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Powdered-acid-activated-neutralized red mud (Aan-RM), the chemico-physically modified product of red mud, was for the first time employed with hydroxypropyl methylcellulose and powdered straw as the main ingredients for granular Aan-RM production for phosphate removal. In order to better understand the phosphate adsorption characteristics of granular Aan-RM, the influence of operational parameters on the performance of granular Aan-RM and the possible adsorption mechanisms involved were investigated. The results demonstrated that the adsorbent dosage, adsorption temperature, and initial solution pH influenced the adsorption performance of granular Aan-RM significantly. The maximum phosphate adsorption capacity of granular Aan-RM reached 153.227 mg/g with the granular Aan-RM dosage of 3.0 g/L, adsorption temperature of 40 °C, and initial solution pH of 6.0. The whole adsorption process was well described by nth-order kinetic model and Langmuir–Freundlich isotherm. Meanwhile, X-ray photoelectron spectroscopy (XPS) analysis of P 2p peak on granular Aan-RM after phosphate adsorption demonstrated that 79.01 % of the phosphate was adsorbed through precipitation and ion exchange mechanisms with strong chemical bonds, and 20.99 % of the phosphate was adsorbed through surface deposition mechanism with weak chemical bonds.

Acid-activated Bauxsol was applied to treat wastewater with high phosphate concentration in a batch adsorption system in this paper. The effect of acid activation on the change of Bauxsol structure was systematically investigated. The mineralogical inhomogeneity and intensity of Bauxsol decreased after acid activation, and FeCl3·2H2O and Al(OH)3 became the dominant phases of acid-activated Bauxsol adsorption. Moreover, the BET surface area and total pore volume of Bauxsol increased after acid activation. Interaction of initial solution pH and adsorption temperature on phosphate adsorption onto acid-activated Bauxsol was investigated by using response surface methodology with central composite design. The maximum phosphate adsorption capacity of 192.94 mg g(-1) was achieved with an initial solution pH of 4.19 and an adsorption temperature of 52.18 °C, which increased by 7.61 times compared with that of Bauxsol (22.40 mg g(-1)), and was higher than other adsorbents. Furthermore, the desorption studies demonstrated that the acid-activated Bauxsol was successfully regenerated with 0.5 mol L(-1) HCl solution. The adsorption capacity and desorption efficiency of acid-activated Bauxsol maintained at 80.48% and 93.02% in the fifth adsorption-desorption cycle, respectively, suggesting that the acid-activated Bauxsol could be repeatedly used in wastewater treatment with high phosphate concentration.

Degradation of protein and carbohydrate is vital for sludge anaerobic digestion performance. However, few studies focused on degradation properties of protein and carbohydrate. This study investigated detailed degradation properties of sludge protein and carbohydrate in order to gain insight into organics removal during anaerobic digestion. Results showed that carbohydrate was more efficiently degraded than protein and was degraded prior to protein. The final removal efficiencies of carbohydrate and protein were 49.7% and 32.2%, respectively. The first 3 days were a lag phase for protein degradation since rapid carbohydrate degradation in this phase led to repression of protease formation. Kinetics results showed that, after initial lag phase, protein degradation followed the first-order kinetic with rate constants of 0.0197 and 0.0018 d−1 during later rapid degradation phase and slow degradation phase, respectively. Carbohydrate degradation also followed the first-order kinetics with a rate constant of 0.007 d−1 after initial quick degradation phase.

This study aimed at enhancing the bacterial biomass and pigments production in together with pollution removal in photosynthetic bacteria (PSB) wastewater treatment via using different photoperiods. Different light/dark cycles and light/dark cycle frequencies were examined. Results showed that PSB had the highest biomass production, COD removal and biomass yield, and light energy efficiency with light/dark cycle of 2h/1h. The corresponding biomass, COD removal and biomass yield reached 2068mg/L, 90.3%, and 0.38mg-biomass/mg-COD-removal, respectively. PSB showed higher biomass production and biomass yield with higher light/dark cycle frequency. Mechanism analysis showed within a light/dark cycle from 1h/2h to 2h/1h, the carotenoid and bacteriochlorophyll production increased with an increase in light/dark cycle. Moreover, the pigment contents were much higher with lower frequency of 2-4 times/d.

