ASSESSMENT OF TREATMENT EFFICIENCY BY NON-ENERGY CONSUMING AERATION SYSTEM FOR FAECAL SLUDGE MANAGEMENT IN AN EMERGENCY HUMAN SETTLEMENT IN BANGLADESH

Rohingya issue is the world’s fastest growing force displacement crisis. Around 8,99,349 Rohingya people have been driven to seek sanctuary in Bangladesh. In this high densely populated emergency settlement, management of faecal sludge is now-a-days becoming a great challenge with the limited resources and space. Wastewater treatment is an indispensable part of faecal sludge management. This study was carried out to identify the wastewater treatment efficiency of the up-flow filtration system with constructed wetland.

15 samples in total were collected from the treatment plant. Total five sample collection points that were raw wastewater, the outlet point of 1st, 2nd and 3rd filter chamber, the outlet point of constructed wetland of the treatment plant. Samples were collected from each point in three consecutive days. Nine parameters of each samples were analyzed in the laboratory. With the help of the literature review, those parameters were selected. For the characterization of FS as well as wastewater, parameters include inorganic, solids concentration, biological constitutes, nutrients and pathogens should be considered (Henze & Comeau, 2008; Niwagaba et al., 2014; Tchobanoglous et al., 2000). Total suspended and dissolved solid as solids concentration; Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Nitrogen (TN), Ammonia (NH3), Nitrate (NO3-), Total Kjeldahl Nitrogen (TKN), Total Phosphorus (TP) and Phosphate (PO43+) as nutrients are mentioned as important for the characterization of domestic wastewater (Negwamba & Dinka, 2019; Dawood et al. 2017; Hegazy and Gawad, 2016; Kulkarni et al. 2018). From the background study, BOD, COD, pH, EC, nitrate, ammonia, phosphate, TDS and TSS were measured in this study for the assessment of the performance of the treatment plants.

The treatment plant was found good at the removal of excess nutrients though NH3 concentration was not within the standard limit. However, the nutrient removal percentages were high in comparison with other parameters. BOD5 concentration of the final treated water were high that is almost twice than the DoE permissible limit. It is due to that no complete biological unit was present in the treatment process Though the BOD5/COD value of raw wastewater was good enough for treatment. A very partial anaerobic process might happen both in the filtration chamber and constructed wetland. Conventional biological process consumes energy and costs to maintain and operate which is not sustainable in the context of Rohingya emergency settlement. In this study, considering the crisis of energy, a non-energy consuming aeration system has been recommended to incorporate into the existing treatment process. This aeration system has been analyzed theoretically and found efficient to improve the water quality.