This paper investigated the use of ultrasound irradiation to treat real mixed industrial wastewater under various conditions, including single and dual frequencies, variable wastewater strengths, and different operating conditions, including flow rates/residence times. This work is important to evaluate the organics’ removal efficiency and to identify operational control bottlenecks under actual wastewater conditions. The highest removal efficiencies were 69.5% and 31.9% for COD and TOC, respectively, for the high-strength wastewater, which were found to occur at 16 kHz frequencies and 500 ml/min flow rate. The removal efficiencies were slightly less in the case of medium-strength wastewater (66.7 and 25.3% for COD and TOC, respectively). They were found to occur at dual frequencies of 16/20 kHz and 1500 and 1000 ml/min, respectively. For the low-strength wastewater, the efficiencies reached 78.6 and 9.1% for COD and TOC, respectively, at the same frequency and flow rates as the medium-strength wastewater. These findings demonstrated the effectiveness of dual frequency in medium- to low-strength wastewater. Among the organics monitored, chloroform (CHCl3), tetrachloroethene (C2Cl4), 1,4 dichlorobenzene (C6H4Cl2), and dichloromethane (CH2Cl2) exhibited variable removal, and in some cases, the removal was found to be negative, indicating intermediary products as a result of incomplete oxidation of organics. Besides the frequency and flow rate, it was found that the concentration of metals and organics are mostly positive influencers on organics removal. At the same time, TDS and pH have mixed effects, but they positively influence organics' removal at higher flows in a few instances. Additionally, as the residence time decreased, the concentration of organics and the pH negatively influenced organics removal. Doi: 10.28991/CEJ-2025-011-04-013 Full Text: PDF

The wastewater quality alterations due to the use of cleaning agents, sanitisers, and disinfectants, in addition to the accompanying use of water during COVID-19 have potential impacts on wastewater treatment operations. How the characteristics of wastewater could be altered by the COVID-19 pandemic was the concern of this investigation. Daily records of the Ardiya catchment in Kuwait City were examined for the period 2015–2020. Perhaps due to the excessive use of water during 2020 (446 compared to the five-year average of 436 l/c.d) and the corresponding wastewater generation increase (253 compared to the five-year average of 239 l/c.d), the effect of chemical usage on the wastewater quality has dampened. Nonetheless, an increase in the frequency of COD/BOD ratio > 3, TP in the range 6.5 to 8.5, TKN in the range 40 to 50 were observed in 2020, which was not observed during 2015–2019. These COVID-19 related alterations are important to take into consideration in wastewater treatment operations to achieve wastewater treatment targets.

Data was collected on the quality and quantity of wastewater discharged from different petroleum and nonpetroleum industrial sources in Kuwait over a period of one year. A field survey included 75 factories distributed in three industrial areas (Sabhan, Kuwait City, and Shuaiba). Among the industries contacted only 41 agreed to participate in field measurements and wastewater sampling campaign. The questionnaire feedback obtained indicated that the activities of these industries can be categorized into 20 categories including 4 and 37 petroleum and nonpetroleum industries, respectively. The mean quality of wastewater generated in Sabhan industrial area were found to be higher than those of Kuwait City and Shuaiba areas. The inorganic results indicated that high values of total suspended solids (TSS), total dissolved solids (TDS), sulfide, free chlorine, and fluoride were observed in the wastewater of petroleum factories of Shuaiba, while high values of total phosphate, ammonia, total Kjeldahl nitrogen, total nitrogen, and floatables were observed in the wastewater of nonpetroleum factories of Kuwait City. Additionally, organic results indicated that high values of chemical oxygen demand (COD), biochemical oxygen demand (BOD), oil and grease, and total petroleum hydrocarbons (TPHs) were observed in the wastewater of petroleum factories of Shuaiba area. GIS maps were generated for 25 wastewater parameters for the participating 41 factories using ArcView GIS software.