Due to their special properties, people have been increasingly interested in studying applications of nanoscale metal materials in environmental engineering. Literature about the current research on the synthesis, properties, and environmental applications of nanoscale iron-based materials is reviewed and summarized in this article. Different physical and chemical methods used for synthesizing nano-iron-based particles with desired size, structure, and surface properties are described. We also emphasize important properties of nano-iron-based particles, including the density and intrinsic reactivity of surface sites. These properties directly influence the chemical behavior of such particles and, consequently, affect their applications in water and wastewater treatment and in air pollution control. Environmental applications of nano-iron particles are discussed in detail, including removal of chlorinated organics, heavy metals, and inorganics.

Algae bloom in source water causes high chemical consumption and deteriorates water quality in waterworks. This paper studied the ultrasonic removal of Microcystis aeruginosa. The results showed that algae cells could be effectively removed by sonication and gas vesicle collapse was the main mechanism. The ultrasonic algae removal followed the first order reaction with a rate constant of 0.023 min(-1) (80 W, 80 kHz). Higher ultrasound frequency benefited algae removal; the algae removal rate constant was 0.114 min(-1) at 1320 kHz and 0.0224 min(-1) at 20 kHz (80 W). Higher ultrasound power also accelerated algae removal; the algae removal rate constant was 0.023 min(-1) at 80 W and 0.007 min(-1) at 32 W (80 kHz). However, high ultrasound power and long irradiation caused microcystins to increase. 80 W, 80 kHz sonication for 5 min increased the extracellular microcystins concentration from 0.87 microg/L to 3.11 microg/L. Sound frequency had little impact on the microcystins release. The chlorophyll a concentration initially decreased and then stabilized after 5 min of sonication.

This paper investigates the treatment of chromium (Cr) contaminated industrial sludge from a tanning process with ultrasound to enhance the sludge settling ability and dewatering ability. Ultrasound at various frequencies, intensities, and time was tested to optimize the operation. The results show that treatment with 30 kHz, 12 W/L ultrasound for 120 s shortened the sludge settling time from 3 h to 1 h and reduced the supernatant Cr concentration. The ultrasonic treatment also reduced the sludge volume from 4.02 mL/g to 2.58 mL/g and increased the sludge Cr concentration by 2/3. The treated sludge could then be reused in the tanning operation. Proper ultrasonic treatment can significantly reduce the sludge volume and enhance the Cr reuse.

The different coagulation-flocculation behavior of iron(III) and aluminum(III) to coagulate silica particle suspension with four coagulants - FeCl 3 , Fe 2 (SO 4 ) 3 , AlCl 3 , and in our laboratory produced polyaluminum chloride PACl-2.0 - was investigated through studying particle property changes and coagulation efficiency, for example, variations in zeta potential of particles, particle number, average particle diameter, particle size distribution, and residual turbidity of the supernatant water. Influences of flocculation intensity and pH value on the coagulation-flocculation process were also studied. The results suggest that, under the test conditions, among these four coagulants FeCl 3 possesses an obviously stronger ability to form larger flocs and to remove turbidity, on the other hand, PACl-2.0 obviously showed a better charge neutralization ability.

Bauxsol is a chemico-physically modified product of red mud and is a promising material for the removal and recovery of phosphorus from wastewater. In this study, response surface methodology (RSM) and artificial neural network (ANN) were employed to develop prediction models and also to investigate the interactions of independent experimental factors for phosphorus adsorption onto acid-activated Bauxsol. The experimental results indicated that HCl activation was effective to improve the adsorption capacity of Bauxsol. The maximum adsorption capacity of acid-activated Bauxsol was 55.72 mg/g (as P) with HCl concentration of 10.20 mol/L, temperature of 41.00 °C, and time of 5.60 h, which increased by 10.53 and 6.62 times compared with the raw red mud and Bauxsol before acid activation, respectively. The relative importance of HCl concentration in RSM and ANN models was 51.78 and 54.25 %, respectively, which illustrated that HCl concentration played the predominant role on improving the adsorption capacity of Bauxsol. The predictive capability of RSM and ANN models was compared, and the results showed that both models provided excellent predictions with R 2 > 0.93. However, the ANN model showed the superiority over RSM for estimation capability.

