Occurrence, spatial distribution, and risk assessment of short- and medium-chain chlorinated paraffins in sediment from black-odorous rivers across China.

Chlorinated paraffins (CPs) were massively produced for varied industrial purposes, of which improper handling and consequent environmental release resulted in worldwide contamination. The present study investigated the occurrence and spatial distribution of short- and medium-chain chlorinated paraffins (SCCP/MCCPs) in 171 sediment samples from black-odorous urban rivers across China. Total SCCP and MCCP concentrations ranged from 8.3 to 9.4 × 104 (median: 1.1 × 103) ng/g dw, and from not-detected-value to 1.0 × 106 (median: 1.3 × 104) ng/g dw, respectively. No clear spatial distribution of SCCPs and MCCPs was observed since black-odorous urban rivers were polluted by point-sources of the SCCP/MCCPs. Significant positive correlations were identified between SCCP/MCCPs and total organic carbon, and between SCCP/MCCPs and other persistent organic matter, including polybrominated diethyl ethers, polychlorinated biphenyls, antibiotics, and plasticizers. The average ratios of MCCPs to SCCPs in most samples were divided into 11 and 16, implying the manufacturing and use of at least two types of CP technical mixtures in China. The composition of SCCP/MCCPs were similar to that in their commercial products. Ecological risk assessments by two approaches, including the Federal Environmental Quality Guidelines and Risk Quotient, both revealed that SCCP/MCCP in surface sediments confer an ecological risk. ENVIRONMENTAL IMPLICATION: SCCPs and MCCPs can be considered "hazardous materials" because of their massive production and their potential persistence, long-distance transfer, bioaccumulation potential, and toxicity. This research conducted a comprehensive study on SCCP/MCCP in black-odorous urban river sediments across China and revealed their environmental risk, which may improve understanding of SCCP/MCCP contamination characteristics.

Occurrence and distribution of antibiotics in sediments from black-odor ditches in urban areas from China.

Antibiotic levels in black-odor water could reflect the usage amount of antibiotics in population. On the other hand, these antibiotics are the source of antibiotics in the environmental water. Currently, researches on antibiotics in black-odor sediments are still lacking. In this study, 174 black and odor sediment samples from 74 cities in 28 provinces in China were collected for analysis. Among 44 targeted antibiotics, 13 antibiotics were detected in more than 30% of sediment samples. Fluoroquinolones and tetracyclines were the predominant antibiotics in these field samples, with average concentrations of up to 2074 and 1902 ng/g dry weight (dw), respectively, followed by macrolides (87.9 ng/g dw), lincosamides (8.06 ng/g dw) and sulfonamides (8.38 ng/g dw). High antibiotic contamination levels were almost always detected in black-odor sludges from economically less developed small cities; however, the difference in antibiotic concentrations between well-developed and small cities in China was not statistically significant. In addition, among the seven regions within China, no significant difference in concentrations was observed for the most antibiotics. Variances in antibiotic composition patterns in the 28 provinces of China may be due to differences in bacterial resistance, prescription habits, efficacy, and sediment carbon concentrations among various regions. There were significant positive correlations among some antibiotics in the same or different classes.

Degradation of triclosan by anodic oxidation/in-situ peroxone process: Kinetics, pathway and reaction mechanism.

Triclosan (TCS) is an emerging contaminant that threatens the environment and human health. This study was conducted to investigate TCS abatement by a novel electro-oxidation (EO) process, which used a Ti-based nickel and antimony doped tin oxide (NATO/Ti) anode and a carbon nanotubes (CNTs) doped carbon/PTFE (CNTs-C/PTFE) gas diffusion electrode (GDE) for oxygen reduction reaction (ORR). A comparative study was also performed for TCS degradation by using a traditional EO with a nickel foam cathode, termed as HER-EO. The optimal initial TCS concentration, current density and solution pH for TCS degradation during the ORR-EO and HER-EO were investigated. Results showed that ORR-EO removed more than 98% of TCS in 10-60 min under the concentration of 5-50 mg/L. The TCS degradation followed pseudo-first-order kinetics and its main intermediates were observed during the ORR-EO and HER-EO using liquid chromatography combined mass (LC-MS). The results of FED analysis and toxicity prediction by ECOSAR software showed that less intermediates accumulated during the ORR-EO and the residues were less harmful. The ORR-EO degradation mechanism for TCS was attacking on the ether bond and the benzene ring by •OH. This novel ORR-EO process exhibits a great merit in the field of emerging contaminants abatement.

