Wastewaters from olive mills and pulp and paper mill industries in Jordan have been characterized and treated using laboratory scale anaerobic and aerobic sequencing batch reactors, respectively. Nutrient requirements for these two industrial wastewaters were found to be less than what is usually reported in the literature for C:N:P ratio of 100:5:1 for aerobic treatment and 250:5:1 for anaerobic treatment. This was ascribed to the low biomass observed yield coefficients and relatively low removal efficiencies in these wastewaters. It was found that for anaerobic treatment of olive mills wastewater COD:N:P ratio of about 900:5:1.7 was able to achieve more than 80% COD removal. The observed biomass yield was about 0.06 kg VSS per kg of COD degraded. For extended aeration aerobic treatment of pulp and paper mill wastewater COD:N:P ratio of about 170:5:1.5 was able to achieve more than 75% COD removal. The observed biomass yield was about 0.31 kg VSS per kg of COD degraded. In both these wastewaters nutrients were not added. A simple formula is introduced to calculate nutrient requirements based on removal efficiency and observed biomass yield coefficient. Key words: Olive mill wastewater, anaerobic treatment, aerobic treatment, sequencing batch reactor, biomass yield, nutrient requirement.

This research documents two innovative designs of septic tanks used for onsite wastewater treatment. The designs were implemented and tested as part of a research project focused on innovative decentralized wastewater treatment solutions. The modified septic tanks were tested at different hydraulic loading rates for sufficient periods to effectively evaluate their performance. The two systems were designed with successive anaerobic and aerobic chambers and were differentiated between attached and suspended growth. The systems were operated at detention times of 4.3, 3.2, and 2.6 days. High removal of organic load was achieved under all loading criteria in both systems. Effluent BOD₅ concentration at lower and higher loading rates were found to be less than 15 and 25 mg/L, respectively, representing a removal rate of more than 95%. Nitrogen was also removed but at a lower rate. The highest TN removal was achieved (59%) in the attached growth system at the lowest loading rate. Although two logs of E. coli removal (99%) were achieved in all systems, E. coli numbers were high enough to necessitate further tertiary treatment. The modified septic tanks proved to be a cost-effective technology with low energy and O&M requirements.

The technique of multi-stage desalination with brine recirculation (MSF-BR) is characterized by its high energy demand, necessitating the exploration of efficient operational methods to minimize energy consumption and enhance plant performance. In this research study, Matlab R2021a software was used to apply a genetic algorithm with the aim of determining the optimal values of the operating variables of the MSF-BR system within certain limits, considering energy consumption and feed seawater temperature variation. The study included improving several operational factors, including top brine temperature, steam temperature, feed seawater temperature, cooling water flow rate and make up flow rate, number of station stages, and the stages of the heat rejection section. The optimal maintenance period during the operational year was also determined. The results of the analysis were based on data from the Al-Khafji desalination plant, which consists of 16 stages and has a production capacity of 7,053,393.8 gallons/day. The study aimed to achieve two main objectives: increasing the gain output ratio (GOR) and reducing the proportion of the recovery ratio. The results showed that the optimal period for maintenance is January, where the performance ratio ranges between 0.987 and 9.38, compared to the currently used month of December, where the performance ratio ranges between 1.096 and 9.56. Optimal target values were set at the following operating parameters: 33.3 °C for feed seawater temperature, 98.67 °C for steam temperature, 95.62 °C for brine temperature, 1571.18 kg/s for cooling water flow rate, 1624.24 kg/s for feed water flow rate, 21 stages for the station, and two stages for the heat rejection section. To achieve the highest GOR, the number of stages and heat rejection section should be more than 19 and 2, respectively. In general, to achieve improvements in GOR and reduce energy consumption, it is recommended to maintain Tf in the range of 33–34 °C and set M_cw between 1050 and 1800 kg/s.

Different methods used for the determination of BOD first-order model coefficients were evaluated and compared in terms of their prediction of the first order model equation. Usually, these methods were compared in terms of their prediction of the experimental data obtained in the laboratory, not the first order equation. The least square method, Thomas method, Fujimoto method, and a new method introduced here were evaluated. The new method is based on geometric series and logarithm series expansions of the BOD first-order model. Results have shown that as the k value of the first order model increased, higher errors were observed in the methods evaluated except Fujimoto method and the geometric-logarithm series expansion method.