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Ha Manh Bui

Abstract

The COD removal efficiency from an instant coffee processing wastewater using electrocoagulation was investigated. For this purpose, the response surface methodology was employed, using central composing design to optimize three of the most important operating variables, i.e., electrolysis time, current density and initial pH. The results based upon statistical analysis showed that the quadratic models for COD removal were significant at very low probability value (<0.0001) and high coefficient of determination (R2 = 0.9621) value. The statistical results also indicated that all the three variables and the interaction between initial pH and electrolysis time were significant on COD abatement. The maximum predicted COD removal using the response function reached 93.3% with electrolysis time of 10 min, current density of 108.3 A/m2 and initial pH of 7.0, respectively. The removal efficiency value was agreed well with the experimental value of COD removal (90.4%) under the optimum conditions.

Open access

Bui Manh Ha

Abstract

The shortage of water resources influences the future sustainability of sticky Maize (Zea mays L.) production. Deficit irrigation (DI) - a water management strategy - has gained much attention from scientists because of enhanced water use efficiency (WUE). Nonetheless, in reality, when applying this technique, its impact on yield and economic returns should be considered. Through an analytical literature review, this study examined the effect of growth stage DI on Maize production factors, i.e. yield, WUE, and economic returns. The results revealed that Maize’s WUE could be improved with the lowest reduction in yield as water stress was imposed during the vegetative or maturation growth stages. Therefore, the profitable returns could be reached even if the yield was reduced; however, the economic return was sensitive to commodity prices. The present review addressed that the Maize flexible capacities under growth stage water stress presented an opportunity for the optimization of irrigated water and profit preservation by accurately judging the managing time of irrigation implementation.

Open access

Cong Tien Nguyen, Ha Manh Bui and Duyen Hoang My Nguyen

Abstract

The A new benzothiazepine’s derivative names N-(p-tolyl)-2-(2-(4-phenyl-2,3-dihydrobenzo[b][1,4]thiazepin-2-yl)phenoxy)acetamide was synthesized by reaction of o-aminothiophenol and N-(p-tolyl)-2-(2-(3-oxo-3-phenylprop-1-en-1-yl)phenoxy)acetamide, which was prepared from salicylaldehyde and acetophenone through (E)-3-(2-hydroxyphenyl)-1-phenylprop-2-en-1-one. The structures of the compounds were determined by IR, 1H-NMR, 13C-NMR and HR-MS spectral data.

Open access

Bui Manh Ha, Duong Thi Giang Huong and Luong Thi Hong Xuyen

Abstract

Traditional markets play a major role in socio-economics and constitutes a significant aspect of Vietnamese culture. However, wastewater streams discharged from the markets are generally characterized by a lot of inorganic nutrients and organic substances originated from fresh food processing units. They could lead to serious water contamination if discharged without proper treatment. This study applied microalgae Chlorella sp. for eliminating inorganic nutrients (NO3 -N, NH4 +-N and PO4 3−-P) and organic carbon (Chemical oxygen demand-COD) from wastewater of the Binh Dien market. The removal efficiencies reached for NH4 +-N > 86%, for NO3 -N > 72%, and for PO4 3−-P > 69%, respectively, at algal density of 49 × 104 cell mL−1, and for COD > 96% at algal density of 35 × 104 cell mL−1 after five cultivating days. The effluence satisfied the Vietnamese standard, column B, of the National technical regulation on industrial wastewater (QCVN 40:2011/BTNMT). The results demonstrated that the culture system composed of green algal Chlorella sp. could be a potential candidate for the removal of nutrients and organic carbon by a wastewater treatment process from the Binh Dien market.

Open access

Bui Manh Ha and Duong Thi Giang Huong

Abstract

In this study, wastewater taken from the Nam Phong swine slaughterhouse, Ho Chi Minh City, was used to evaluate the treatment efficiency of common coagulants, including Alum (Aluminum Sulfate - Al2(SO4)3.18H2O), Poly-Aluminum Chloride (PAC), and Ferrous Sulfate (FeSO4.7H2O), using a jar-test system. The experiments were conducted using the one-factor-at-a-time method to examine three variables which are pH, stirring speed, and coagulant dosage. The results showed that both Alum and PAC perform over 90% removal of colour, turbidity, COD, and total phosphorus (TP) from slaughterhouse wastewater at pH 7 with a stirring speed of 75 revolutions per minute (RPM) and average coagulant dosages of 450 mg/L for Alum and 550 mg/L for PAC. Meanwhile, under the appropriate conditions of pH equal to 10 and 75 RPM with a chemical dosage of 350 mg/L, COD and TP removal efficiencies by Ferrous Sulfate exceed 87%, but those of turbidity and colour only reach 25%. This finding could be a promising coagulation method as a pre-treatment for the swine slaughterhouse wastewater.