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Enhancement the conditioning of waste activated sludge through a sequence of freeze/thaw-electro-Fenton process

Shahheidar N., Jorfi S., Takdastan A., Jaafarzadeh N., Ahmadi M.

Polish Journal of Chemical Technology

2018

Vol. 20, nr 1

47--53

Sludge conditioning is an important stage in sludge management. In the present study, a sequence of freeze/thaw-electro-Fenton process was designed and specific resistance filtration (SRF) was monitored during sludge conditioning as an important factor in sludge dewaterability. Furthermore, protein and polysaccharide concentrations were measured during the experiments. Results showed that the lowest SRF value contributed to −10°C in freezing process which showed a reducing trend by decreasing solution pH. In addition, results revealed that solution pH less than 3 caused a significant improvement in sludge dewatering; so the lowest SRF has been registered at pH = 2. By increasing current intensity from 0.5 to 1A, SRF values were reduced and then followed by an enhancement with increasing current intensity to 3.2 A. The lowest SRF value (6.1 × 104 m/kg) was obtained at H2O2 = 30 mg/L which was the best conditions for sludge dewatering.

Adsorption of Cr(VI) by Natural Clinoptilolite Zeolite from Aqueous Solutions: Isotherms and Kinetics

Jorfi S., Ahmadi M. J., Pourfadakari S., Jaafarzadeh N., Soltani R. D. C., Akbari H.

Polish Journal of Chemical Technology

2017

Vol. 19, nr 3

106--114

The main aim of this study was to evaluate the efficiency of natural zeolite for Cr(VI) removal from aqueous solutions. Following simple modification of adsorbent, the effect of operational parameters including pH (2–10), adsorbent dosage (2–20 g/L), contact time (5–150 min) and Cr(VI) concentration (10–50 mg/L) were studied according to one-factor-at-a-time procedure. The maximum Cr(VI) removal of 99.53% was obtained at initial pH of 2, contact time of 30 min, adsorbent dosage of 8 g/L and initial chromium concentration of 10 mg/L. The Freundlich isotherm was best fitted with experimental data (R2 = 0.951). Also, type 1pseudo second order kinetic model showed the most correlation (R2 = 1) with the experimental data. According to obtained results, it can be concluded that the application of clay-like adsorbents such as natural clinoptilolite zeolite can be considered as an efficient alternative for final treatment of effluents containing Cr(VI).