Potential of Magnesium Chloride for Nutrient Rejection in Forward Osmosis

Wastewater may contain high levels of the nutrients: nitrogen and phosphorus. Excessive release of nutrients to the environment can cause severe environmental problem such as eutrophication leading to algal blooms, oxygen deficiency, and fish kills. The forward osmosis (FO) could be a choice of treatment. FO process presents the results of using four kinds of variation in concentration of magnesium chloride (MgCl2) as draw solution and the two kinds of commercial membranes for nutrient rejection in the same cross flow velocity at 0.25 m/s and temperature at 25°C. Nutrients consisting of nitrogen (nitrite, nitrate, and ammonium) and phosphorus (phosphate) in feed solution were successfully rejected with an efficiency of mostly more 95%. The water flux in membrane HTI-NW achieved lower 7.55 - 9.61 L/m2·hr than in membrane HTI-ES that exceeds until 13.58 - 15.10 L/m2·hr. The reverse solute in membrane HTI-NW is seemly constant along all concentration of DS MgCl2 that the chloride diffusion is slightly higher than magnesium. In membrane HTI-ES, the reverse solute of chloride was almost three times than that of magnesium. The concentration of MgCl2 plays a significant role in rejecting nutrients by the Donnan’s potential and the diffusion constant in low and high concentration of DS, respectively.

Response surface method for modeling the removal of carbon dioxide from a simulated gas using water absorption enhanced with a liquid-film-forming device

This paper presents the results from using a physical absorption process to absorb gaseous CO2mixed with N2using water by producing tiny bubbles via a liquid-film-forming device（LFFD）that improves the solubility of CO2in water.The influence of various parameters—pressure,initial CO2concentration,gas-to-liquid ratios,and temperature—on the CO2removal efficiency and its absorption rate in water were investigated and estimated thoroughly by statistical polynomial models obtained by the utilization of the response surface method（RSM）with a central composite design（CCD）.Based on the analysis,a high efficiency of CO2capture can be reached in conditions such as low pressure,high CO2concentration at the inlet,low gas/liquid ratio,and low temperature.For instance,the highest removal efficiency in the RSM–CCD experimental matrix of nearly 80%occurred for run number 20,which was conducted at 0.30 MPa,CO2concentration of 35%,gas/liquid ratio of 0.71,and temperature of 15℃.Furthermore,the coefficients of determination,R^2,were 0.996 for the removal rate and 0.982 for the absorption rate,implying that the predicted values computed by the constructed models correlate strongly and fit well with the experimental values.The results obtained provide essential information for implementing this method properly and effectively and contribute a promising approach to the problem of CO2capture in air pollution treatment.

Potential bioremediation of mercury-contaminated substrate using filamentous fungi isolated from forest soil

The use of filamentous fungi in bioremediation of heavy metal contamination has been developed recently. This research aims to observe the capability of filamentous fungi isolated from forest soil for bioremediation of mercury contamination in a substrate. Six fungal strains were selected based on their capability to grow in 25 mg/L Hg2＋-contaminated potato dextrose agar plates. Fungal strain KRP1 showed the highest ratio of growth diameter, 0.831, thus was chosen for further observation. Identification based on colony and cell morphology carried out by 18S rRNA analysis gave a 98% match to Aspergillusflavus strain KRP1. The fungal characteristics in mercury（II） contamination such as range of optimum pH, optimum temperature and tolerance level were 5.5-7 and 25-35℃ and 100 mg/L respectively. The concentration of mercury in the media affected fungal growth during lag phases. The capability of the fungal strain to remove the mercury（II） contaminant was evaluated in 100 mL sterile 10 mg/L Hg2＋-contaminated potato dextrose broth media in 250 mL Erlenmeyer flasks inoculated with 108 spore/mL fungal spore suspension and incubation at 30℃ for 7 days. The mercury（II） utilization was observed for flasks shaken in a 130 r/min orbital shaker （shaken） and non- shaken flasks （static） treatments. Flasks containing contaminated media with no fungal spores were also provided as control. All treatments were done in triplicate. The strain was able to remove 97.50% and 98.73% mercury from shaken and static systems respectively. A.flavus strain KRPI seems to have potential use in bioremediation of aqueous substrates containing mercury（II） through a biosorption mechanism.

Inactivation effect of pressurized carbon dioxide on bacteriophage Qβ and ΦX174 as a novel disinfectant for water treatment

The inactivation effects of pressurized CO2 against bacteriophage Qβ and ФX 174 were investigated under the pressure of 0.3-0.9 MPa, initial concentration of 107-109 PFU/mL, and temperature of 17.8℃-27.2℃. The optimum conditions were found to be 0.7 MPa and an exposure time of 25 min. Under identical treatment conditions, a greater than 3.3-log reduction in bacteriophage Qβ was achieved by CO2, while a nearly 3.0 log reduction was observed for phage ФX174. The viricidal effects of N2O （an inactivation gas with similar characteristics to CO2）, normal acid （HC1）, and CO2 treatment with phosphate buffered saline affirmed the chemical nature of CO2 treatment. The pumping cycle, depressurization rate, and release of intracellular substances caused by CO2 were its viricidal mechanisms. The results indicate that CO2 has the potential for use as a disinfectant without forming disinfection by-products.

Potential application of high pressure carbon dioxide in treated wastewater and water disinfection:Recent overview and further trends

Recently emerging disadvantages in conventional disinfection have heightened the need for finding a new solution. Developments in the use of high pressure carbon dioxide for food preservation and sterilization have led to a renewed interest in its applicability in wastewater treatment and water disinfection. Pressurized CO2 is one of the most investigated methods of antibacterial treatment and has been used extensively for decades to inhibit pathogens in dried food and liquid products. This study reviews the literature concerning the utility of CO2 as a disinfecting agent, and the pathogen inactivation mechanism of CO2 treatment is evaluated based on all available research. In this paper, it will be argued that the successful application and high effectiveness of CO2 treatment in liquid foods open a potential opportunity for its use in wastewater treatment and water disinfection. The findings from models with different operating conditions（pressure, temperature, microorganism, water content, media …） suggest that most microorganisms are successfully inhibited under CO2 treatment. It will also be shown that the bacterial deaths under CO2 treatment can be explained by many different mechanisms.Moreover, the findings in this study can help to address the recently emerging problems in water disinfection, such as disinfection by-products（resulting from chlorination or ozone treatment）.

Delignification of disposable wooden chopsticks waste for fermentative hydrogen production by an enriched culture from a hot spring

Hydrogen （H2） production from lignocellulosic materials may be enhanced by removing lignin and increasing the porosity of the material prior to enzymatic hydrolysis. Alkaline pretreatment conditions, used to delignify disposable wooden chopsticks （DWC） waste, were investigated. The effects of NaOH concentration, temperature and retention time were examined and it was found that retention time had no effect on lignin removal or carbohydrate released in enzymatic hydrolysate. The highest percentage of lignin removal （41%） was obtained with 2% NaOH at 100℃, correlated with the highest carbohydrate released （67 mg/gpretreated DWC） in the hydrolysate. An enriched culture from a hot spring was used as inoculum for fermentative H2 production, and its optimum initial pH and temperature were determined to be 7.0 and 50℃, respectively. Furthermore, enzymatic hydrolysate from pretreated DWC was successfully demonstrated as a substrate for fermentative H2 production by the enriched culture. The maximum H2 yield and production rate were achieved at 195 mL H2/g total sugarsconsumed and 1 16 mL Hz/（L.day）, respectively.