Water waste Management Technique in Self-Sustainable Indoor Aquaponics System

. Proper waste management has been emergent attention in varied human habitats. Following the best practices for waste management is essential for a sustainable living environment. This research work proposes a technology-supported self-sustainable aquaponics environment that automatically manages and controls the system by integrating with IoT technology and Naive Bayes algorithm for automated fish feeding. Water quality is monitored with sensors such as pH, temperature, humidity, dissolved oxygen, and water level sensors. Solid waste of fish is filtered and the nitrification process has been carried out by bio-filter. The water level of the fish tank is monitored and maintained by an auto system. Fish feeding requirements have been attained using ML model. The nutrient film technique-based planting system optimally extracts nutrients. The Vertical farming technique helps to reduce the land and water used for cultivation. The sensors are operated on microcontrollers namely Arduino UNO and Raspberry Pi. The sensed values are communicated through a mobile application for constantly monitoring the aquaponics environment. The prospect shows the self-sustainable smart aquaponic platform for farmers to grow fish and plants in a single system simultaneously to get increased production with fewer natural resources such as land and water.


Introduction
To Overcome the increased food demand, some symbiotic farming plays a vital role.The vegetables and leafy greens are conventionally cultivated using soil as the growing medium.The conventional method of cultivation is labor-intensive with high operating costs and unpredictable yield caused by adverse and volatile weather conditions.Traditional cultivation requires vast resources such as water, fertilizers, and labor.The situation is experienced in most developing countries with occasional high-technology agriculture systems.Aquaponics is an emerging technology that combines aquaculture and hydroponics (growing plants in a nutrient solution) which works interdependently to create an effective aquaponics system [1].Aquaponics will play an important role in the future of social, economic, and environmental sustainability and make important contributions to increasing food production.Because no synthetic fertilizers are used, the process is considered organics and also it decreases operating costs and opens the way for waste management by recirculating nutrient-rich water from aquaculture to hydroponics and vice versa [2].Aquaponic systems, when combined with vertical farming as the growing space is constructed vertically, will boost production yield per square area.In the Aquaponics system, no synthetic fertilizers are used so the production process is considered organics.Aquaponics will play an important role in the future of social, economic, and environmental sustainability and make important contributions to increasing food production [3].This technique significantly decreases operating costs, waste products (e.g., feces, etc.), and chemical fertilizers.The waste products from aquatic life are transformed into nutrients for plants in the growing medium, and plants return clean water to aquatic life.The system is recirculating the nutrient-rich water, so there is minimal water consumption which aids in waste management.Aquaponic systems, when combined with vertical farming, will boost production yield per square area as the growing space is constructed vertically.This proposed system practices with fewer human resources because it operates automatically in a smart way with minimal supervision [4].After the emergence of microcontrollers, sensors, and automated technologies helps in monitoring various parameters to achieve sustainability of the system with minimal human intervention.

