Performance and Biomass Characteristics of SBRs Treating High-Salinity Wastewater at Presence of Anionic Surfactants

A study on the efficiency of the sequential batch reactor on the reduction of wastewater pollution from oil washing

Industrial pollution discharges from washing fuel oils pose severe problems for the environment, particularly for the marine environment receiving these discharges. This work evaluates the biological treatment performance of wastewater (90 m³/h) rich in organic matter with low biodegradability using a sequential batch reactor (SBR) on a laboratory scale. The test using SBR was carried out for 25 days on a continuous cycle of 24 h (30 min of filling, 17 h of aeration, 4 h of anoxia, 2 h of settling, and 30 min of emptying). The feasibility of alternative sources of microorganisms from urban wastewater. The performance of the batch sequencing reactor was evaluated using turbidity, total suspended solids, chemical oxygen demand (COD), biological oxygen demand (BOD), ammonium, nitrate, and phenol as indicators. The results obtained showed that the COD/BOD ratio and the pollutant load vary from one campaign to another. The removal efficiency of COD, BOD, TSS (Total suspended solids), ammonium, nitrate, and phenol varies from 81%, 91%, 72%, 100%, 52%, and 63%. Thus, SBR-type treatment could be an interesting way to reduce pollution due to its simplicity, less space occupation, low energy consumption, and not requiring highly qualified personnel.

Desalination of Municipal Wastewater Using Forward Osmosis

Membrane technology has gained much ground in water and wastewater treatment over the past couple of decades. This is timely, as the world explores smart, eco-friendly, and cheap water and wastewater treatment technologies in its quest to make potable water and sanitation commonplace in all parts of the world. Against this background, this study investigated forward osmosis (FO) in the removal of salts (chlorides, sulphates, and carbonates) and organics (chemical oxygen demand (COD), turbidity, total suspended solids (TSS), and color) from a synthetic municipal wastewater (MWW), mimicking secondary-treated industrial wastewater, at very low feed and draw solution flow rates (0.16 and 0.14 L/min respectively), using 70 g/L NaCl solution as the draw solution. The results obtained showed an average of 97.67% rejection of SO₄²⁻ and CO₃²⁻ while Cl⁻ was found to enrich the feed solution (FS). An average removal of 88.92% was achieved for the organics. A permeation flux of 5.06 L/m².h was obtained. The kinetics of the ions transport was studied, and was found to fit the second-order kinetic model, with Pearson’s R-values of 0.998 and 0.974 for Cl⁻ and CO₃²⁻ respectively. The study proves FO as a potential technology to desalinate saline MWW.

Comparison of the effects of salinity on microbial community structures and functions in sequencing batch reactors with and without carriers

This study investigated and compared the microbial communities between a sequencing batch reactor (SBR) without carriers and a hybrid SBR with addition of carriers for the treatment of saline wastewater. The two systems were operated over 292 days with alternating aerobic/anoxic mode (temperature: 28℃, salinity: 0.0-3.0%). High removal efficiency of chemical oxygen demand (COD) and total inorganic nitrogen (TIN) was achieved in both the SBR (above 86.7 and 95.4% respectively) and hybrid SBR (above 84.4 and 94.0%) at 0.0-2.5% salinity. Further increasing salinity to 3.0% decreased TIN removal efficiency to 78.4% in the hybrid SBR. Steep decline of biodiversity and relative abundance of ammonia-oxidizing bacteria (AOB) contributed to the worse performance. More genera related to sulfide-oxidizing and sulfate-reducing bacteria were detected in the hybrid SBR than the SBR at 3.0% salinity. The abundance of halotolerant bacteria increased with the salinity increase for both reactors, summing up to 25.5% in the suspended sludge (S-sludge) from the SBR, 28.9 and 22.9% in the S-sludge and biofilm taken from the hybrid SBR, respectively. Nitrification and denitrification via nitrate was the main nitrogen removal pathway in the SBR and hybrid SBR at 0.0 and 0.5% salinity, while partial nitrification and denitrification via nitrite became the key process for nitrogen removal in the two reactors when the salinity was increased to 1.0-3.0%. Higher abundance of anaerobic ammonium-oxidizing (ANAMMOX) and sulfide-oxidizing autotrophic denitrification (SOAD) bacteria were found in the hybrid SBR at 3.0% salinity.