Mixed sulfur-iron particles packed reactor for simultaneous advanced removal of nitrogen and phosphorus from secondary effluent.

A mixed sulfur-iron particles packed reactor (SFe reactor) was developed to simultaneously remove total nitrogen (TN) and total phosphorus (TP) of the secondary effluent from municipal wastewater treatment plants. Low effluent TN (<1.5 mg/L) and TP (<0.3 mg/L) concentrations were simultaneously obtained, and high TN removal rate [1.03 g N/(L·d)] and TP removal rate [0.29 g P/(L·d)] were achieved at the hydraulic retention time (HRT) of 0.13 h. Kinetic models describing denitrification were experimentally obtained, which predicted a higher denitrification rate [1.98 g N/(L·d)] of SFe reactor than that [1.58 g N/(L·d)] of sulfur alone packed reactor due to the mutual enhancement between sulfur-based autotrophic denitrification and iron-based chemical denitrification. A high TP removal obtained in SFe reactor was attributed to chemical precipitation of iron particles. Microbial community analysis based on 16S rRNA revealed that autotrophic denitrifying bacteria Thiobacillus and Sulfuricella were the dominant genus, indicating that autotrophic denitrification played important role in nitrate removal. These results indicate that sulfur and iron particles can be packed together in a single reactor to effectively remove nitrate and phosphorus.

[Research on sorption and transport characteristics of ligninolytic enzymes in different compost substances].

To understand the characteristics of ligninolytic enzymes sorption and transport in different compost substances, ligninolytic enzymes adsorption on soil, vegetable leaf, rice straw and chaff was comparatively studied through batch jar tests and relevant kinetics and isotherm equilibrium were discussed as well as a column experiment was performed to study the process of transport. The results showed that the sorption efficiency was depended on the sorts of substances. The adsorptive capacities of soil, vegetable leaf, rice straw and chaff to lignin peroxidase (LiP) were 1.22 U x g(-1), 1.27 U x g(-1), 1.13 U x g(-1), 1.22 U x g(-1) and to manganese peroxidase (MnP) were 5.09 U x g(-1), 4.88 U x g(-1), 4.43 U x g(-1), 3.95 U x g(-1), respectively. Comparing the kinetic models of LiP and MnP adsorption, the pseudo-second-order reaction model (R2 0.973-0.999 7) was the best of the models. Elovich equation was a bit better than pseudo-first-order kinetic which was the worst. The equilibrium data could be fitted well with Langmuir model while it could not satisfied with Freundlich model. The adsorptive saturation of soil, vegetable leaf, rice straw and chaff to LiP were 1.23 U x g(-1), 1.30 U x g(-1), 1.17 U x g(-1), 1.14 U x g(-1) and to MnP were 5.70 U x g(-1), 5.19 U x g(-1), 4.73 U x g(-1), 4.14 U x g(-1). LiP and MnP had good transport capability in straw and chaff to move to the deepest layer of 10 mL while remained in the superficial layers in soil and vegetable leaf.

Changes of microbial population structure related to lignin degradation during lignocellulosic waste composting.

Microbial populations and their relationship to bioconversion during lignocellulosic waste composting were studied by quinone profiling. Nine quinones were observed in the initial composting materials, and 15 quinones were found in compost after 50days of composting. The quinone species Q-9(H2), Q-10 and Q-10(H2) which are indicative of certain fungi appeared at the thermophilic stage but disappeared at the cooling stage. Q-10, indicative of certain fungi, and MK-7, characteristic of certain bacteria, were the predominant quinones during the thermophilic stage and were correlated with lignin degradation at the thermophilic stage. The highest lignin degradation ratio (26%) and good cellulose degradation were found at the cooling stage and were correlated with quinones Q-9, MK-7 and long-chain menaquinones attributed to mesophilic fungi, bacteria and actinomycetes, respectively. The present findings will improve the understandings of microbial dynamics and roles in composting, which could provide useful references for development of composting technology.

[Analysis of the effect of enzymes on microbial community metabolic profiles during composting using biolog method].

The effects of enzymes on organic material degradation and microbial communities metabolic profiles during composting process were studied using Biolog method, and together with cluster analysis and PCA. The results showed that, adding the enzyme solution in the composting could increase the degradation rate of organic material by 4.90%. The microbial community metabolic results of cluster analysis showed that when the enzyme solution was added into the compost, the carbon metabolic capability of intermediate metabolite was improved. The results of PCA indicated that when the enzyme solution was added, microbial communities enhanced the metabolic capability of miscellaneous, polymers, amino acids and amides carbon substrates, which results in the efficient degradation of organic substance. In addition, cluster analysis of each composting phase showed that the effects of the enzymes solution on microbial community metabolism were mainly observed on 6 d and 30 d, which promoted the composting process.

Degradation of lead-contaminated lignocellulosic waste by Phanerochaete chrysosporium and the reduction of lead toxicity.

Lead, as one of the most hazardous heavy metals to the environment interferes with lignocellulosic biomass bioconversion and carbon cycles in nature. The degradation of lead-polluted lignocellulosic waste and the restrain of lead hazards by solid-state fermentation with Phanerochaete chrysosporium were studied. Phanerochaete chrysosporium effectively degraded lignocellulose, formed humus and reduced active lead ions, even at the concentration of 400 mg/kg dry mass of lead. The highest lignocellulose degradation (56.8%) and organic matter loss (64.0%) were found at the concentration of 30 mg/kg of lead, and at low concentration of lead the capability of selective lignin biodegradation was enhanced. Microbial growth was delayed in polluted substrate at the initial stage of fermentation, and organic matter loss is correlated positively with microbial biomass after 12 day fermentation. It might be because Phanerochaete chrysosporium developed active defense mechanism to alleviate the lead toxicity. Scanning electron micrographs with energy spectra showed that lead was immobilized via two possible routes: adsorption and cation exchange on hypha, and the chelation by fungal metabolite. The present findings will improve the understandings about the degradation process and the lead immobilization pathway, which could be used as references for developing a fungi-based treatment technology for metal-contaminated lignocellulosic waste.