Excess sludge treatment and disposal is a major challenge for wastewater treatment plants worldwide. In this study, sludge reduction was evaluated using pilot scale sequencing batch reactors (SBRs). Two SBRs were operated alongside each other over a period of 12 months during which time measurements were performed to determine COD, MLSS, MLVSS, pH, DO, SV1, SOUR, and ORP. The results showed that among the different SRT durations (5, 10, 15, 20, 25 days), the 10-day sludge retention time yielded maximum COD removal efficiency (90%) without any bulking or foaming problems. Prior to any reactions taking place in the reactor, the sludge was exposed to various oxidation reduction potentials for 1 to 8 hours in order to determine the effects of uncoupling metabolism on biomass production under different anoxic and anaerobic conditions. COD was observed to decrease from 600 to 33 mg/l while MLSS increased from 1350 to 1500 mg/l over a retention time of 7 hours and for an ORP value of -238 mv. The effluent COD obtained as a result of operating this process was below the limits set by environmental regulations for surface waters and reuse in agriculture. For an ORP value of - 238mv, SOUR and SVI were measured to be 22 mgO2/h.gVSS and 40 ml/g, respectively.

A new approach in this work was the biodegradation of Benzene, Toluene, and Xylene (BTX) using Airlift Parallel Bioreactors (APB’s) connected to the Plexiglas Bio-Scrubber (PBS) Modulated with Polyurethane Foam (MPF) as modified sort in the use of mineral pumice as a porous filler Lava rock media. The aeration bioreactors were set up with a microbial consortium of refinery sludge effluent sewer (SES) treatment and nutrient solution. The performance of PBS for BTX removing by APB’s filled with Activated sludge effluent sewer (ASES) in the range of inlet BTX concentrations from 180.7 to 881.8 ppmv in different air pollutions flow rates was tried for two rates: 2.5 & 3.5 L/min  at 30 days Mean Residence Time Distribution (MRTD) for each treatment. The results showed that at inlet pollutant concentrations of [B] = 180.7 ppmv, [T] = 327.4 ppmv & [X] = 297.5 ppmv, the removal efficiency in flow rate 2.5 lit/min was 90.7, 88, and 83.6(%) for benzene, toluene, and xylene, respectively. The amount of removal in flow rate 2.5 lit/min was better than the removal efficiency of 3.5 lit/min due to lower pollution concentration.

A new approach in this work was the biodegradation of Benzene, Toluene, and Xylene (BTX) using Airlift Parallel Bioreactors (APB’s) connected to the Plexiglas Bio-Scrubber (PBS) Modulated with Polyurethane Foam (MPF) as modified sort in the use of mineral pumice as a porous filler Lava rock media. The aeration bioreactors were set up with a microbial consortium of refinery sludge effluent sewer (SES) treatment and nutrient solution. The performance of PBS for BTX removing by APB’s filled with Activated sludge effluent sewer (ASES) in the range of inlet BTX concentrations from 180.7 to 881.8 ppmv in different air pollutions flow rates was tried for two rates: 2.5 & 3.5 L/min  at 30 days Mean Residence Time Distribution (MRTD) for each treatment. The results showed that at inlet pollutant concentrations of [B] = 180.7 ppmv, [T] = 327.4 ppmv & [X] = 297.5 ppmv, the removal efficiency in flow rate 2.5 lit/min was 90.7, 88, and 83.6(%) for benzene, toluene, and xylene, respectively. The amount of removal in flow rate 2.5 lit/min was better than the removal efficiency of 3.5 lit/min due to lower pollution concentration.

Tympanotonos fuscatus shell (T. fuscatus shell), an abundant eco-friendlywastewas used as a precursor for the production ofTympanotonos fuscatus coagulant (TFC) for the purification of paint effluent (PE).Tympanotonos fuscatus shells (TFS) are of crustacean origin consisting mainly of chitin, calcium carbonate, entrained protein and other organic matrixes. Influence of pH, dosage and settling time on treatment efficiency was studied. Scanning electron microscopic, Fourier transform infra red, X-ray diffraction and differential scanning calorimetric/thermogravimetric analyses were carried out to investigate, respectively, the surface morphology, functional group, crystalline/lattice structure and thermal stability of TFS, TFC and settled sludge after treatment. The PE was optimally treated at 2 g/L TFCdosage, pH 5 and 97 % efficiency. Results indicated that TFC could be an efficient treatment agent for PE at the conditions of the experiment.