This study is aimed at enhancing biomass and pigments production together with pollution removal in photosynthetic bacteria (PSB) wastewater treatment via different light sources. Red, yellow, blue, white LED and incandescent lamp were used. Results showed different light sources had great effects on the PSB. PSB had the highest biomass production, COD removal and biomass yield with red LED. The corresponding biomass, COD removal and biomass yield reached 2580 mg/L, 88.6% and 0.49 mg-biomass/mg-COD-removal, respectively. The hydraulic retention time of wastewater treatment could be shortened to 72 h with red LED. Mechanism analysis showed higher ATP was produced with red LED than others. Light sources could significantly affect the pigments production. The pigments productions were greatly higher with LED than incandescent lamp. Yellow LED had the highest pigments production while red LED produced the highest carotenoid/bacteriochlorophyll ratio. Considering both efficiency and energy cost, red LED was the optimal light source.

This study investigated the feasibility of using photosynthetic bacteria (PSB) to produce biomass and carotenoid while treating wastewater. The effects of light intensity on the biomass, carotenoid and bacteriochlorophyll accumulation in together with pollutant removal were studied. Results showed that it was feasible to use PSB to treat wastewater as well as to produce biomass or carotenoid. 2000 lux was an optimal intensity for biomass production and COD removal, and the corresponding values were 2645 mg/L and 94.7%. 8000 lux was an optimal light intensity for carotenoid production (1.455 mg/L). Mechanism analysis displayed that the greater the bacteriochlorophyll and carotenoid were secreted, the lower the light conversion efficiency turned out to be. The highest light conversion efficiency was achieved at 500 lux; the ATP production, biomass production, and COD removal were the highest at 2000 lux, but the bacteriochlorophyll and carotenoid content were the lowest at 2000 lux.

The present study is aimed at enhanced cell production in together with pollution removal in photosynthetic bacteria wastewater treatment through low-strength ultrasound stimulation. The ultrasound strength was 0.3 W/cm 2 with 40 kHz frequency. Results showed 1–10 min sonication significantly improved the cell production. The optimal sonication time was 2 min. When the irradiation period was over 10 min, a strong mechanical damage occurred. These phenomena could be explained by the changes of PSB dehydrogenase activity. Sonication stimulated the initial dehydrogenase activity; moderate sonication increased the cell activity while too-long sonication led to quick enzyme activity decrease. The optimal sonication strategy was 1 min at the 0th hour and 1 min at the 27th hour. The corresponding cell production and cell yield increased by 110% and 93% respectively, and the COD removal reached 98%. The cost of low-strength ultrasound was only 1% of the incremental sales value of cells.

The behavior of sludge solubilization using high-pressure homogenization (HPH) treatment was examined by investigating the sludge solid reduction and organics solubilization. The sludge volatile suspended solids (VSS) decreased from 10.58 to 6.67 g/L for the sludge sample with a total solids content (TS) of 1.49% after HPH treatment at a homogenization pressure of 80 MPa with four homogenization cycles; total suspended solids (TSS) correspondingly decreased from 14.26 to 9.91 g/L. About 86.15% of the TSS reduction was attributed to the VSS reduction. The increase of homogenization pressure from 20 to 80 MPa or homogenization cycle number from 1 to 4 was favorable to the sludge organics solubilization, and the protein and polysaccharide solubilization linearly increased with the soluble chemical oxygen demand (SCOD) solubilization. More proteins were solubilized than polysaccharides. The linear relationship between SCOD solubilization and VSS reduction had no significant change under different homogenization pressures, homogenization cycles and sludge solid contents. The SCOD of 1.65 g/L was solubilized for the VSS reduction of 1.00 g/L for the three experimental sludge samples with a TS of 1.00, 1.49 and 2.48% under all HPH operating conditions. The energy efficiency results showed that the HPH treatment at a homogenization pressure of 30 MPa with a single homogenization cycle for the sludge sample with a TS of 2.48% was the most energy efficient.

