John J. Ambuchi

Response of anaerobic granular sludge to iron oxide nanoparticles and multi-wall carbon nanotubes during beet sugar industrial wastewater treatment

The accelerated use of iron oxide nanoparticles (IONPs) and multi-wall carbon nanotubes (MWCNTs) in the consumer and industrial sectors has triggered the need to understand their potential environmental impact. The response of anaerobic granular sludge (AGS) to IONPs and MWCNTs during the anaerobic digestion of beet sugar industrial wastewater (BSIW) was investigated in this study. The IONPs increased the biogas and subsequent CH4 production rates in comparison with MWCNTs and the control samples. This might be due to the utilization of IONPs and MWCNTs as conduits for electron transfer toward methanogens. The MWCNTs majorly enriched the bacterial growth, while IONP enrichment mostly benefitted the archaea population. Furthermore, scanning electron microscopy and confocal laser scanning microscopy revealed that AGS produced extracellular polymeric substances, which interacted with the IONPs and MWCNTs. This provided cell protection and prevented the nanoparticles from piercing through the membranes and thus cytotoxicity. The results provide useful information and insights on the adjustment of anaerobic microorganisms to the natural complex environment based on nanoparticles infiltration.

A combined microbial desalination cell and electrodialysis system for copper-containing wastewater treatment and high-salinity-water desalination

A new concept for heavy metal removal by forming hydroxide precipitation using alkalinity produced by microbial desalination cell (MDC) was proposed. Four five-chamber MDCs were hydraulically connected to concurrently produce alkalinity to treat synthetic copper-containing wastewater and salt removal. There was nearly complete removal of copper, with a maximum removal rate of 5.07kg/(m3d) under the initial copper concentration of 5000mg/L (final pH of 7). The final copper concentration met the emission standard for electroplating of China (0.5mg/L, GB 21900-2008). XRD analysis indicated copper was precipitated as Cu2Cl(OH)3. The best performance of MDCs in terms of average power density, salt removal and COD removal rate achieved in stage 3 were 737.3±201.1mW/m2, 53.6±0.8kg/(m3d), and 1.84±0.05 kgCOD/(m3d) respectively. For purposes of water recovery, an electrodialysis (ED) system was presented based on in-situ utilization of generated electricity by MDCs as post-desalination treatment for salt effluent after sedimentation. The maximum discharging voltage of 12.75±1.26V at switching time (Ts) of 15min using a capacitor-based circuit produced a maximum desalination efficiency of 30.4±2.6%. These results indicated that this combined system holds great promise for real-world treatment of copper-containing wastewater and deep desalination of high-salinity-water.

Cascade degradation of organic matters in brewery wastewater using a continuous stirred microbial electrochemical reactor and analysis of microbial communities.

A continuous stirred microbial electrochemical reactor (CSMER), comprising of a complete mixing zone (CMZ) and microbial electrochemical zone (MEZ), was used for brewery wastewater treatment. The system realized 75.4 ± 5.7% of TCOD and 64.9 ± 4.9% of TSS when fed with brewery wastewater concomitantly achieving an average maximum power density of 304 ± 31 m W m−2. Cascade utilization of organic matters made the CSMER remove a wider range of substrates compared with a continuous stirred tank reactor (CSTR), in which process 79.1 ± 5.6% of soluble protein and 86.6 ± 2.2% of soluble carbohydrates were degraded by anaerobic digestion in the CMZ and short-chain volatile fatty acids were further decomposed and generated current in the MEZ. Co-existence of fermentative bacteria (Clostridium and Bacteroides, 19.7% and 5.0%), acetogenic bacteria (Syntrophobacter, 20.8%), methanogenic archaea (Methanosaeta and Methanobacterium, 40.3% and 38.4%) and exoelectrogens (Geobacter, 12.4%) as well as a clear spatial distribution and syntrophic interaction among them contributed to the cascade degradation process in CSMER. The CSMER shows great promise for practical wastewater treatment application due to high pre-hydrolysis and acidification rate, high energy recovery and low capital cost.

