Proteomic analysis reveals mechanisms of mixed wastewater with different N/P ratios affecting the growth and biochemical characteristics of Chlorella pyrenoidosa.

Effects of different nutrient ratios on the biochemical compositions of microalgae and the changes were rarely studied at the molecular level. In this study, the impacts of various nitrogen to phosphorus (N/P) ratios on growing of C. pyrenoidosa, as well as biochemical compositions and the metabolic regulation mechanism in mixed sewage, were investigated. The results suggested that 18 was optimal N/P ratio, while the dry weight (1.0 g/L), chlorophyll-a (Chla) (3.63 mg/L), and lipid production (0.28 g/L) were all the highest comparing with other groups. In contrast, the protein production (0.37 g/L) was the least. The nature of the regulatory mechanisms inthe metabolic pathways of these biochemical compositions was revealed by proteomic results, and there were 62 different expression proteins (DEPs) taken part in fatty acid and lipid biosynthesis metabolism (FA), amino acid biosynthesis metabolism (AA), photosynthesis (PHO), carbon fixation in photosynthetic organisms (CFP), and central carbon metabolism (CCM).

Operation performance of an A/O process combined sewage sludge treatment and phosphorus recovery using human urine.

A novel sewage sludge treatment process is developed in which sludge anaerobically phosphorus (P) released with the temperature control/ultrasonic treatment and recovery with human urine are incorporated to a conventional anaerobic/aerobic (A/O) process. The results showed that temperature affected the anaerobic P release and the maximum orthophosphate (PO4 3-P) release rate was 21.68 mg PO4 3-P/(g MLVSS.h) at 20 °C. The optimal specific energy of ultrasonic treatment was 15,000 kJ/kg TS, at which the solubilization degree of soluble chemical oxygen demand (SCOD) was 37.93%, which verified that the anaerobic sludge flocs were broken and the organic matter was obviously released. Human urine and P-rich sludge stream could be verified as a feasible way of P recovery in the form of struvite. The output of P in the combined A/O treatment process consisted of three pathways (i.e., effluent wastewater, sewage sludge, and P recovery). The influent P could be recovered by 22.84% and about 1.48 g/d potential struvite could be recovered from the anaerobic sludge flow using 0.27 L/d-human urine. The mass balances of COD and nitrogen (N) indicated that the combined A/O process also improved the organic mineralization and the removal of N.

Enhancement of Lipid Production of Chlorella Pyrenoidosa Cultivated in Municipal Wastewater by Magnetic Treatment.

Despite the significant breakthroughs in research on microalgae as a feedstock for biodiesel, its production cost is still much higher than that of fossil diesel. One possible solution to overcome this problem is to optimize algal growth and lipid production in wastewater. The present study examines the feasibility of using magnetic treatment for enhancement of algal lipid production and wastewater treatment in outdoor-cultivated Chlorella pyrenoidosa. Results confirmed that magnetic treatment significantly enhances biomass and lipid productivity of C. pyrenoidosa by 12 and 10 %, respectively. Application of magnetic field in a semi-continuous culture resulted in highly treated wastewater with total nitrogen maintained under 15 mg L-1, ammonia nitrogen below 5 mg L-1, total phosphorus less than 0.5 mg L-1, and CODCr less than 50 mg L-1. In addition, magnetic treatment resulted in a decrease of wastewater turbidity, an increase of bacterial numbers, and an increase of active oxygen in wastewater which might be attributed to the enhancement of growth and lipid production of C. pyrenoidosa.

[Process fundamentals and field demonstration of wheat straw enhanced salt leaching of petroleum contaminated farmland].

