Kinetic investigation and optimization of a sequencing batch reactor for the treatment of textile wastewater

Discharging of untreated or partially treated textile wastewater is common in Ethiopia, and this has detrimental effect to the environment. It is difficult to treat textile wastewater by conventional biological processes. In this study, real textile wastewater was taken and treated using sequencing batch reactor using a biomass taken from domestic wastewater treatment plant. Cycle period, air flowrate and sludge retention time (SRT) were initially optimized using the response surface methodology. The optimum ratio of cycle period/air flowrate/SRT which gives a 57% COD removal and 54% color removal was found to be 25 h/15 L/h/16 day. Using two types of wastewater substrate concentrations and various hydraulic retention times at optimized condition, COD removal, color removal, sludge volume index (SVI) and mixed liquor suspended solid were measured. The maximum of COD removal (73%) and color removal (65.8%) was obtained at an organic loading rate of 0.078 kg COD/m3 day. SVI at the optimized condition was found to be 90–92 mL/g. Finally, a first-order kinetic model was used to represent the degradation of textile wastewater

Chemical Treatment Methods Pilot (CTMP) System for Treatment of Urban Runoff – Phase I. Feasibility and Design

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Cost and Environmental Impacts of Leachate Nitrogen/Phosphorus Management Approaches

Landfill leachate is a challenging wastewater to discharge into municipal wastewater treatment plants (WWTPs), the most common approach for leachate management, due to the presence of contaminants that may affect the performance of the treatment plant. Treatment, disposal, and transportation of leachate are expensive and therefore a concern. Currently, sidestream treatment is becoming increasingly common in WWTPs prior to returning the liquid to the plant influent. For this research, a new treatment scheme is introduced combining centrate and leachate to reduce contaminants, recover phosphorous and nitrogen through struvite precipitation, and reduce energy requirements through anaerobic ammonium oxidation (Anammox). By combining the two waste streams, the respective limited nutrients (nitrogen in centrate and nitrogen in leachate) can be removed in a low cost chemical treatment resources can be recovered. Carbon contaminants and remaining nutrients can be removed in subsequent innovative biological treatment units. The objective of this thesis is to conduct a cost analysis and environmental assessment of the proposed novel treatment approach and to compare it to more traditional landfill on-site leachate treatment approaches (e.g., membrane bioreactors (MBR) and sequencing batch reactors (SBR)). The study was completed with the use of spreadsheet-based models. Spreadsheets have been developed to evaluate treatment costs (Capital + O&M) for both the proposed nutrient recovery/biological and traditional on-site leachate treatments. Transportation costs of leachate to the WWTP have been studied and analyzed by the use of a spreadsheet model as a function of distance. Results suggest that treatment using Struvite – Aerobic Granular Sludge – Anammox (SGA) was higher in cost compared to traditional approaches. However, positive outcomes from this process include: lower N_2 O emissions, lower power consumption, struvite fertilizer, and overall recovery of nitrogen and phosphorus with the combination of centrate and leachate

Field testing of an onsite sanitation system on apartment building blackwater using biological treatment and electrochemical disinfection

The Closed Loop Advanced Sanitation System (CLASS) was designed to treat, disinfect, and recycle toilet blackwater from existing flush toilets in a multi-story apartment building. Two systems were tested at two unique sites in Coimbatore, India for a combined 7500+ treatment hours resulting in more than 180 000 L of treated water. The CLASS prototypes used a combination of biological pretreatment and electrochemical oxidation processes to produce treated water that nearly met the stringent requirements outlined in the standard ISO 30500. The nutrient and organic loading from the toilet blackwater was predominantly reduced by over 85–95% and 80–87%, respectively, through biological processes that were achieved using either a sequencing batch reactor (SBR, site A) or an anaerobic–aerobic biodigester (EcoSan, site B). Complete disinfection of E. coli with nil CFU per ml was achieved using electrochemical processes that also served to remove the remaining organic and nutrient loading to over 90–96%. The treated water was reused for flushing by the residents of the apartment building for 89 days