Trends in indoor–outdoor PM2.5 research: A systematic review of studies conducted during the last decade (2003–2013)

There has been growing concern about potential health risks from exposure to PM2.5 (fine particulate matter). The importance of conducting simultaneous indoor and outdoor measurements emerged because people, especially in developed countries, spend more than 90% of their time indoors. Great spatial and temporal variations in human exposure to PM2.5 have recently been reported. This review aims to identify the main research areas that have attracted recent attention, any possible gaps in the measurements of PM2.5 in various microenvironments, and the relationships between indoor and outdoor concentrations. This study also provides recommendations for further studies on PM2.5 measurement methods and exposure levels. To achieve these goals, this review included articles published online from 2003 to 2013 in the Science Direct and Web of Science databases. In the initial screening stage, 113 abstracts selected while 61 articles were remained for full review. The reviewed studies consistently showed positive correlations between indoor and outdoor PM2.5. Sulfate/sulfur concentrations were used intensively for calculating the infiltration factor (FINF). The higher FINF indicated high infiltration of outdoor PM2.5 into indoor areas. Great percentage (42%) of the reviewed filter–based studies was conducted in Europe, followed by a similar amount (38%) in the USA, and 20% in Asia, indicating a lack in PM2.5 research in other parts of the world. It was difficult to conclude that ambient fixed–site monitoring provided accurate estimations of actual exposure to PM2.5– Studies shown trends of higher personal concentrations compared to indoor and outdoor ones. Higher indoor levels of OC (organic carbon), compared to outdoor levels, were consistently reported. The opposite trend was true for EC (elemental carbon), and there were higher indoor OC/EC ratios than outdoor OC/EC ratios. There was a consistent general trend of a high (r>0.70) correlation between indoor and outdoor EC, while the correlation between indoor and outdoor OC was much weaker (r=022–0.75). The higher indoor OC/EC ratios, compared to the outdoor OC/EC ratios, reflects multiple sources of indoor OC. Sulfate (SO42–), nitrate (NO3–), and ammonium (NH4+) were primary contributors to PM2.5 mass.

Potential Toxicological and Cardiopulmonary Effects of PM2.5 Exposure and Related Mortality: Findings of Recent Studies Published during 2003-2013.

Air pollution has become a serious environmental issue owing to its diverse harmful effects on the physical and biological environment. According to the Environmental Protection Agency (EPA) and the World Health Organization (WHO), air pollution affects millions of people worldwide. Hundreds of thousands of deaths each year and a range of diseases, particularly among vulnerable groups (i.e., children, the elderly, and people with special medical conditions), are attributed to air pollution. These effects are not always caused by single pollutant in the air; rather, they are considered consequences of the multi-pollutants to which people are simultaneously exposed. The chemical composition, the degree (rate) of exposure, and the morphology of the particles are major factors influencing the type of potential adverse effects. The exposure to fine particulate matter (PM2.5) in urban areas is quite complicated where the variety of residential, commercial, and industrial sources contribute differently to the total PM2.5 mass concentrations and its associated chemical constituents. Taking into consideration the aforementioned health effects of PM2.5 exposure, whether the reported effects were consistent across different studies or not still need further research. Additionally, a wide spectrum of short-term biological responses to PM2.5 exposure has been reported, but it is difficult to link them to specific chronic effects. The aims of our current review are to compile all of the possible effects that may show linear or obvious associations with the exposure to fine particles, or its constituents, and determine possible discrepancies in the obtained results. SEARCHING METHOD

Simultaneous algae-polluted water treatment and electricity generation using a biocathode-coupled electrocoagulation cell (bio-ECC)

How to utilize electrocoagulation (EC) technology for algae-polluted water treatment in an energy-efficient manner remains a critical challenge for its widespread application. Herein, a novel biocathode-coupled electrocoagulation cell (bio-ECC) with sacrificial iron anode and nitrifying biocathode was developed. Under different solution conductivities (2.33±0.25mScm-1 and 4.94±0.55mScm-1), the bio-ECC achieved almost complete removal of algae cells. The maximum power densities of 8.41 and 11.33Wm-3 at corresponding current densities of 48.03Am-3 and 66.26Am-3 were obtained, with the positive energy balance of 4.52 and 7.44Wm-3. In addition, the bio-ECC exhibited excellent NH4+-N removal performance with the nitrogen removal rates of 7.28mgL-1h-1 and 6.77mgL-1h-1 in cathode chamber, indicating the superiority of bio-ECC in NH4+-N removal. Pyrosequencing revealed that nitrifiers including Nitrospira, Nitrobacter, Nitrosococcus, and Nitrosomonas were enriched in biocathode. The removal mechanisms of algae in anode chamber were also explored by AFM and SEM-EDX tests. These results provide a proof-of-concept study of transferring energy-intensive EC process into an energy-neutral process with high-efficiency algae removal and electricity recovery.