Abstract
The Naval Ships contain holding tanks for the storage of wastewater (black water, grey water, bilge water) generated during their time in the sea. This wastewater is then discharged to either the water body when the vessel is outside regulated water or transferred to in-port facilities for processing. With the implementation of much stringent norm and changes in regulation, the authorities are considering an alternative, i.e., an onboard treatment setup. The project identifies this approach, builds a small-scale treatment plant, and undergoes analysis. The setup includes two bioreactor chambers and a membrane biofilter. The study utilizes membrane bioreactor (MBR) processes. The research related to MBR technology for wastewater treatment has gained limelight as well as its application has increased rapidly. The added membrane helps in retaining biomass effectively, producing a solids-free effluent and preventing unintended sludge wasting. For the study, a synthetic feed solution is fed (composition) to the anoxic bioreactor (1ˢᵗ chamber), then to an microaerobic bioreactor (2ⁿᵈ chamber, due to hydraulic gradient between the 1ˢᵗ and 2ⁿᵈ chamber) and finally fed to a membrane biofilter which gives out an effluent and a waste activated sludge (WAS) due to transmembrane pressure (TMP). The utilization of membrane biofilter for wastewater treatment has both advantages and challenges. The most energy intensive component of a wastewater treatment process is aeration. In a conventional wastewater treatment plant, a higher dissolved oxygen (DO) level is maintained in the aeration basins for the microbial growth and digestion of the organic matters. The study practices a more energy abated approach by maintaining a low dissolved oxygen (DO) level ~ 0.3-1 mg/L. This low DO level is achieved by the utilization of a number of small components including Arduino, relay switch, aquarium pump and a DO sensor From the experiment, we were able to achieve COD (Chemical Oxygen Demand), Ammonium-Nitrogen (NH₄-N) and Nitrate-Nitrogen (NO₃⁻) and Nitrite-Nitrogen (NO₂⁻) removal. The details are in the results and discussion section.