[Filamentous overgrowth in aerobic granules].

Filamentous overgrowth has been observed after aerobic granulation in shaking sequencing batch reactors (SSBR). The factors affecting the filamentous overgrowth in aerobic granules and its possible control methods were investigated. It was found that both the influent and sludge inoculation largely influenced the filamentous overgrowth in aerobic granules. With the same activated sludge inoculation, the filamentous overgrowth in R3 treating fresh wastewater was much more severe than that in R1 treating saline wastewater. The filamentous overgrowth in R2 was the least among the three reactors, which was inoculated anaerobic granules and treated saline wastewater. When the filamentous overgrowth happened at the outer aerobic granules, Delta referring the degree of filamentous overgrowth achieved DeltaR1 = 1.4, DeltaR2 = 1.2 and DeltaR3 = 2.0, respectively. Filamentous identification showed that the filamentous microorganisms in R1 mainly composed of Eikelboom 0092 and Nocardia spp., Fungi spp. and Nocardia spp. in R2, S. natans and H. hydrossis in R3. The identified filamentous microorganisms likely occurred in conditions with long SRT, low dissolved oxygen and biodegradable substrates. However, due to the fact that filamentous overgrowth in aerobic granules initiated in the inner part of the granules and acted as frameworks with rod-shape or coccoid bacteria entrapping into in the granulation period, various strategies effectively in dealing with conventional bulking problems including shorting SRT, changing organic loading rate and enhancing aeration et al, could not effectively inhibit the filamentous growth in aerobic granules. The filamentous overgrowth was ultimately controlled through changing the substrate from synthetic glucose-rich wastewater to non-biodegradable wastewater.

[Experimental investigation of high saline wastewater treatment using aerobic granules].

Complete aerobic granulation could be achieved in shaking sequencing batch reactors (SSBR) with saline wastewater respectively inoculated conventional activated sludge and anaerobic granules. Pretty good specific TOC removal rates could be achieved without inoculating the halo-bacteria at the start-up time. When the salinity was less than 10 g/L NaCl with the synthetic glucose-rich wastewater as substitute, the TOC removal efficiency was in the range of 70.3%-97.6%. After the salinity was 35 g/L NaCl and the influent was completely changed to Vc wastewater as substrate, similar TOC removal efficiency about 70% could be achieved compared with the performance of fresh Vc wastewater treatment under the same condition. The granules in saline wastewater had a diameter of 0.5-3 mm, and saline aerobic granules had much higher settling velocity, higher oxygen utilization rate (OUR), lower sludge production and better structural integrity than those of the granules from fresh wastewater. Saline aerobic granules showed perfect protecting-ability against the saline shock and could quickly recover from long term sharp saline change. Due to the different sludge inoculation, the aerobic granules from aerobic flocs had superior TOC removal performance and inferior saline shock protecting-ability compared with the aerobic granules from anaerobic granules.

[Experimental investigation of aerobic granule cultivation in high strength Vc wastewater].

Aerobic granular sludge was cultivated in sequencing batch reactors (SBRs) fed with high strength and refractory real Vc wastewater. In the reactor treated transformation residues, it was achieved a completely aerobic granulation, and the sludge was 0.2-1 mm in diameter, average settling velocity 31.2 m x h(-1). In another reactor treated refinery or extracted residue, partially granular formation was reached, and the sludge was 0.5-2.5 mm in diameter, average settling velocity 26.3 m x h(-1). The formation of good aerobic granules contributed a good operational property. When influent COD was 1,000-1,500 mg x L(-1), COD removal efficiency was maintained approximately 80%. It could be improved better by adding biodegradable organic matters in feed. Through microscopic observation of sludge from two different reactors, the protozoa and biodiversity of microorganisms in reactors were determined not only by the operational parameters, but also by the influent composition. The granulation process in the experiment was proceeded through three stages, i. e. sludge activation phase, acclimatization phase and aerobic granulation phase. In operation control, the settling-time was used as the key factor for the formation of aerobic granules, which could decant the flocculent sludge and regulate the organic loading, and eventually promote the granulation process.