A new remediation method for petroleum-salt contaminated soil was proposed, in which wheat straw was applied to enhance salt leaching and meanwhile block salt upmovement along the soil capillary. It was shown that the existence of petroleum increased the surface hydrophobicity of soil and thus hindered the leaching process once the oil content was above 1.5% (mass fraction). The application of 5% (mass fraction) wheat straw into the soil increased the efficiency of salt leaching from 3% to 25%. The effectiveness of wheat straw layer in inhibiting the salt upmovement along the soil capillary was also proven. Field test of this method was carried out in an area of 6400 m2, in which wheat straw layer of 5 cm was distributed in the depth of 25 cm. After 50 days, 80% of the testing area showed a normal soil electronic conductivity (soil EC <5 mS x cm(-1)) in contrast to 17% before leaching process. The concentrations of Na+ and Cl- were decreased from 1642.5 mg x kg(-1) and 1 301.2 mg x kg(-1) to 499.3 mg x kg(-1) and 433.8 mg x kg(-1), respectively. The remediated land upon the implementation of wheat straw gave a 72% of the regular wheat production obtained from the normal farmland, while the control land without wheat straw gave 12%. These results demonstrated the effectiveness and the high potential of using wheat straw for the salt leaching in remediation of petroleum-salt contaminated soil.

[Process fundamentals and field demonstration of wheat straw enhanced biodegradation of petroleum].

A new bioaugmentation method utilizing wheat straw to enhance salt leaching and the subsequent petroleum biodegradation by consortia of bacteria and fungi was proposed. The present study aimed at the effects of wheat straw on the growth and the degradation behavior of E. cloacae and Cun. echinulata, the two species of the consortia. In the laboratory experiments, it was shown that the addition of 5% (mass fraction) straw led to an increase of biomass by 25- and 3-fold to the bacteria and fungi, respectively. The biodegradation ratio of total petroleum hydrocarbon (TPH) was elevated from 29.2% to 48.0% after 468 h treatment. The biodegradation ratio of alkane and aromatic hydrocarbons in petroleum were increased from 31.5% and 39.1%, to 55.7% and 55.9%, respectively. The field demonstration was carried in an area of 6400 m2, in which the bacteria and fungi were inoculated after salt leaching in the presence of wheat straw. The addition of wheat straw in the contaminated soil led to an increase by 158- and 9-fold to the bacteria and fungi, as compared to their counterpart in the controlland without wheat straw, at 25 days after the inoculation. The content of TPH was down to below 0.3% while the maximum biodegradation ratio of TPH reached 75% after 45 days treatment. These results demonstrated the effectiveness and high potential of the wheat straw enhanced bioaugmentation of petroleum-salt contaminated soil.

Enhanced bioaugmentation of petroleum- and salt-contaminated soil using wheat straw.

A new bioaugmentation method for petroleum- and salt-contaminated soil was presented, in which wheat straw was used to enhance salt leaching and subsequent petroleum degradation by a bacteria-fungi consortium of Enterobacter cloacae and Cunninghamella echinulata. The effectiveness of a coarse wheat straw layer in inhibiting capillary-induced upward salt movement and in enhancing growth of E. cloacae and C. echinulata was shown in the laboratory and a 7000-m(2) field study in Henan Province, China. In the field study, the Na(+) concentration in remediated soil at 1-25 cm depth decreased from 1597 ± 394 to 543 ± 217 mg kg(-1), while Cl(-) decreased from 1520 ± 922 to 421 ± 253 mg kg(-1). The wheat straw increased bacterial biomass by 170-fold and fungi 11-fold compared to control soil without wheat straw. The concentration of total petroleum hydrocarbons decreased from 6320 ± 1180 to 2260 ± 420 mg kg(-1) after 45 d of treatment. Wheat was cultivated on remediated soil and grain yield reached 72% of that obtained in normal farmland adjacent to the study site. The results demonstrated the effectiveness of wheat straw in enhancing bioaugmentation of the petroleum- and salt-contaminated soil and indicated a high application potential.

[Field scale demonstration of fungi-bacteria augmented remediation of petroleum-contaminated soil].

