL(DL:0.05)BDL(DL:0.05)
Cadmium, Cd (mg/L)DWWBDL(DL:0.01)BDL(DL:0.01)3111-B- APHA 23rd. Edn. 20170.01
DWW+CHSBDL(DL:0.01)BDL(DL:0.01)
Nickel, Ni (mg/L)DWWBDL(DL:0.1)BDL(DL:0.1)3111-B-APHA 23rd. Edn. 20170.1
DWW+CHSBDL(DL:0.1)BDL(DL:0.1)
DWW: domestic wastewater; CHS: commercial hydroponic solution; DL: discharge level; BDL: below discharge level.
Table
Table 2. Organic loading reductions in 10-day HRTs.
Table 2. Organic loading reductions in 10-day HRTs.
DaysBOD Removal %COD Removal %
1058.5080.00
2057.9577.50
3068.3682.50
4072.5085.00
5068.5682.50
Table
Table 3. ANOVA: single-factor analysis (BOD and COD removal).
Table 3. ANOVA: single-factor analysis (BOD and COD removal).
SUMMARY
GroupsCountSumAverageVariance
Column 15325.8765.17443.00358
Column 25407.581.58.125
ANOVA
Source of VariationSSdfMSFp-valueF crit
Between Groups666.34571666.345726.065490.0009245.317655
Within Groups204.5143825.56429
Total870.869
Table
Table 4. Cost comparison between traditional and hydroponic farming.
Table 4. Cost comparison between traditional and hydroponic farming.
Cost of Cultivation for One Acre of Amaranthus via Traditional Farming Source: www.agrifarming.in (Accessed on 26 January 2023)Cost of Cultivation for One Acre of Amaranthus via Hydroponic Farming
Cost of seed/acre = 2.5 kg × 400 = Rs.1000/acreCost of seed/acre = 2.5 kg × 400 = Rs.1000/acre
Cost of land preparation (plowing, preparation of beds) = Rs.4000Cost of rearrangements of setup = Rs.5000 (Approximately)
Cost of sowing = Rs.1500 (Approximately 3 laborers)Cost of sowing = Rs.1500 (Approximately 3 laborers)
Cost of weeding = Rs.2000/sessionLess chance of weeding in hydroponic cultivation
Fertilizer = Rs.15,000Natural wastewater can be used as a fertilizer in hydroponic farming, which eliminates the cost of fertilizer
Cost of miscellaneous activities (land rent, water, electricity) = Rs.4000Maintenance activities (electricity, artificial lights in case of indoor farming) = Rs.10,000(Approximately)
Cost of harvesting = Rs.5000Cost of harvesting = Rs.5000
Cost of transportation = Rs.1000 (Approximately)Cost of transportation = Rs.1000 (Approximately)
Miscellaneous charge approximately 10% = Rs.3500Miscellaneous charge approximately 10% = Rs.3500
Total = Rs.37,500Total = Rs.27,500
Net production of Amaranthus in 1 acre = 10,000 kg (Approximately)Net production of Amaranthus in 1 acre = 10,000 kg (Approximately)
The selling price of 1 kg Amaranthus = Rs.11The selling price of 1 kg Amaranthus = Rs.11
Total net amount for 1 acre = Rs.110,000Total net amount for 1 acre = Rs.110,000
Total profit = 110,000−37,500 = Rs.72,500Total profit = 110,000−27,500 = Rs.82,500
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Aishwarya, J.M.; Vidhya, R. Study on the Efficiency of a Hydroponic Treatment for Removing Organic Loading from Wastewater and Its Application as a Nutrient for the “Amaranthus campestris” Plant for Sustainability. Sustainability 2023, 15, 7814. https://doi.org/10.3390/su15107814

AMA Style

Aishwarya JM, Vidhya R. Study on the Efficiency of a Hydroponic Treatment for Removing Organic Loading from Wastewater and Its Application as a Nutrient for the “Amaranthus campestris” Plant for Sustainability. Sustainability. 2023; 15(10):7814. https://doi.org/10.3390/su15107814

Chicago/Turabian Style

Aishwarya, J. M., and R. Vidhya. 2023. "Study on the Efficiency of a Hydroponic Treatment for Removing Organic Loading from Wastewater and Its Application as a Nutrient for the “Amaranthus campestris” Plant for Sustainability" Sustainability 15, no. 10: 7814. https://doi.org/10.3390/su15107814

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop