This paper explored the possibility of heterotrophic denitrification driven by composite solid carbon sources in low carbon/nitrogen ratio marine recirculating aquaculture wastewater. In this study, two agricultural wastes, reed straw (RS), corn cob (CC) and two artificial polymers, polycaprolactone (PCL), poly3-hydroxybutyrate-hydroxypropionate (PHBV) were mixed in a 1:1 ratio to compare the carbon release characteristics of the four composite carbon sources (RS+PCL, RS+PHBV, CC+PCL, and CC+PHBV) and their effects on improving the mariculture wastewater for denitrification. Dissolved organic carbon (DOC) after carbon source release (4.96-1.07 mg/g), total organic carbon/chemical oxygen demand (1.9-0.79) and short-chain fatty acids (SCFAs) (4.23-0.21 mg/g) showed that all the four composite solid carbon sources had excellent organic carbon release ability, and the CC+PCL group had the highest release of DOC and SCFAs. Energy-dispersive X-ray spectroscopy, scanning electron microscopy, and Fourier-transform infrared spectroscopy were used to observe the changes in the surface characteristics of the composite carbon source before and after application. And results showed that the stable internal structure enabled CC+PCL group to have continuous carbon release performance and achieved the maximum denitrification efficiency (93.32 %). The NRE results were supported by the abundance of the Proteobacteria microbial community at the phylum level and Marinobacter at the genus level. Quantitative real-time PCR (q-PCR) indicated CC-containing composite carbon source groups have good nitrate reduction ability, while PCL-containing composite carbon source groups have better nitrite reduction level. In conclusion, the carbon source for agricultural wastes and artificial polymers can be used as an economic and effective solid carbon source for denitrification and treatment of marine recirculating aquaculture wastewater.
Indirect photodegradation is one of the primary approaches for the removal of pharmaceutical contaminants from water. This degradation process is dominated by chromophoric dissolved organic matter (CDOM). After illumination, CDOM produces many reactive intermediates, which can react with drug pollutants to achieve indirect photodegradation. In this article, we focused on four different sources of CDOM and factors affecting indirect sulfamethoxazole (SMZ) photolysis. The results show that the indirect photodegradation effect of SMZ is significantly influenced by CDOM. This indirect photodegradation has a dual nature. It promotes the indirect photodegradation of SMZ through the formation of various reactive intermediates and at the same time inhibits the photodegradation of SMZ through light shielding and masking of reactive intermediates. The indirect photodegradation of SMZ is mainly controlled by active intermediates such as 3CDOM*, HO·, and 1O2 produced by CDOM; 3CDOM* is the main participant in indirect photodegradation of SMZ. In addition, the pH, salinity, and nitrate ions have a significant effect on the indirect photodegradation of SMZ, while bicarbonate ions have no significant effect on the indirect photodegradation of SMZ.
This paper analyzes the problems of the synchronous PPP in realizing the router based on embedded Linux,and designs some schemes. Compared with one another,the paper confirms one scheme and realizes it. Through the expremental results, this scheme can implement PAP and CHAP authentication. It can consult NCP successfully also. The velocity of the synchronous serial interface can come to 2Mbps.
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