Groundwater antibiotics and microplastics in a drinking-water source area, northern China: Occurrence, spatial distribution, risk assessment, and correlation.

In recent years, antibiotics and microplastics have both received increasing attention. However, the contamination and correlation between the two pollutants in the groundwater of drinking-water source areas has not yet been considered. In this study, eight antibiotics were detected in 81 groundwater samples from a drinking-water source area. These were trimethoprim (TMP), sulfadimidine (SDD), sulfadiazine (SDZ), sulfamethoxazole (SMX), sulfachloropyridazine (SCP), norfloxacin (NOR), ciprofloxacin (CIP) and enrofloxacin (ENRO). Detection rates ranged from 1.23% to 95.06% and the maximum concentration ranged from 0.44 ng/L to 45.40 ng/L. Antibiotics in the groundwater pose no threat to human health, while only ENRO, CIP, NOR, SMX, and SDZ posed medium to low risks to the aquatic ecosystem. In contrast, the detection rate of microplastics was 100% with abundance values ranging from 4 n/L to 72 n/L, with an average of 29 n/L. Microplastic polymers were identified as polyamide, polyethylene, polypropylene, polyvinyl chloride and polystyrene. These also occurred in surface water but the particle sizes in groundwater were lower than those in the surface water. Through correlation analysis, it was found that NOR, ENRO and total antibiotic concentrations were significantly correlated with microplastic abundances. This study revealed the contamination and potential risks of antibiotics and microplastics in the groundwater of a drinking-water source area and found a correlation between them, indicating that risk management of antibiotics and microplastics in groundwater should be highly concerned.

A newly-constructed bifunctional bacterial consortium for removing butyl xanthate and cadmium simultaneously from mineral processing wastewater: Experimental evaluation, degradation and biomineralization.

Due to the technological limitations associated with beneficiation technology, large amounts of flotation reagents and heavy metals remain in mineral processing wastewater. Unfortunately, however, no treatment methods are available to mitigate the resulting pollution by them. In this study, a bacterial consortium SDMC (simultaneously degrade butyl xanthate and biomineralize cadmium) was constructed in an effort to simultaneously degrade butyl xanthate (BX) and biomineralize cadmium (Cd) by screening and domesticating two different bacterial species including Hypomicrobium and Sporosarcina. SDMC is efficient in removing the combined pollution due to BX and Cd with a 100% degradation rate for BX and 99% biomineralization rate for Cd within 4 h. Besides, SDMC can tolerate high concentrations of Fe(III) (0-40 mg/L). It has an excellent ability to utilize Fe(III) for enhanced removal of the combined pollutants. SDMC can effectively remove pollutants with a pH range of 6-9. Further, we discussed pathways for potential degradation and biomineralization: Cd(BX)2-Cd2+, BX-; BX--CS2, butyl perxanthate (BPX); Cd2+-(Ca0.67,Cd0.33)CO3. The removal of the combined pollutants primarily entails decomposition, degradation, and biomineralization, C-O bond cleavage, and microbially induced carbonate precipitation (MICP). SDMC is a simple, efficient, and eco-friendly bifunctional bacterial consortium for effective treatment of BX-Cd combined pollution in mineral processing wastewater.