Experimental setup
In the proposed system, 5 major components are connected to achieve a self-sustainable indoor smart aquaponics system.They are an aquaculture tank, hydroponics plant grower, biofiltration unit, uninterrupted power and water supply, and smart technologies component.The aquaculture tank is filled with water and tilapia fish seeds [5].The hydroponics grower in this system has shared two grower techniques.They are NFT and vertical growers.The nutrient film technique means the film of water is allowed to flow through the channel filled with media such as stones, perlite, rock wool, coir pith, etc.The media used in this system is light expanded clay aggregate (LECA) is the clay pebbles that are clean, pH stable, and can be reused a few times before replacing it.The next grower technique is the vertical grower technique in which the plant samplings in the net basket are aligned vertically with the thin water flow throughout the middle of the grower as shown in Figure 1.The combination of these two techniques will create more yield in less space.The NFT system is sloped at less than 2% [6] to improve crop productivity.In this system, the slope is settled at 1.0%.Followed by the hydroponics grower the aeroponic tower is connected.The plants are planted vertically in a cylindrical-shaped tower with springles fixed on the vertical axis.The water from the fish tank is pulled out efficiently and transported to the biofilter.The biofilter is the most essential component of this proposed system, here the solid waste (E.g.Feces and uneaten fish food) and the microscopic waste from the water are transformed into nutrientrich water.The water that passes through the biofilter is stored in the sump to control the flow of nutrient water to the plant growers.This separate sump will save power by operating the biofilter by only the sump reaches a particular pre-settled level.So biofilter won't run continuously.The water from the sump is passed through the pipe where the sprinkler is arranged between a 4-inch gap to one another.This operation is initiated by a separate motor.At the end of the NFT system the water flow pipe is directly connected to the vertical grower system in which the sprinkler is arranged vertically in a 5-inch gap throughout the axis and the end of the pipe is closed.The water from the NFT system and vertical grower system will be collected separated and connected back to the fish tank.In this aquaponics system, the quality of water is collected by sensors to detect the level of ammonia (NH3), pH, temperature, dissolved oxygen (DO), NPK levels, and water level in the tank [5].Polyvinyl chloride (PVC) pipes are used to connect the components wherever needed.The fish feeder is automated according to the water quality value obtained from the sensors from the fish tank.The fish feeder has a small outlet for dropping food for 5 seconds.The servo motor feeder will rotate to open or close the feeder on the prediction made by the Naive Bayes algorithm.Because the water sprinklers are used in the system, water evaporation happens.The pumps operate with a fixed spray rate.All units were modeled as biofilter sump motors operating at constant volume.The spray rate for the plants in NFT grower is calculated by the following equation.
∅ , is the Volumetric flow rate of water evaporation.Recirculating water enters at rate ∅_(v,in).To refill water, the reservoir opens automatically when the fish tank water level reaches below 75% of the total height.Wi-Fi is based on the 802.11radio standard, which permits data to be sent across limited distances at high frequencies.The 802.11 runs at 2.4 GHz or 5 GHz to enable the system for high-speed data transmission.The sensors collect the data for one hour once with the help of a microcontroller send it to the cloud and store it with the help of a WIFI module ESP8266.The Raspberry Pi3 is a microprocessor that is used to execute the machine learning model by fetching data from the cloud, executing it, and controlling it [12].It initiates the actuators such as the servo motor for the fish feeder, water pump from the fish tank to the biofilter, water motor from the biofilter sump to the growers, and water reservoir control to the fish tank.The biofilter consisted of filtering used for nitrification, i.e., conversion of ammonia, which is toxic for the fish, into less toxic nitrate.
Recirculating water enters at a rate ∅_(v, in) and leaves at a rate ∅_(v, out).Biofiltered water is received in the sump (of pre-fixed volume).An uninterrupted power supply is connected to this system.This system is best suited for indoor with a dedicated UV light system for both growers.The light sensor helps to detect the lighting in this system and operates the dedicated UV light with the help of the controller [7].The overall health of this system is monitored in the Android application in the form of graphs about pH, temperature, dissolved oxygen, and ammonia sensors.For plant growth, nitrogen, phosphorus, and potassium are mandatory macronutrients.The NPK sensor is connected to the controller [13].The real-time data about this system is monitored through an Android application by the users.
The computed data of the machine learning model by Raspberry Pi is also updated in the Android application.The Naïve Bayes algorithm is the algorithm that has been applied in the proposed system for the data analysis in an automatic feeding system.

Naïve Bayes algorithm
The naïve Bayes classifier is based on Bayes theory.In this classifier, all the variables are conditionally independent so that the parameters can be learned individually and quickly [6].
A posterior probability of the predictor P(H|X) [8].
In the above equation, P(H) is the prior class probability, P(H) is the probability of the given class, and P(X) is the prior probability of the predictor.
The set of nodes are variables of a System.Naïve Bayes is used for this proposed system because the inputs from the system are high and give output in a more sophisticated form.The feeder will predict the release of the fish feed from the predicted output of the Naïve Bayes algorithm.When the output is yes, the servo motor will turn on for 2 seconds and release the food.When the output is no, the servo motor will be ideal.