Pilot demonstration of the fungal-bacterial augmented in situ remediation of petroleum contaminated soil was carried out in Zhongyuan Oilfield, Henan, using artificially prepared soil, newly and aged contaminated soil as sample, respectively. For the first run of the experiment started from Nov. 5, 2004 and lasted for 122 days, the removal of contaminate was 61.0%, 48.3% and 38.3% for diesel, lube and crude oil, respectively. For the second run started from May 18, 2005 and lasted for 161 days, the removal of TPH was 75% for the artificially contaminated soil sample while 46.0% and 56.6% for the fresh and aged contaminated soil. The removal of high concentration salt was involved in the remediation of the freshly and aged contaminated soil. The changes of the petroleum composition was monitored during the remediation process, which confirmed the effective degradation of alkanes, aromatic hydrocarbons and non-hydrocarbon compounds by the fungi-bacteria consortia, as compared to that obtained without the inoculation of the consortia. To further demonstrate the remediation, wheat was planted in above reclaimed soil. While wheat production in the reclaimed artificially contaminated soil yielded nearly as much as that obtained in the normal farmland, the output of wheat in the reclaimed refresh and aged contaminated soil was 57.2% and 70.3% of the averaged output of the normal farmland. The above results further confirmed the workability of fungal-bacterial augmented in situ remediation of petroleum contaminated soil and its application potential as well.

[Non-filamentous sludge bulking caused by low concentration of dissolved oxygen and phosphorus deficiency and its control].

Non-filamentous sludge bulking occurred during sludge acclimation in lab-scale bio-reactors and the characteristics, properties and degrading pollutants capability of non-filamentous sludge were analyzed. Both low DO concentration (0 - 0.7 mg/L) and low ratio of P/BOD5 (0.78/100) resulted in excessive proliferation of viscous zoogloea and sludge bulking. SVI was directly proportional to extracellular polysaccharides and was inversely proportional to hydrophobicity of sludge. The sludge bulking could be effectively controlled by increasing DO concentration and P/BOD5 ratio. Besides, adding some porous padding into viscous bulking sludge was a useful method which might avoid the deterioration of sludge settlement and maintain good performance in the system. The viscous bulking sludge could not be controlled by addition of NaC1O.

[Performance of treating wastewater and anti-shockloading in oxic-settling-anaerobic (OSA) process for minimization of excess sludge].

Efficiency of pollution degradation, performance of activated sludge, effect of temperature fluctuation and recalcitrant organic compounds on system stability were investigated in OSA process for minimization of excess sludge. CAS process and OSA process were run with synthetic wastewater for 240 d. The results indicate that the OSA process excels the CAS process as a whole. COD removal efficiency in OSA process was slightly more than that in CAS. Removal efficiency of nitrogen and phosphorus could be enhanced to 42.58% and 53.84% respectively. Biological phosphorus accumulation in aerobic sludge from OSA and CAS were 2.69 g and 1.11 g per 100 g dry sludge, which further approved biological phosphorus removal in OSA process. Because of alternative aerobic and anaerobic environment in OSA process, sludge settleability and activity are improved. SVI in OSA process was 97 averagely. SOUR and dehydrogenase activity of sludge in OSA were higher appreciably than those in CAS. Protein concentration was higher above 1.69 mg x g(-1) and polysaccharide concentration was lower 6.7 mg x g(-1) in OSA sludge than those in CAS, which confirms the effect of anaerobic tank on sludge performance and microorganism diversity. Lower polysaccharide concentration in OSA sludge improves the settleability. Contrasting to CAS process, OSA process is more sensitive to impact of p-nitrophenol(PNP) and more inactive to temperature fluctuation. Temperature fluctuation led to an increase of the concentration of COD, NH4(+) -N, SS in effluent while sludge production Y(MLSS/COD) was reduced to 0.403 mg x mg(-1) and 0.227 mg x mg(-1) in CAS and OSA. When concentration of PNP was increased abruptly to 10 mg x L(-1), biological nutrient removal was ceased in OSA process. Once OSA system is impacted, it is difficult to restore.