Alkaline pretreatment combined with high pressure homogenization (HPH) was applied to promote sewage sludge disintegration. For sewage sludge with a total solid content of 1.82%, sludge disintegration degree (DD(COD)) with combined treatment was higher than the sum of DD(COD) with single alkaline and single HPH treatment. NaOH dosage ⩽0.04mol/L, homogenization pressure ⩽60MPa and a single homogenization cycle were the suitable conditions for combined sludge treatment. The combined sludge treatment showed a maximum DD(COD) of 59.26%. By regression analysis, the combined sludge disintegration model was established as 11-DD(COD)=0.713C(0.334)P(0.234)N(0.119), showing that the effect of operating parameters on sludge disintegration followed the order: NaOH dosage>homogenization pressure>number of homogenization cycle. The energy efficiency with combined sludge treatment significantly increased compared with that with single HPH treatment, and the high energy efficiency was achieved at low homogenization pressure with a single homogenization cycle.

To improve anaerobic sludge digestion efficiency, the effects of high-pressure homogenization (HPH) conditions on the anaerobic sludge digestion were investigated. The VS and TCOD were significantly removed with the anaerobic digestion, and the VS removal and TCOD removal increased with increasing the homogenization pressure and homogenization cycle number; correspondingly, the accumulative biogas production also increased with increasing the homogenization pressure and homogenization cycle number. The optimal homogenization pressure was 50 MPa for one homogenization cycle and 40 MPa for two homogenization cycles. The SCOD of the sludge supernatant significantly increased with increasing the homogenization pressure and homogenization cycle number due to the sludge disintegration. The relationship between the biogas production and the sludge disintegration showed that the accumulative biogas and methane production were mainly enhanced by the sludge disintegration, which accelerated the anaerobic digestion process and improved the methane content in the biogas.

This paper used a novel technology, BAF-SCAD, for the advanced nitrogen removal of wastewater after con. BAF stood for biological aerated filter and SCAD meant sulfur-ceramic autotrophic denitrification. The experimental results show that the BAF-SCAD system was successfully started after 2.5 months' starting up. With a NaHCO 3 dosage of 1 g/L, the BAF-SCAD system effectively removed the pollutants. Excellent nitrogen removal was achieved by nitrification in the BAF and denitrification in the SCAD. When the concentrations of NH 3 -N, NO 3 -N, TN in the influent were 10–20mg/L, 8–16mg/L, 25–30mg/L respectively, the concentrations of NH 3 -N and NO 3 -N in the effluent were below 1mg/L and the TN was 1–3 mg/L. The removal efficiency of NH 3 -N was above 95% and the removal efficiency of TN was above 90%. The COD removal efficiency of BAF was between 20%–30%, while COD in the effluent of SCAD increased slightly. The results showed a promising new approach for the biological denitrification of the secondary effluent of municipal wastewater treatment plant under low carbon source.

The treatment of low temperature and low turbidity water is a worldwide challenge. Direct filtration with micro-flocculation is a simple and economic method to purity such a source water. This paper investigated the performance of this method to treat a low-temperature and low-turbidity reservoir water in pilot scale. The filter used was a rapid sand filter with quartz sand-Anthracite dual-media, and the coagulant was the polymerization aluminum (PAC). It was found that dual-media was superior for organic removal. The CODMn of effluent was less than 3mg/L, the UV254 removal rate was greater than 50%, and the effluent turbidity was less than 0.5NTU. The suggested PAC dosage was 16mg / L. When the filtration rate was 4m/h, the filter cycle would be 12h.

The tidal-flow constructed wetland is a new type of constructed wetland proposed by the University of Birmingham, U.K. The principal of the wetland takes advantage of the rhythmical movement of wastewater and air which accelerates the alternation of aerobic and anaerobic to realize and enhance pollutant removal. This study focused on two aspects, the different operation performances for treating pollutants at a low temperature in winter between tidal-flow and traditional continuous-flow constructed wetlands, and the influences of treatment efficiency under different operating circumstances. The results showed that, under 0.2m3/m2/dhydraulic load, the removal rates of the three-cycles/d tidal flow constructed wetland for NH4+-N, COD and PO43--P could reach 48.57%, 68.96% and 29.02% respectively, which were about 30%, 20% and 20% higher than these in continuous flow wetlands, correspondingly.

