Extracellular polymeric substances and dewaterability of waste activated sludge during anaerobic digestion.

Anaerobic digestion of waste activated sludge was conducted to gain insight into the mechanisms underlying change in sludge dewaterability during its anaerobic digestion. Unexpectedly, the results indicated that sludge dewatering properties measured by capillary suction time only deteriorated after 10 days of anaerobic digestion, after which dewaterability recovered and remained stable. The loosely bound extracellular polymeric substance (LB-EPS) content increased three-fold after 20 days of anaerobic digestion, and did not change significantly during the remaining 30 days.

Effects of microwave irradiation on dewaterability and extracellular polymeric substances of waste activated sludge.

The effects of microwave irradiation on filterability and dewaterability of waste activated sludge measured by capillary suction time (CST) and dry solids in sludge cake were investigated. The results showed that the optimum irradiation time improved filterability, but that further increase of the time was detrimental. Dewaterability was enhanced significantly and increased with microwave time.

Investigation of extracellular polymer substances (EPS) and physicochemical properties of activated sludge from different municipal and industrial wastewater treatment plants.

This paper examines the chemical constituents of extracellular polymeric substances (EPS) and physicochemical properties of eight different sludge flocs from seven full-scale wastewater treatment plants. The physicochemical properties included floc properties (floc size, turbidity and effluent suspended solids (ESS) content of the supernatant), sludge volume index, capillary suction time and specific resistance to filtration. The relationships between the chemical constituents of EPS and the flocculation, settleability and dewaterability of sludge flocs were also assessed.

Effect of potassium ferrate on disintegration of waste activated sludge (WAS).

The activated sludge process of wastewater treatment results in the generation of a considerable amount of excess activated sludge. Increased attention has been given to minimization of waste activated sludge recently. This paper investigated the effect of potassium ferrate oxidation pretreatment on the disintegration of the waste activated sludge at various dosages of potassium ferrate.

Effects of potassium ferrate on extracellular polymeric substances (EPS) and physicochemical properties of excess activated sludge.

The activated sludge process of wastewater results in the generation of a considerable amount of excess activated sludge. In many wastewater treatment plants, the bottleneck of the sludge handling system is the dewatering operation. This paper investigated the effect of potassium ferrate pretreatment on the physicochemical properties of the excess activated sludge at various dosages of potassium ferrate.

Comparative investigation of parameters for determining the dewaterability of activated sludge.

This paper compared four parameters evaluating the dewaterability of sludge--capillary suction time (CST), specific resistance to filtration (SRF), bound water content, and dry solids content in the centrifuged sludge cake of the different sludge flocs from seven full-scale wastewater treatment plants. The dry solids content correlated with the normalized CST (R2 = 0.7112, p = 0.

Influences of influent carbon source on extracellular polymeric substances (EPS) and physicochemical properties of activated sludge.

It is necessary to understand the bioflocculation, settling and dewatering characteristics in the activated sludge process in order to establish more efficient operational strategies. The influences of carbon source on the extracellular polymeric substances (EPS) and flocculation, settling and dewatering properties of the activated sludge were investigated. Laboratory-scale completely mixed activated sludge processes were used to grow the activated sludge with different carbon sources of starch, glucose and sodium acetate.

Effect of C/N ratio on extracellular polymeric substances (EPS) and physicochemical properties of activated sludge flocs.

The influences of C/N ratio on the extracellular polymeric substances (EPS) and physicochemical properties of the activated sludge flocs were investigated using laboratory-scale sequencing batch reactors (SBRs). Flocs sizes decreased when C/N ratio increased from 20 to 100 and decreased from 20 to 4. The amount of total EPS, TB-EPS, and the carbohydrate and protein contents in TB-EPS were independent of the C/N ratio.

Biosorption and biodegradation of pentachlorophenol (PCP) in an upflow anaerobic sludge blanket (UASB) reactor.

In order to understand the fate of PCP in upflow anaerobic sludge blanket reactor (UASB) more completely, the sorption and biodegradation of pentachlorophenol (PCP) by anaerobic sludge granules were investigated. The anaerobic granular sludge degrading PCP was formed in UASB reactor, which was seeded with anaerobic sludge acclimated by chlorophenols. At the hydraulic retention time (HRT) of 20-22 h, and PCP loading rate of 200-220 mg l(-1) d(-1), UASB reactor exhibited good performance in treating wastewater which containing 170-180 mg l(-1) PCP and the PCP removal rate of 99.

Advanced start-up of anaerobic attached film expanded bed reactor by pre-aeration of biofilm carrier.

The start-up and performance of the anaerobic attached film expanded bed (AAFEB) reactor with pre-aeration of carrier were investigated. The carriers of the reactors had been aerated for 10 days before they were put into the AAFEB reactors. The results indicated that the reactors advance the start-up by 15 days, and maintain higher efficiency when they were subjected to organic and hydraulic loading shock, but during steady-state operation, the reactors did not show better performance than the control reactors without pre-aeration of carrier.

[The use of chemical uncoupler to reduce sludge yield in activated sludge process].

To determine whether chemical additions can be used to reduce sludge production in biological wastewater treatment, 3,3',4',5-tetrachlorosalicylanilide (TCS), served as a metabolic uncoupler was added to activated sludge cultures. The batch tests have confirmed that TCS is an effective chemical uncoupler in reducing the sludge yield when its concentration is higher than 1.0 mg/L.

Acclimation of anaerobic sludge degrading chlorophenols and the biodegradation kinetics during acclimation period.

The acclimation of sludge from Hangzhou citrate factory and Hangzhou municipal wastewater treatment plant for degradation dechlorination of chlorophenols (CPs) compounds, and its biodegradation kinetics were studied in batch process with or without addition of sucrose. Three monochlorophenols (2-CP; 3-CP; 4-CP) and pentachlorophenol (PCP) were concurrently fed to different bioreactors. The parameters that were monitored included biogas production, biogas composition and chemical oxygen demand (COD).