Dissolved Oxygen (DO)
The DO in the aquaponics system is important for optimal fish and plant growth and also for beneficial bacteria that convert toxic ammonia to nitrate [9].The optimum level of DO is >4.0 ppm.For the warmest water species of fish such as tilapia, the DO level below 3.0 ppm will be stressful, and below 2.0 ppm can be deadly.In the proposed system, the 30-day average is >6.0 ppm.Noticed that water hold less oxygen at high temperature.Low oxygen level in water is reflected in fish behaviours, such as appetite loss, Surface gasping, gathering around inflow pipes, reduced growth, and sensitivity to diseases and parasites.

Total Ammonia Nitrogen (Ammonia, Nitrite, Nitrate)
In aquaponics systems, maintaining appropriate levels of total ammonia nitrogen (TAN) is crucial for the health of fish and plants.Ammonia is toxic to fish, and it is a primary waste product excreted by fish in the form of ammonia (NH3) and ammonium ions (NH4+).These compounds can accumulate in the water and harm aquatic life if not properly managed.
The optimum range for total ammonia nitrogen (TAN) in an aquaponics system is generally considered to be less than 1 mg/L (parts per million or ppm).In this range, ammonia concentrations are at levels that are safe for fish and plants.Regular monitoring of ammonia levels is essential, especially in the early stages of setting up an aquaponic system or when adding new fish, to ensure that ammonia concentrations do not reach harmful levels.[10] It's important to note that different species of fish have varying tolerance levels to ammonia, so it's essential to choose fish species that are suitable for the specific conditions of your aquaponics system.Additionally, the presence of nitrifying bacteria in the system helps convert toxic ammonia into less harmful compounds like nitrite and nitrate through the process of biological filtration.Proper filtration and regular water testing are key practices to maintain a healthy balance of ammonia in the aquaponic system.In the proposed system the fish feed will not be released until all the parameters are controlled in normal range.This will help to safeguard the situation from getting worse.

pH
pH is an important factor in fish culture and in wastewater management.This indicates the acid-base balance of the water.The neutral pH is 7; above 7 is alkaline on a scale up to 14 and below 7 is acidic.The growth and survival of the fish depend on the pH range for fish culture is between 6.7 and 9.5.For growth, the ideal pH is between 7.5 and 8.5.The fish are stressed when pH goes above or below this level.When the pH level decreases below 5.5, nitrification has largely ceased TAN concentrations can become extremely elevated.In this system pH probe is used to collect data in regular intervals.

Water Temperature
The optimum water temperature in an aquaponics system depends on the specific plants and fish species you are cultivating.Generally, most aquaponic systems aim for a water temperature range between 20°C to 30°C (68°F to 86°F), as this range is suitable for many common fish species like tilapia, trout, and catfish, as well as a variety of plants including herbs, lettuce, and tomatoes.However, it's crucial to note that different species have different temperature requirements.For example, tilapia thrive in warmer water around 28°C to 30°C (82°F to 86°F), while trout prefer cooler water around 10°C to 20°C (50°F to 68°F).Similarly, some plants may prefer slightly cooler or warmer temperatures.The water temperature is also affecting the oxygen level in the water.Therefore, it's essential to choose fish and plant species that have similar temperature requirements to maintain an optimal aquaponic system.

Nutrients Required for Plant Growth
All type of plants is unique and has an optimum nutrient range and minimum requirement level.Below this level, the plants start to fall into nutrition deficiency.The plants utilize these nutrients efficiently with an adequate supply of light, heat, and water and the proper amount of nutrients is important [11].