Previous study showed that sonication was effective to reduce waste activated sludge (WAS) using artificial wastewater. This paper confirms the viability and evaluates the performance of this method in practical wastewater treatment using urban sewage without temperature control. The results showed that sonication significantly lowered the WAS and biomass synthesis, and greatly enhanced the mineralization of sewage organics. The optimal specific energy for sludge lysis was 20.0 kWh/kgDS. Further energy-increase had little benefit on WAS reduction. When the specific energy was 20.0 kWh/kgDS and the sludge recycle ratio was 0.007, the WAS decreased by 54%, the biomass synthesis abated by 59%, and the sewage mineralization ratio increased from 31% to 58%. The effluent COD and nitrogen were stable but phosphorus was higher than that of the control bioreactor. The COD removal was lower but the WAS reduction was higher for urban sewage than for artificial wastewater. The accumulation pattern of heavy metals in sludge was greatly alternated by the sonication-cryptic growth; and different metals behaved differently. The sludge Ni concentration increased by 141% while As decreased by 53%.

A major limitation of land application of compost is the potential heavy metal pollution, and lead (Pb) has been recognized as one of the most hazardous heavy metal. To reduce the hazards of Pb to the compost application, composting of Pb- polluted wastes by inoculating white-rot fungi was investigated. The parallel waste composting with no inoculants was performed as control. The form distribution and transformation of Pb during composting were discussed. Results showed that the active Pb ion was transformed into the inactive phase during composting. The soluble-exchangeable Pb with high toxicity in composting with white-rot fungi was reduced to 0 mg/kg dry weight compost at day 50, while that of the control only achieved 100.5 mg/kg till day 60. The higher content of organic-bound Pb (121.0 mg/kg) and residual Pb (141.9 mg/kg) with low toxicity was found after 60-day composting with white-rot fungi, compared to those in control. Meanwhile, the higher microbial biomass was observed in composting with white-rot fungi, and Pb concentrations correlated to the microbial biomass. All the results indicated that the method of composting with white-rot fungi reduced the transfer and bioavailability of Pb in compost so as to alleviate the potential stress of metal, and also improved the microbial growth.

The waste of domestic water causes the waste of water resource and the increasing sanitary sewage generated. To make the necessary reductions in the volumes of water used and wastewater generated, the water-saving study of urban domestic water based on the optimization design of flow pipe was performed at laboratory scale. Dynamics of the two-dimensional flow in siphonic water closets (WC), such as the flow regimes, velocity field and pressure field in the flow pipe, was investigated using a computational fluid dynamics (CFD) model and particle image velocimetry (PIV). The pressure and velocity in the shrinking nozzle of pipe were compared by CFD under different pipe shape. Result indicated that the pressure in pipe in the full-siphon stage and the siphon-generated time are of the most importance for the performance of WC. It was confirmed that the redesign of the shrinking nozzle of the pipe led to the reduction of water consumption. These numerical analyses and analog simulations presented the optimal shape design of flow pipe, which reduced the water consumption from 6 L to 4.5 L. The decrease of the water used in WC reduced the sanitary sewage generated. All the results and the research methods are expected to offer some reference for improving the sustainability of water based sanitation systems and developing a friendly sustainable domestic-water-saving technology. The method reported in this paper has profound environmental effect.

Source water eutrophication has caused serious problems in drinking water supplies, with enhanced coagulation widely used to remove the resulting algae. This paper investigates the use of sonication to improve the removal by coagulation of Microcystis aeruginosa, a common species of toxic algae. The results show that sonication significantly enhances the reduction of algae cells, solution UV254, and chlorophyll a without increasing the concentration of aqueous microcystins. The main mechanism involved the destruction during ultrasonic irradiation of gas vacuoles inside algae cells that acted as 'nuclei' for acoustic cavitation and collapse during the "bubble crush" period, resulting in the settlement of cyanobacteria. Coagulation efficiency depended strongly on the coagulant dose and sonication conditions. When the coagulant dose was 0.5mg/l, 5s of ultrasonic irradiation increased algae removal efficiency from 35% to 67%. As further sonication enhanced the coagulation efficiency only slightly due to better mixing, optimal sonication time was 5s. The most effective sonication intensity was 47.2W/cm2, and the highest removal ratio of M. aeruginosa was 93.5% by the sonication-coagulation method. Experiments with reservoir water showed that this method could be successfully applied to natural water containing multiple species of algae.

