Search

The implementation of latest International Maritime Organization (IMO) emission standard has raised stringent nitrogen requirements for marine domestic sewage discharge. In order to meet new discharge standards, novel aerobic-anaerobic micro-sludge membrane bioreactor (O-AMSMBR) for chemical oxygen demand (COD) and total nitrogen (TN) removal from ship sewage is proposed. Results indicated that novel MBR achieved better COD and TN removal efficiency (Ravg(COD) = 91.6% and Ravg(TN) = 88.07%). The amount of anaerobic sludge in O-AMSMBR was reduced by 80% however TN removal rate was 10% higher than traditional Membrane Bio-Reactors (MBRs) technology. Based on the analysis of sludge characteristics, high TN removal efficiency is achieved via collective role of simultaneous nitrification and denitrification (SND) and “anaerobic micro-sludge effect”. Microbial community analysis also revealed that Rhodobacter and Pseudomonas are dominant species in anaerobic zone, which has a direct relationship with “anaerobic micro-sludge effect”. Further, transmembrane Pressure (TMP) showed that “anaerobic micro-sludge effect” not only has a positive effect on pollutants removal but also can suspend membrane fouling. The outcomes of this study suggest that post-anaerobic integrated with micro-sludge methods played a vital role in keeping good pollutant degradation in ship wastewater treatment. The presented results can provide new insights into ship sewage treatment by MBR technology.

The implementation of the latest International Maritime Organization (IMO) emission standard has raised stringent requirements for marine domestic sewage discharge. In this study, a novel aerobic-anaerobic micro-sludge membrane bioreactor (O-AMSMBR) was used to analyze the effect of pH variation on the effluent chemical oxygen demand (COD) and total nitrogen (TN) for marine domestic sewage. Results showed that the novel MBR achieved better COD and TN removal efficiency (Ravg(COD) = 87.77% and Ravg(TN) = 91.01%). In acid environment (pH = 5), anaerobic micro-sludge MBR technology can enhance the pollutants removal efficiency under pH shock. These two findings indicated that anaerobic micro-sludge membrane bioreactor (MBR) technology has great potential in acidity or alkalinity wastewater treatment. The activity of six different enzymes was analyzed in this study. The results showed that nitrate reductase and nitrite reductase can serve as special indicating factors for anaerobic micro-sludge MBR technology on domestic ship sewage. Moreover, wavelet neural network (WNN) and back-propagation neural network (BPNN) were used to simulate the effect of pH on reactor performance. The order of relative importance inculcated that pH is the key factor to consider for biodegradation of organic matter in O-AMSMBR system. The outcomes of this study suggest that post-anaerobic integrated with micro-sludge methods can play a vital role in keeping good pollutant degradation in ship wastewater treatment under pH shift.

Recently, strict standards for ship domestic sewage discharge have been implemented by the International Maritime Organization (IMO). The high salinity of ship sewage was considered a key factor influencing the removal efficiency of ship sewage treatment systems. In the present study, the salinity effect on the removal of chemical oxygen demand (COD) and ammonia nitrogen (NH4+-N) from ship domestic sewage was investigated by using a novel air-lift multilevel circulation membrane reactor (AMCMBR). Enzyme activity analysis and wavelet neural network (WNN) models were built to determine the mechanisms of the process. The experimental results indicate that high salinity levels (> 21 g/L) had a negative impact on COD and NH4+-N removal efficiencies, and low saline concentrations (≤ 21 g/L) caused a negligible effect. The COD and NH4-N removal efficiencies were 84% and 97%, respectively, at a salinity of 21 g/L, which were higher than those at low salinities (i.e., 7 g/L and 14 g/L). Invertase and nitrate reductase had a close relationship with removal performance, and they can be considered important indicators reflecting the operation effort under saline environments. With high predictive accuracies, the constructed WNN models simulated the complex COD and NH4+-N removal processes well under different saline concentrations, ensuring the long-term stable operation of the AMCMBR under different salinities.

Developing a real ship sewage treatment system that not only satisfies the requirement of small space onboard but also meets the latest emission standards of International Maritime Organization (IMO) is still a challenging task for ship industry. To overcome these problems, in this study, a novel pilot-scale air-lift multilevel circulation membrane bioreactor (AMCMBR) was used to explore the effect of hydraulic retention time (HRT) on effluent chemical oxygen demand (COD) and total nitrogen (TN) while treating real ship sewage. Results indicated that the satisfactory removal efficiencies of COD and TN was achieved in the former stages (Re(COD) = 91.57% and 87.82%; Re(TN) = 77.17% and 81.19%). When HRT decreased to 4 h, the removal efficiencies of COD and TN was 86.93% and 70.49% respectively, which still met the strict IMO discharge standards. This mainly because the biofilm-assistant membrane filtration lead to the increase of physical removal rate. The high ratio of mixed liquor volatile suspended solids (MLVSS)/mixed liquid suspended solids (MLSS) (i.e. 0.75) indicated a high biomass content in the attached sludge and resulted into perfect pollutants removal effort. The compliance rate of COD and TN was 100% and 89%, respectively, which indicated stable operation of the pilot-scale AMCMBR throughout the whole experiment. Fluorescence in situ Hybridization (FISH) analysis revealed that the abundance of β-Proteobacteria was a key microbial reason for TN removal. In addition, wavelet neural network (WNN) model was proved to be suitable to simulate and predict the COD and TN removal. These conclusions indicated that the pilot-scale AMCMBR technology is an effective way for real ship sewage treatment.

e24186Background: Tumor Mutation Burden (TMB) is an effective genomic biomarker to predict the efficacy of anti PD-L1/PD1 therapies. WES is a general method to detect the TMB in scientific studies ...

e24188Background: With the development of the next-generation sequencing, the tumor mutation detection is more extensive. Generally, it uses non-tumor tissue to distinguish somatic and germline mut...

7070Background: Somatic SNVs/indels and clonal mosaicism in blood of individuals free of hematological malignancies has been previously characterized, but were reported with a low frequency ( < 3%)...