Removal of humic acid from composted hog waste by the white-rot fungus, Phanerochaete chrysosporium

Advances in Circular Bioeconomy Technologies: From Agricultural Wastewater to Value-Added Resources

This review systematically outlines the recent advances in the application of circular bioeconomy technologies for converting agricultural wastewater to value-added resources. The properties and applications of the value-added products from agricultural wastewater are first summarized. Various types of agricultural wastewater, such as piggery wastewater and digestate from anaerobic digestion, are focused on. Next, different types of circular technologies for recovery of humic substances (e.g., humin, humic acids and fulvic acids) and nutrients (e.g., nitrogen and phosphorus) from agricultural wastewater are reviewed and discussed. Advanced technologies, such as chemical precipitation, membrane separation and electrokinetic separation, are evaluated. The environmental benefits of the circular technologies compared to conventional wastewater treatment processes are also addressed. Lastly, the perspectives and prospects of the circular technologies for agricultural wastewater are provided.

Effect of lignocellulosic enzymes on the treatment of mature landfill leachate

The inherent necessity to remediate refractory contaminants from the toxic problematic wastewater like mature landfill leachate (MLL) has become a global challenge. This study investigated the effect of a potentially sustainable technological approach, i.e. lignocellulosic enzymatic activities (lignin-peroxidase, manganese-peroxidase and laccase), produced from six selected fungi on the removal efficiency of chemical oxygen demand (COD) and soluble COD (sCOD) from the MLL. The COD/sCOD removal percentage was significantly increased with higher enzymatic activities. Tyromyces chioneus was revealed to be the first ever fungi that produced significant amount of all three enzymes. Penicillium sp. and Tyromyces chioneus were the most effective strains, which removed 66% and 59% of COD, and 64% and 57% of sCOD, respectively. The maximum lignin-peroxidase, manganese-peroxidase and laccase enzymatic activities were 19.3 and 26.9 U/L by Tyromyces chioneus, and 249.8 U/L by Penicillium sp, respectively. It was concluded that lignocellulosic biomass could be a sustainable and advanced biological treatment option to remove refractory components from MLL.

Fungal pretreatment of raw digested piggery wastewater enhancing the survival of algae as biofuel feedstock

BACKGROUND

Understanding about the impact of white rot fungi on indigenous bacterial communities, NH₄⁺ and turbidity in digested piggery wastewater, will allow the optimization of wastewater treatment methods and its use as a feasible medium for algal growth. Here, the white rot fungi were inoculated into undiluted and unsterilized digested piggery wastewater under different temperatures and pH regimes in order to lower the pretreatment cost. Diversity and abundance of the bacterial communities in the pretreated wastewater were assessed by PCR-denaturing gradient gel electrophoresis coupled with 16S rDNA sequencing.

RESULTS

The research showed a significant reduction on the microbial diversity with the presence of white rot fungi which occur at pH 6. The distribution and presence of bacteria taxa were strongly correlated with NH₄⁺ concentration, pH, and the presence of white rot fungi. Variance partition analysis also showed that the effect on the chlorophyll content of algae in fungi-filtered wastewater was as the following hierarchy: bacterial diversity > NH₄⁺ > turbidity. Therefore, the algae in treated wastewater with less abundance of bacteria proliferated more successfully, indicating that bacterial community not only played an important role in algal growth but also imposed a strong top-down control on the algal population. The algae grown in wastewater treated with fungi reached the highest specific growth rate (0.033 day^-1), whereas the controls displayed the negative specific growth rate. The fatty acid composition varied markedly in C16:0 and C18:0 between these treatments, with a higher content of C16:0.

CONCLUSIONS

This study firstly showed that Chlorella can grow as cost-effective biofuel feedstocks in undiluted and unsterilized digested wastewater with high ammonium concentration and dark brown color because the bacterial abundance of digested piggery wastewater could be reduced greatly by the white rot fungi.