ACCORDING TO ENVIRONMENTAL PROTECTION ORGANIZATION OF IRAN, MAXIMUM PERMISSIBLE CONCENTRATION OF RESIDUAL PHOSPHORUS IN TREATED MUNICIPAL WASTEWATER IS 1 MG /1-P. THE TOTAL AVERAGE PHOSPHORUS CONCENTRATION IN RAW MUNICIPAL WASTEWATER IS ABOUT 8 MG / I; ABOUT 70 PERCENT OF THE INCOMING PHOSPHORUS NORMALLY IS DISCHARGED WITH SECONDARY TREATMENT PLANT effluentS. IN THIS RESEARCH, THE ROLE OF ADDING DIFFERENT KINDS OF COAGULANTS ON PHOSPHORUS REMOVAL EFFICIENCY OF AN ELECTROCHEMICAL PROCESS WAS INVESTIGATED. THE RESEARCH IS A BENCH SCALE EXPERIMENTAL TYPE USING BATCH SYSTEM FOR ELEC. PROCESS WITH DIRECT CURRENT. SAMPLES WERE COLLECTED FROM AN EXTENDED AERATION effluent. THE USED ELECTRODE WAS STEEL TYPE AND ITS TOTAL EFFECTIVE AREA WAS 336 CM^2. IN EACH RUN 1500 ML OF SAMPLE WAS PLACED IN AN ELECTROLYTIC CELL EQUIPPED WITH MAGNETIC STIRRER. THE RESULTS SHOW THAT PHOSPHORUS REMOVAL EFFICIENCY INCREASES BY INCREASING OF DC AND REACTION TIME. MINIMUM RATE OF CURRENT/PERCENTAGE OF REMOVAL WAS OBTAINED FOR 0.6AMP CURRENT AND UNDER THE SAME CONDITIONS MINIMUM RATE OF REACTION TIME/PERCENTAGE OF REMOVAL WAS PROVIDED IN 15 MIN. IN 6MIN REACTION TIME AND 0.6AMP CURRENT, ADDING POLY ALUMINUM CHLORIDE (PAC) UP TO ABOUT 27 MG/1 COULD IMPROVE THE EFFICIENCY UP TO ABOUT 50%. BUT UNDER THE SAME CONDITION, SIMILAR RESULTS WERE NOT OBSERVED IN 12MIN REACTION TIME. BESIDES, ADDING ALUM OR FERROUS SULFATE SHOWED SIMILAR BEHAVIOR TO PAC. ELECTROCHEMICAL TREATMENT WITHOUT ADDITION OF COAGULANTS AND THEREBY WITHOUT ANY CHANGES ON THE PRIMARY CHARACTERISTICS OF THE SAMPLE CAN REMOVE THE PHOSPHORUS UP TO ABOUT 93%. BUT IN THE CASE OF SUFFICIENT REACTION TIME FOR ELECTROCHEMICAL PROCESS, ADDING COAGULANTS CAN NOT IMPROVE THE EFFICIENCY AND IN COMPARISON TO A CHEMICAL PRECIPITATION ALONE, THE USE OF ELECTROCHEMICAL TREATMENT CAN NOT REDUCE THE REQUIRED DOSES OF COAGULANTS IN SHORT REACTION TIME.

Bioremediation of metal pollutants from industrial wastewater using metal resistant bacteria is a very important aspect of environmental biotechnology. In this study, three species of Pseudomonas aeruginosa were isolated from active sludge of a food factory in the city of Kerman. The bacterial identity was determined by various biochemical tests. Among them, isolate number one could grow on Muller-Hinton agar medium containing 6mM cadmium ion (Cd2+) and was therefore selected for further study. The isolates were subjected to mutation by two mutagenic agents (Acridine Orange and Acriflavine) using gradient plate and SIC techniques. The Minimum Inhibitory Concentration of Cd2+ for the isolate one after mutation was increased to 7mM. Removal of Cd2+using mutated and wild type strains of this bacterium was carried out at different time intervals (10-300 minutes). It was observed that within 60 minutes, 94.7% of cadmium was removed in 30mg/L of Cd2+ solution. However, with 60mg/L Cd2+ solution, only 53.58% and 38.68% Cd2+ removed were achieved by mutated and wild type bacteria, respectively. The equilibrium data was fitted by Langmuir isotherm equation and the related parameters for Cd2+ were derived. Based on the data obtained in this study, it can be concluded that biomass of this bacterium can be used for bioremediation of cadmium from industrial waste processing plants with high efficiency.

The effect of organic loading rate (OLR) provided by hydraulic retention time (HRT) and influent chemical oxygen demand (CODin) on the performance of an up-flow anaerobic sludge fixed film (UASFF) bioreactor treating palm oil mill effluent (POME) was studied. Anaerobic digestion of POME was modeled and analyzed with two variables i.e. HRT and CODin. Experiments were conducted based on a general factorial design and analyzed using response surface methodology (RSM). The region of exploration for digestion of POME was taken as the area enclosed by HRT (1 to 6 days) and CODin (5260 to 34725 mg/L) boundaries. A simultaneous increase of the variables determined a decrease of COD removal efficiency, SRT and SRF and an increase of COD removal rate, VFA/Alk., CO2 fraction in biogas, methane production rate. The best COD removal rate for POME treatment in an anaerobic hybrid reactor has obtained at an OLR of 17.6 g COD/l.d while it was at 26.21 g COD/l.d (Corresponds to CODin of 26210 mg COD/l and HRT of 1 day) in the present study. Minimum and maximum SRT values obtained were 16 and 1904 days at OLR of 34.73 and 0.88 g COD/l.d, respectively. The present study provides valuable information about interrelations of quality and process parameters at different values of the operating variables.

In this research, sludge characterization and rates of mineralization was evaluated in different sizes of rainbow trout (Oncorhynchus mykiss) in the culture systems. Four weight groups of fish (20±3; 50±5; 100±9; 200±10 gr) in triplicates were introduced and cultured in the experimental units (200 liter tanks) for a three day period. The fish were fed with a commercial dry feed pellete (Faradaneh Co.). The rates of mineralization due to the effect of natural flora (microorganisms) of bacteria on the produced sludge, was detected. In this respect, the fish captured and remainder sludge and the rate of macro and microelements recorded in all the treatments during a 7 day period. Concentration of TAN (Total Ammonia Nitrogen) and NO3-, shwoed significant differences among all treatments within initial day until the third day (p<0.05). Concentration of total phosphorous (TP) increased and showed significant differences among treatments after the first stage of the experiment (three days) (p<0.05). EC and total hardness showed significant differences among the treatments after the first stage of the experiment as well (p<0.05). It was concluded that, bacterial mineralization of sludge and organic matter had larger effect at the first three days, in comparison with after harvest of fishes as well.