The development and optimisation of a lab-scale process for biological treatment of lignin-rich wastewater using biofilms formed by Nuerospora Discreta

Lignin is a complex biopolymer found in lignocellulosic materials used as raw material in pulp and paper making. Lignin is processed as a by-product of low value and is discarded in the wastewater. This wastewater is highly polluting due to dissolved lignin degradation products, which give it an intense colour and high chemical oxygen demand (COD), causing harm to aquatic life, plants, and animals. Removal or degradation of lignin has been shown to improve water quality in industrial wastewater, however, the complex structure of lignin makes it difficult to be degraded. Advancements in wastewater treatment methods, such as the conventional physiochemical and thermochemical methods employed, have a detrimental impact on the environment due to the production of hazardous by-products and high energy requirements. Biological treatment of lignin using fungi has the potential to overcome many of these roadblocks and lead to a successful process. This thesis aims to develop a single-step biological process for treating wastewater from the kraft process used in paper-making. Neurospora discreta, an ascomycete fungus, has been reported to degrade lignin effectively in lignocellulosic biomass, as it possesses the ligninolytic enzymatic machinery required for lignin degradation. It also has a unique ability to form robust biofilms at the air and liquid interface. In this research, N. discreta was evaluated for its ability to treat lignin-rich wastewater for the first time. The process optimisation was initially developed on synthetic wastewater using alkali lignin, followed by studies using wastewater provided by a pulp and paper-producing company. Firstly, the Taguchi statistical design of experiments, was used to identify the critical process levers for enhancing lignin degradation. Secondly, the addition of naturally formed lignin degradation intermediates in the fungal-treated wastewater spent media was evaluated as a strategy to increase lignin and COD removal. Finally, the biofilms were tested in a continuous repeated batch process, where actively metabolising mature biofilms were transferred to fresh wastewater in repeated cycles. The process was then scaled-up eightfold to tray reactors. This research has developed a fungal biofilm-based sustainable, eco-friendly and scalable alternative for lignin and COD removal in industrial wastewater. The fungal biofilm treatment proved to be efficient in removing 67.8% of standard kraft lignin in synthetic wastewater. The process efficiencies, while treating real wastewater from pulp and paper mill, were improved significantly by using lignin degradation intermediates as additives. The lignin and COD removal efficiencies of 70% were noted in cultures fed with lignin degradation intermediates compared to 57% and 50% respectively, in unfed culture. Enzyme activity for polyphenol oxidase (PPO), versatile peroxidase (VPO) and laccase were also seen where VPO was reported for the first time in a Neurospora species. The repeated-batch treatment process was evaluated and resulted in an efficient scalable process

Generalized Parton Distributions from Hadronic Observables

We propose a physically motivated parametrization for the unpolarized generalized parton distributions, H and E, valid at both zero and non-zero values of the skewness variable, \zeta. At \zeta=0, H and E are determined using constraints from simultaneous fits of experimental data on both the nucleon elastic form factors and the deep inelastic structure functions. Lattice calculations of the higher moments constrain the parametrization at \zeta > 0. Our method provides a step towards a model independent extraction of generalized distributions from the data that is alternative to the mathematical ansatz of double distributions.Comment: 4 pages, 2 figures, to appear in the proceedings of DIS 200

The length of time's arrow

An unresolved problem in physics is how the thermodynamic arrow of time arises from an underlying time reversible dynamics. We contribute to this issue by developing a measure of time-symmetry breaking, and by using the work fluctuation relations, we determine the time asymmetry of recent single molecule RNA unfolding experiments. We define time asymmetry as the Jensen-Shannon divergence between trajectory probability distributions of an experiment and its time-reversed conjugate. Among other interesting properties, the length of time's arrow bounds the average dissipation and determines the difficulty of accurately estimating free energy differences in nonequilibrium experiments

Biofilm-based simultaneous nitrification, denitrification, and phosphorous uptake in wastewater by Neurospora discreta

Biological removal of nitrogen and phosphorous from wastewater conventionally involves multiple processing steps to satisfy the differing oxygen requirements of the microbial species involved. In this work, simultaneous nitrification, denitrification, and phosphorous removal from synthetic wastewater were achieved by the fungus Neurospora discreta in a single-step, biofilm-based, aerobic process. The concentrations of carbon, nitrogen, and phosphorous in the synthetic wastewater were systematically varied to investigate their effects on nutrient removal rates and biofilm properties. Biofilm growth was significantly (p < 0.05) affected by carbon and nitrogen, but not by phosphorous concentration. Scanning electron microscopy revealed the effects of nutrients on biofilm microstructure, which in turn correlated with nutrient removal efficiencies. The carbohydrate and protein content in the biofilm matrix decreased with increasing carbon and nitrogen concentrations but increased with increasing phosphorous concentration in the wastewater. High removal efficiencies of carbon (96%), ammonium (86%), nitrate (100%), and phosphorus (82%) were achieved under varying nutrient conditions. Interestingly, decreasing the phosphorus concentration increased the nitrification and denitrification rates, and decreasing the nitrogen concentration increased the phosphorus removal rates significantly (p < 0.05). Correlations between biofilm properties and nutrient removal rates were also evaluated in this study

Isoform-specific 3\u27-untranslated sequences sort alpha-cardiac and beta-cytoplasmic actin messenger RNAs to different cytoplasmic compartments

We demonstrate that in differentiating myoblasts, the mRNAs encoding two actin isoforms, beta-cytoplasmic, and alpha-cardiac, can occupy different cytoplasmic compartments within the same cytoplasm. beta-actin mRNA is localized to the leading lamellae and alpha-actin mRNA is associated with a perinuclear compartment. This was revealed by co-hybridizing, in situ, fluorochrome-conjugated oligonucleotide probes specific for each isoform. To address the mechanism of isoform-specific mRNA localization, molecular chimeras were constructed by insertion of actin sequences between the Lac Z coding region and SV-40 3\u27UTR in a reporter plasmid. These constructs were transiently expressed in a mixed culture of embryonic fibroblasts, myoblasts and myotubes, beta-galactosidase activity within transfectants was revealed by a brief incubation with its substrate (X-gal). Since the blue-insoluble reaction product co-localized with the specific mRNAs expressed from each construct, it was used as a bioassay for mRNA localization. Transfectants were scored as either perinuclear, peripheral or nonlocalized with respect to the distribution of the blue product. The percentage of transfectants within those categories was quantitated as a function of the various constructs. This analysis revealed that for each actin mRNA its 3\u27UTR is necessary and sufficient to direct reporter transcripts to its appropriate compartment; beta-actin peripheral and alpha-actin perinuclear. In contrast, sequences from the 5\u27UTR through the coding region of either actin gene did not localize the blue product. Therefore, 3\u27UTR sequences play a key role in modulating the distribution of actin mRNAs in muscle cells. We propose that the mechanism of mRNA localization facilitates actin isoform sorting in the cytoplasm