Industrial wastewaters and dewatered sludge: rich nutrient source for production and formulation of biocontrol agent, Trichoderma viride

Mitigating nitrous oxide emissions from tea field soil using bioaugmentation with a Trichoderma viride biofertilizer

Land-use conversion from woodlands to tea fields in subtropical areas of central China leads to increased nitrous oxide (N₂O) emissions, partly due to increased nitrogen fertilizer use. A field investigation of N₂O using a static closed chamber-gas chromatography revealed that the average N₂O fluxes in tea fields with 225 kg N ha⁻¹ yr⁻¹ fertilizer application were 9.4 ± 6.2 times higher than those of woodlands. Accordingly, it is urgent to develop practices for mitigating N₂O emissions from tea fields. By liquid-state fermentation of sweet potato starch wastewater and solid-state fermentation of paddy straw with application of Trichoderma viride, we provided the tea plantation with biofertilizer containing 2.4 t C ha⁻¹ and 58.7 kg N ha⁻¹. Compared to use of synthetic N fertilizer, use of biofertilizer at 225 kg N ha⁻¹ yr⁻¹ significantly reduced N₂O emissions by 33.3%–71.8% and increased the tea yield by 16.2%–62.2%. Therefore, the process of bioconversion/bioaugmentation tested in this study was found to be a cost-effective and feasible approach to reducing N₂O emissions and can be considered the best management practice for tea fields.

Potential use of filamentous fungi for wastewater sludge treatment

Specific filamentous fungi (FF) have been recognized for sludge treatment and possibly these strains can be utilized for simultaneous bioflocculation, solids and pathogens reduction and, removal and degradation of toxic compounds. Based on current research work and findings, this review provides the state-of-art knowledge on the role of FF (or moulds) in sludge treatment. The proposed theories are presented, critically analyzed and future scope for specific research on utilization of FF for treatment of sludge is recommended.

Physico-chemical pre-treatment and biotransformation of wastewater and wastewater sludge--fate of bisphenol A

Bisphenol A (BPA), an endocrine disrupting compound largely used in plastic and paper industry, ends up in aquatic systems via wastewater treatment plants (WWTPs) among other sources. The identification and quantification of BPA in wastewater (WW) and wastewater sludge (WWS) is of major interest to assess the endocrine activity of treated effluent discharged into the environment. Many treatment technologies, including various pre-treatment methods, such as hydrolysis, Fenton oxidation, peroxidation, ultrasonication and ozonation have been developed in order to degrade BPA in WW and WWS and for the production of WWS based value-added products (VAPs). WWS based VAPs, such as biopesticides, bioherbicides, biofertilizers, bioplastics and enzymes are low cost biological alternatives that can compete with chemicals or other cost intensive biological products in the current markets. However, this field application is disputable due to the presence of these organic compounds which has been discussed with a perspective of simultaneous degradation. The pre-treatment produces an impact on rheology as well as value-addition which has been reviewed in this paper. Various analytical techniques available for the detection of BPA in WW and WWS are also discussed. Presence of heavy metals and possible thermodynamical behavior of the compound in WW and WWS can have major impact on BPA removal, which is also included in the review.

Pre-treatment and bioconversion of wastewater sludge to value-added products--fate of endocrine disrupting compounds

Development of processes for the production of value added products (VAPs), such as biopesticides, microbial inoculants or industrial enzymes through biotransformation of raw or pre-treated wastewater sludge (WWS) has undergone a substantial progress over the last decade. WWS based VAPs are low cost biological alternatives that can compete with chemicals or other cost intensive biological products in the current markets. However, when WWS is used as a raw material for VAPs production, questions still remains on the persistence of organic pollutants within the biotransformed WWS, especially, endocrine disrupting compounds (EDCs) and the production of their toxic intermediates. WWS pre-treatment prior to biotransformation as well as the microbial strains used for biotransformation can possibly remove these organic pollutants. The literature findings concerning the impact of WWS pre-treatment and value added products on EDCs removal are reviewed in this paper. The microbial potential to degrade or detoxify EDCs and toxic intermediates concomitant with value-addition is also discussed. The concept of obtaining EDCs free-WWS based VAPs and simultaneously achieving the objective of pollution control is presented.