This paper improves the energy efficiency for sludge treatment using ultrasound. The sludge organic content, solid concentration, ultrasonic intensity, and time were optimized. A new index, kWh/kg SCOD-increase, was used to evaluate the energy efficiency that covers both sludge characteristics and lysis effectiveness. The results showed that the energy efficiency of sludge sonication was in the range of 102–347 kWh/kg SCOD-increase. Higher VS/TS ratio gave higher energy efficiency. Optimal solid concentration (TS) was found to be 20 g/L; low TS (5.0 g/L) consumed 137% more energy; while higher TS might assimilate the sound energy and decrease the efficiency. The cavitation threshold for sludge was 20–30 W/cm 2 , below which no sludge lysis was observed. The lowest effective sound intensity (31.4 W/cm 2 ) was best and saved 20–35% energy compared to higher intensities. The initial first minutes of sonication were most effective; hence intensive-short treatment was preferred.

Algae bloom in source water has caused serious problems in drinking water supplies, and conventional methods for its treatment have achieved only limited success. This paper reports a new technology, ultrasound assisted coagulation, for effective removal of algae cells from the source water in water treatment works. The results showed that ultrasonic pretreatment significantly enhanced the removal efficiency of algae cells. Ultrasonic irradiation for 5 s increased the algae removal efficiency by more than 20% when the coagulant dose was 0.4-0.8 mg/L. To achieve the same algae removal ratio of 90%, sonication for 5 s reduced the coagulant dose by 2/3. The optimal sonication parameters were determined as follows: sonication time of 1 s, ultrasonic power of 48 W, and solution pH of 8-9. The sound frequency had little impact on the algal removal efficiency. Ultrasonic pretreatment also significantly reduced the sample turbidity.

The aim of this work was to study the effect of ultra sound treatment on the solid content of sludge and biological activity, and the increase in the soluble chemical oxygen demand (SCOD), proteins and nucleic acids concentrations during sonication. The results showed that sonication effectively degraded and inactivated the sludge. The sludge disintegration and cell lysis occurred continuously while sludge inactivation mainly occurred in the second stage (10-30 min) during sonication. The SCOD, supernatant proteins and nucleic acids concentrations, and sludge mass reduction and inactivation degrees increased with the sonication time and power density increases. Higher energy ultrasound was more efficient than lower energy ultrasound for the sludge treatment.

Excessive cyanobacterial growth in eutrophic water sources has been a serious environmental problem, and both sight preservation and drinking water production demand control of cyanobacterial growth in water. Ultrasonic treatment was reported to effectively inhibit cyanobacterial growth through vesicle collapsing and cell fracturing, but little was known about the change of cyanobacterial photosynthesis during sonication. This paper examined the ultrasonic inhibition of Microcystis aeruginosa cell growth and extracellular microcystins release, and the instant ultrasonic decreases of antenna complexes like cyanobacterial chlorophyll a and phycocyanins (PC), and the oxygen evolution rate. The results showed that sonication effectively damaged antenna complexes, slowed down the photo-activity, which significantly inhibited the cell growth and microcystins formation and release.

Aluminium ions hydrolyse and polymerise into different species in water. Main aluminium species in aluminium coagulant solutions are monomeric Al species (Al1) and polymeric Al species Al13O4(OH)24(7+) (Al13). The aluminium species distribution in coagulant solutions can be influenced by many parameters. This paper studies influences of concentrations of total aluminium species (Al(t)) and other species--OH-, polysilicic acid and ferric species, which were added in aluminium coagulant solutions, on the aluminium species distribution through 27Al nuclear magnetic resonance (NMR) analysis. Results show that only Al1 and no Al13 exist in coagulant solutions at higher Al(t) concentrations (over 1 mol l(-1)), while both species exist at lower Al(t) concentrations (0.1 mol l(-1)). The increase of OH/Al value (molar ratio) increases the concentration of Al13 in coagulant solutions, while the addition of polysilicic acid and ferric species decreases the concentration of Al13.

