Simultaneous removal of carbon, nitrogen and phosphorus (CNP) in a single bioreactor is of high significance in terms of reactor volume and energy consumption. Therefore, in this study, an innovative up-flow anaerobic/aerobic/anoxic bioreactor (UAAASB) augmented by ultrasound was developed as a high rate single bioreactor for the simultaneous removal of nutrients from a milk processing wastewater. The ultrasonic irradiation used in this work was in the range of high frequency (1.7 MHz). The central composite design (CCD) and response surface methodology (RSM) were applied to design the experimental conditions, model obtained data, and optimize the process. The effects of three independent variables, i.e. hydraulic retention time (HRT), aeration mode and mixed liquor suspended solid (MLSS) concentration on 10 process responses were investigated. The results prove that the ultrasonic irradiation has a positive effect on the sludge settling velocity and effluent turbidity. The optimum conditions were determined as 12-15 h, 4000-5000 mg/l and 1.5-2 for HRT, MLSS concentration and aeration mode, respectively, based on removal efficiency of sCOD ⩾ 90%, TN and TP ⩾ 50%.

Recent research proclivity is about supplying water for drinking, urban and industrial applications which is recognized as one of the most significant challenges that threaten humanity. Giving its simplicity and high efficient yield, membrane technology has been preferred compared to other separation technologies for water and wastewater treatment. In the present research, KIT-6 (KIT: Korea Advanced Institute of Science and Technology) was functionalized by H-acid to improve hydrophilic functional groups on KIT-6 surface. Different characterization tests were performed to prove the insertion of H-acid on KIT-6 (H-KIT-6), e.g., FT-IR, XRD, zeta potential and FESEM analysis. Also, the effects of different loading of KIT-6 and H-KIT-6 on the morphology, characteristics and performance of Polysulfone (PSf) nanofiltration (NF) membranes were investigated. The maximum pure water flux (30.2 kg/m² h), the lowest irreversible fouling ratio (3.96%) and the highest flux recovery ratio (96.04%) were obtained for the membrane embedded with 0.1 wt.% H-KIT-6 (optimum membrane). Also, the performance of the synthesized membranes was evaluated by rejection of four different salts (K₂SO₄, MgSO₄, KCl and NaCl) and heavy metal ions (As³⁺ and Hg²⁺). The NF membrane embedded with 0.1 wt.% H-KIT-6 also presented the highest rejection of different salts and heavy metal ions (As³⁺ = 99.85% and Hg²⁺ = 99.27%) compared to the others. Finally, the performance of the optimum membrane to treat a real case of Gachsaran brackish water was assessed. As a result, by applying the optimum membrane, 565 mg/l, 28 mg/l and 27 mg/l of Ca²⁺, SO₄²⁻ and Mg²⁺ were rejected, respectively.