[Survey of activated sludge process performance in treatment of agghala industrial town waste water in Golestan Province in 2007]

One of environmental outcomes in industrial towns is developing environmental pollution such as production of industrial wastewaters. These industrial wastewaters should be appropriately treated before entering to receiving waters. However we can't solve environmental anxieties by establishing of wastewater treatment plants alone; but permanent and regular assessment of these treatment plants performance is necessary for achieving environmental standards. Thus, this research has been done in order to investigation of activated sludge performance in wastewater treatment of Agghala industrial town in Golestan province. This cross-sectional study implemented in sewage treatment plant laboratory of Agghala industrial town in Golestan within 12 months at 2007. Chemical Oxygen Demand [COD] parameter determined twice in week, But Biochemical Oxygen Demand [BOD] test accomplished weekly. pH measured by pH meter daily. Experiment of total suspended solids [TSS] and total dissolved solids [TDS] carried out every 10 days. All tests accomplished according to standard method for water and waste water examination [2005]. Then data analyzed using excel 2007. The average of BOD, COD and TSS in influent was 11196.17, 1854.58, 1232.25 mg/L respectively.Maximum influent organic loading rate was related to Shahrivar and Mehr months. The total average of removal efficiency for BOD, COD and TSS was calculated 99.66, 98.2, and 97.6% respectively. Quality of this treatment plant effluent was according to effluent disposal standards all over year. In sum, efficiency of this treatment plant [activated sludge system] was very good in influent pollutant removing. However occasionally effluent was not adapted with environmental standards but these deficiencies is solvable by accurate management and supervision on flow rate and influent organic loading rate easily

Effect of hydrophilic and hydrophobic organic matter on amoxicillin and cephalexin residuals rejection from water by nanofiltration

Antibiotics such as amoxicillin and cephalexin are a group of pharmaceutical compounds in human medicine practice that have been entered in water bodies. Presence of these compounds in the environment has raised concerns regarding the toxicity to aquatic organisms and the emergence of strains of antibiotic-resistant bacteria. Removal of these substances before entering the aquatic environment as well as water reuse plant is very important. The objective of this investigation was to evaluate the impact of hydrophilic and hydrophobic fractions of Natural Organic Matter [NOM] on the removal efficiency of cephalexin and amoxicillin, by using two different commercially available composite NF membranes [TFC-SR2 and TFC-SR3]. In addition, the effect of NOM fractions on retention mechanism and permeates flux behavior was studied. Amoxicillin and cephalexin were used as models of antibiotics; alginate and humic acid were used as models of hydrophilic and hydrophobic fractions of NOM, respectively. It was observed that the rejection and permeate flux of amoxicillin and cephalexin were influenced by the membrane characteristics and properties of NOM. The results showed that as the alginate proportion was increased, the rejection improved. The permeate flux decreased with increasing alginate ratio. It was observed that the rejections of amoxicillin and cephalexin in TFC-SR2 were >97.3% and >95.8% in all experiments, respectively. In TFC-SR3, the rejection percentage were [95.9%-100%] and [86.1%-96.3%], respectively. Alginate and humic acid had synergistic effect on flux decline. In other words, increasing alginate concentration increased the rate and extent of flux reduction

[Study of natural organic matter characteristics and fractions in surface water resources of Tehran]

Natural organic matters [NOMs] are abundant in natural water resources and in many ways may affect the unit processes in water treatment. Although NOMs are considered harmless but they have been recognized as disinfection by-products [DBPs] precursors during the chlorination process. Formation of DBPs highly depends on the composition and concentration of NOMs. The objective of this study was to determine natural organic matter and its fractions concentrations in the surface water sources of Tehran. Water sampling was conducted monthly between May to July in three rivers of Lar, Jajrood and Karaj, as the main drinking water supplying sources in Tehran. Quantitative parameters of pH, EC, UV254 and DOC were studied based on standard methods. The XAD-7 resin method was used for fractionation of NOMs. Results showed that NOM concentrations in Lar, Jajrood and Karaj rivers were 8.53, 12.9 and 11.3 mg/L, respectively. The HPO [hydrophobic] fraction was predominant compared to the HPI [hydrophilic] fraction in water samples. The mean of total percent of HPO and HPI fractions were about 57% and 43%, respectively. Since the hydrophobic NOM fraction exhibits higher trihalomethane formation potential [THMFP] than hydrophilic part, Tehran water chlorination exhibits higher THMFP than haloacetic acid formation potential [HAAFP]. The information obtained from this study may be further employed in the design of the control techniques and management strategies for the water treatment plant, especially for DBPs reduction

Retention of humic acid from water by nanofiltration membrane and influence of solution chemistry on membrane performance

The objectives of this research were to investigate the rejection efficiency of salt and hydrophobic fraction of natural organic matter, to study the flux decline behavior with a spiral wound nanofiltration membrane, and also to survey the influence of water chemistry on membrane performance. Experiments were conducted using a cross flow pilot-scale membrane unit with a full circulation mode. Humic acid was used as hydrophobic organic matter and NaCl as background electrolyte. Results showed that flux reduction increased with increasing ionic strength and humic acid concentration, and with lower pH. The rejection efficiency of organic and salt decreased with the decrease in pH and increase in ionic strength, because of osmotic pressure increase, leading to permeate flux decline and decrease in salt rejection. In addition, the improved salt rejection was likely due to Donnan exclusion by humic material close to membrane surfaces. The average rejection efficiency of humic acid and salt ranged between 91.2%-95.25% and 63.6%-80%, respectively. Dissolved organic carbon concentration was less than 0.57mg/L in permeate for all experiments. With increasing organic concentration, the charge of the membrane surface has become more negative due to the adsorption of organic foulants on the membrane surface, and thus increased the electrostatic repulsion. However, the increasing surface charge had the potential to result in a larger molecular weight cut-off of a fouled membrane due to membrane swelling which can lead to lower rejection solutes. Therefore, results of this study indicated that membrane fouling may significantly affect the rejection of organic and ion solute