Gravitational thickening is the prevailing method to reduce bio-sludge volume though the process is slow and usually requires addition of polyelectrolyte(s). This paper investigated the potential benefits of sonication on enhancing the bio-sludge gravitational thickening with very low energy dose, thereby called “weak ultrasound”. Results showed that weak sonication significantly changed the bio-sludge settleability and the main mechanism was release of the loosely bound extracellular polymeric substances. The changes were strongly influenced by power density and sonication duration. Low frequency was better but the difference was insignificant. Weak sonication (

The indigenous mixed inocula were cultured and enriched from the thickened waste sewage sludge for heavy metal bioleaching. The mixed inocula were then used for bioleaching, and 2 g/L sulphur was added. The influences of FeSO4?7H2O dosage on heavy metals (Zn, Cu, Pb and Cd) and nutrients (nitrogen and phosphorus) bioleaching were investigated. Results show that the addition of FeSO4?7H2O accelerates the bioleaching process. With the FeSO4?7H2O addition, pH of the sludge decreases and the Oxidation Reduction Potential (ORP) increases more rapidly. The presence of FeSO4?7H2O obviously increases the solubilisation of Zn, Cu and Cd, but has insignificant impact on the Pb solubilisation. FeSO4?7H2O also changes the nitrogen loss and the phosphorus loss. The suitable FeSO4?7H2O dosage is 5?10 g/L; higher dosages cannot accelerate the heavy metal bioleaching more. With the addition of 10 g/L FeSO4?7H2O and 2 g/L sulphur powder, 81.4% of Zn, 81.1% of Cu, 67.6% of Pb and 56.6% of Cd are solubilised from the sludge after 15-day bioleaching at 28?C and an agitating speed of 180 r/min.

The management of excess activated sludge imposes great cost on wastewater treatment plants and represents significant technical challenges. This paper investigates a new technology, sonication and cryptic growth, to reduce the amount of excess sludge from the wastewater treatment system. Subsequent Biological Reactors (SBRs) were used for the study. The results show that the amount of excess sludge could be reduced by 58.8%. The optimal sludge sonication ratio was 1/7, the ultrasonic intensity was 1.6 W/mL, the irradiation time was 15 min and the ultrasonic frequency was 25 kHz. The SBR sludge characteristics, settlability, activity, size and organic content, were stable. The effluent Chemical Oxygen Demand (COD) and Total Nitrogen (TN) concentrations were stable. However, increase in phosphorus concentration in the effluent was observed.

Biotransformation of lignin is related to the biomass utilisation of agricultural wastes. Ligninolytic enzyme from Phanerochaete chrysosporium plays an important role in biodegrading lignin and is specially concerned by researchers. The aim of the study is to optimise the conditions for producing ligninolytic enzymes in solid-state fermentation, and to biotransform the rice straw for the biomass utilisation. The effects of five factors on enzyme activity in state-solid medium were studied using orthogonal experiments, which were expected to offer reference for condition design of enzyme production in solid-state fermentation. The results indicated that the optimal condition for enzyme production by P. chrysosporium during solid-state fermentation could be realised when fungi were domesticated for 8 days, 0.8% fungi suspension (weight ratio) inoculated, temperature kept at 37?C, water content of the solid substrate maintained by 85% and 0.3% Tween80 added, respectively. Also, it was found that the temperature and water content were the foremost influencing factors for the ligninolytic enzyme production of P. chrysosporium during solid-state fermentation. The lignocellulose of rice straw was reduced significantly. The structures of the untreated straw and the straw degraded under the optimal fermentation condition were analysed through ultraviolet spectroscopy and infrared spectroscopy. It could be observed that long-bond and difficult-to-biodegrade hydrocarbons of giant molecule were degraded into short-bond hydrocarbons of small molecule, which could be easily biodegraded.

Low-frequency and high-intensity ultrasonic treatment of biosolid is a good method for biosolid disintegration. So, as a pre-treatment method of anaerobic digestion, it may replace the hydrolysis. Thus, we studied the effect of ultrasonic disintegration of biosolid at different ultrasonic power densities. Results showed that the Soluble Chemical Oxygen Demand (SCOD), Total Nitrogen (TN), Total Phosphorus (TP), supernatant protein, polysaccharide and Deoxyribonucleic Acid (DNA) concentrations and biosolid mass reduction increased with the increase of sonication time and energy density. Ultrasonic treatment at 1.6 W/m for 30 min when the degree of biosolid disintegration (DDCOD) was 49.29% increased the SCOD, TN, TP, supernatant protein, polysaccharide and DNA concentrations by 3285, 150.13, 68.50, 1488.85, 531.66 and 123.35 mg/L, respectively, indicating that ultrasonic treatment can effectively disintegrate the biosolid. Higher energy ultrasound was more efficient than lower energy ultrasound for biosolid treatment.