Application of Rice-Straw Biochar and Microorganisms in Nonylphenol Remediation: Adsorption-Biodegradation Coupling Relationship and Mechanism

Abstract

Biochar adsorption presents a potential remediation method for the control of hydrophobic organic compounds (HOCs) pollution in the environment. It has been found that HOCs bound on biochar become less bioavailable, so speculations have been proposed that HOCs will persist for longer half-life periods in biochar-amended soil/sediment. To investigate how biochar application affects coupled adsorption-biodegradation, nonylphenol was selected as the target contaminant, and biochar derived from rice straw was applied as the adsorbent. The results showed that there was an optimal dosage of biochar in the presence of both adsorption and biodegradation for a given nonylphenol concentration, thus allowing the transformation of nonylphenol to be optimized. Approximately 47.6% of the nonylphenol was biodegraded in two days when 0.005 g biochar was added to 50 mg/L of nonylphenol, which was 125% higher than the relative quantity biodegraded without biochar, though the resistant desorption component of nonylphenol reached 87.1%. All adsorptive forms of nonylphenol (f rap, f slow, f r) decreased gradually during the biodegradation experiment, and the resistant desorption fraction of nonylphenol (f r) on biochar could also be biodegraded. It was concluded that an appropriate amount of biochar could stimulate biodegradation, not only illustrating that the dosage of biochar had an enormous influence on the half-life periods of HOCs but also alleviating concerns that enhanced HOCs binding by biochar may cause secondary pollution in biochar-modified environment.

Enhancement of As(v) adsorption from aqueous solution by a magnetic chitosan/biochar composite

“…17 Compared with conventional carbonaceous materials such as commercial activated carbon, the primary advantages of biochar are its low cost and a wealth of sources of biomass. 18,19 However, pristine biochar prepared from biomass feedstock without any treatment have relatively low heavy metal sorption capacity, and their sorption for aqueous As, which is in anionic forms of either arsenate (As(V)) or arsenite (As(III)), is relatively low due to most of biochar are predominantly net negatively charged on the surface. 20 Several methods have thus been developed to modify biochar to enhance its sorption for As.…”

Effect of rice-straw biochar on selective biodegradation of nonylphenols in isomer specificity

“…In this study, the degradation of the NP isomers was affected by two factors: (1) the bioavailability of NP isomers, which was evidently restricted due to the strong adsorptive properties of the biochar, and (2) microorganisms, which could be adsorbed by or attached to biochar, form biofilms, and thereby readily promote microorganism growth (Yang and Sheng 2003a, b). The forming of biofilms with the attached abundant microorganisms could be an important mechanism in overcoming the limitations of mass transfer, shortening diffusion distance, and enhancing biodegradation as shown in previous studies (Lou et al 2015;Mercier et al 2014). It should be noted that biochar acted in a leading role by inhibiting or promoting the biodegradation of the NP isomers in separate degradation periods; the degradations required certain durations to enable microorganism growth.…”

“…A tNP-degrading bacterial strain was isolated from a mixed inoculum from sediments with NP as the sole C source from the Qiantang River in Hangzhou, China, based on previous work (Lou et al 2015). The cell morphology, physiological characteristics, and 16S rRNA genes of the strain were characterized by the Institute of Microbiology, Chinese Academy of Sciences.…”

“…The adsorption capacity of biochar for NP has been reported to reach up to 3.3 ± 0.3 × 10 4 mg/kg, suggesting that biochar could be used for immobilizing NP at contaminated sites (Lou et al 2014). Furthermore, the application of appropriate levels of biochar could enhance NP biodegradation rates and achieve effective coupled sorption-biodegradation remediation (Lou et al 2015). However, NP is not a single compound but a complex mixture of more than 100 NP isomers (Eganhouse et al 2009).…”

Bioflocculant BF-R1 production by Bacillus sp. R1 using wheat bran hydrolysate and its application in wastewater treatment

“…Granular activated carbon addition into the batchmode anaerobic sludge digestion reactor could significantly accelerate substrate consumption and methane production (Yang et al, 2017). Biochar derived from rice straw can be applied to adsorb the endocrine disrupter nonylphenol (NP), and thus accelerating its biodegradation (Lou et al, 2015). However, granular carbon particles, particularly ultrafine particles (< 5 µ in diameter), create problems during screening and tend to float in water (Vijayalakshmi and Raichur, 2003).…”