Results and Discussion
The Six sensors are connected to the system (DO Sensor, pH sensor, Temperature sensor, Water level sensor, Ammonia sensor, NPK sensor) and growth parameter, the proposed system creates a database to display the gathered data in an Android application.Further, an algorithm is applied to the collected data which has been collected in the cloud database.The Android application through which users can monitor the system remotely.(The parameters retrieved from the system and stored in the cloud).An alarm option is given in the Android application, whenever it exceeds the optimal level, an alarm is given in the user's mobile application.The alarm doesn't mean that it needs compulsory human intervention, it is only for sending the status of the system.The food feeder operates automatically according to the sensor level and the prediction done by the ML model.The system triggers the neutralizing element automatically.The water pump is initiated and the water from the fish tank is pulled out to the biofilter and then to the sump.It means, that the fish tank water will reach its threshold value, and the reservoir water pump is powered on.Now the fish tank is filled with the new water from the reservoir.Now the water parameters are normalized, because of the replacement of water and neutralizing elements.
When the water in the sump reaches a level, NPK solution is added to the water and then the NPK sensor value is calculated.When the value reaches the optimal range the water from the sump is pulled into the NFT system with the help of a water motor.In this smart aquaponics system, NPK sensor data is not stored in the cloud server.Because the NPK sensor value is used whenever the sump is filled with new water from the biofilter.The value of NPK is set to the optimal ranges for herbs and green veggies which are 5,18,20 respectively.Lettuce is planted in the first component called the NFT component.The water from the sump is pulled out and sent through the NFT component, then to the vertical grower.The herbs (mint and basil) are planted in the vertical grower in which the aeroponics technique is used.The water flow pipe is sealed at the end of the vertical grower.The sprayed water residue is sent directly to the fish tank and a pipe outlet from the NFT system sends water residue to the fish tank.This smart aquaponics system is correctly designed and balanced.The feeding ratio is the amount of feed fed to the fish periodically per square meter of plant growing area.For deep water culture systems, the optimum ratio varies from 60 to 100 g/m2/day.In the proposed system the fish tank size is 2.23 m2.The two types of hydroponics techniques are combined such as the NFT system with medium and spray system and aeroponics vertical grower system.The size of the NFT grower bed is 1.11 m2 and the size of the vertical grower is 1.5 m2.The plants in this grower rely on the nutrients in the fish waste into plant nutrients.However, nutrient deficiencies can occur due to imbalanced or inadequate nutrient levels nutrient deficiency can lead to reduced yields, stunted plant growth, and plant death.The problem arose when the DO and pH probes were in the tank at the same time.So, the switch is used to take DO readings and pH readings.DO reading is 2 min delayed after pH readings.Because when each of these probes is taking live readings at the same time there is a voltage interference that translates to a digital error reading.
In this work, the results are recorded to check the system is self-sustainable and that the collected data periodically is used for the further research process.In the below table, the records collected for 30 days prove that the system is self-sustainable.The most important water parameters of an aquaponics system are Ammonia, pH, Temperature, and Dissolved oxygen are maintained in optimal range which is well suited for both plants and Fish.When data are collected from sensors (i.e., pH data, water level, and growth parameter, the proposed system creates a database to display the gathered data.Then an algorithm is applied to the data that has been collected in the database.The Naive Bayes Algorithm has been applied in the proposed system for the data analysis part to predict the operation of the feeding system.The information which has been gathered from the external world is summed up inside the computing unit.This self-sustainable system combines plants and animal production, and optimal water quality is essential to a healthy functioning system.Our initial data collection gave satisfactory readings for the 30 days and the system does not need human intervention.In the 15-day readings shown in Fig. 2. The human can monitor the system remotely and take a few controls in emergencies such as external disturbance to the system.The electricity is mandatory 24/7 because we are using an NFT system in which no water is stored in the plant section.Water flow is needed without any interruption.An extra battery or a solar panel can be established for an uninterrupted power supply.

Conclusion
This smart Aquaponics system is the integration of Aquaculture, NFT system in hydroponics, Vertical growing with aeroponics, and recirculating water in a single system.In an aquaponic unit, water from the fish tank cycles through biofilters, plant grow beds (NFT and Vertical grower), and then back to the fish.In the biofilters, the water is cleaned from the fish wastes by a mechanical filter that removes the solid part and then processes the dissolved wastes.Ammonia is toxic to fish and Nitrate is a more accessible nutrient for plants.With the help of an automated water quality management system for Aquaponics, without human intervention, farmers can monitor the water quality, which helps to improve the efficiency and productivity of the unit.Wastewater has been managed efficiently and productively in the system.Moreover, with the help of a Cloud server and Mobile Application, a door is opened for data analysis which helps to optimize the circulation of water and thus optimize the power requirement for continuous water circulation.The prediction mechanism helps in controlling the system and maintaining the flawless system.Automated self-sustainable aquaponics with the combination of different farming techniques reduces human intervention, waste management, and space minimization with higher production and thus the proposed system will make the lives of people easier and utilize the smaller area with higher production.

Table 1 .
Nutrients Required for Plant Growth.