I. Norli

Extraction and recovery of methylene blue from industrial wastewater using benzoic acid as an extractant.

Liquid-liquid extraction (LLE) of methylene blue (MB) from industrial wastewater using benzoic acid (extractant) in xylene has been studied at 27 degrees C. The extraction of the dye increased with increasing extractant concentration. The extraction abilities have been studied on benzoic acid concentration in the range of 0.36-5.8x10(-2) M. The distribution ratio of the dye is reasonably high (D=49.5) even in the presence of inorganic salts. Irrespective of the concentration of dye, extraction under optimal conditions was 90-99% after 15 min of phase separation. The extracted dye in the organic phase can be back extracted into sulphuric acid solution. The resultant recovered organic phase can be reused in succeeding extraction of dye with the yield ranging from 99 to 87% after 15 times reused, depending on the concentration of the initial feed solution. Experimental parameters examined were benzoic acid concentration, effect of diluent, effect of pH, effect of initial dye concentration, effect of equilibration time, various stripping agents, aqueous to organic phase ratio in extraction, organic to aqueous phase ratio in stripping and reusability of solvent.

Characterization of biopolymeric flocculant (pectin) and organic synthetic flocculant (PAM): A comparative study on treatment and optimization in kaolin suspension

Polyacrylamide (PAM), a commonly used organic synthetic flocculant, is known to have high reduction in turbidity treatment. However, PAM is not readily degradable. In this paper, pectin as a biopolymeric flocculant is used. The objectives are (i) to determine the characteristics of both flocculants (ii) to optimize the treatment processes of both flocculants in synthetic turbid waste water. The results obtained indicated that pectin has a lower average molecular weight at 1.63 x 10(5) and PAM at 6.00 x 10(7). However, the thermal degradation results showed that the onset temperature for pectin is at 165.58 degrees C, while the highest onset temperature obtained for PAM is at 235.39 degrees C. The optimum treatment conditions for the biopolymeric flocculant for flocculating activity was at pH 3, cation concentration at 0.55 mM, and pectin concentration at 3 mg/L. In contrast, PAM was at pH 4, cation concentration >0.05 mM and PAM concentration between 13 and 30 mg/L.

Impacts of trace element supplementation on the performance of anaerobic digestion process: A critical review

This paper critically reviews the impacts of supplementing trace elements on the anaerobic digestion performance. The in-depth knowledge of trace elements as micronutrients and metalloenzyme components justifies trace element supplementation into the anaerobic digestion system. Most of the earlier studies reported that trace elements addition at (sub)optimum dosages had positive impacts mainly longer term on digester stability with greater organic matter degradation, low volatile fatty acids (VFA) concentration and higher biogas production. However, these positive impacts and element requirements are not fully understood, they are explained on a case to case basis because of the great variance of the anaerobic digestion operation. Iron (Fe), nickel (Ni) and cobalt (Co) are the most studied and desirable elements. The right combination of multi-elements supplementation can have greater positive impact. This measure is highly recommended, especially for the mono-digestion of micronutrient-deficient substrates. The future research should consider the aspect of trace element bioavailability.

Evaluation of the effect of temperature, NaOH concentration and time on solubilization of palm oil mill effluent (POME) using response surface methodology (RSM)

In this study, palm oil mill effluent (POME) was solubilized by batch thermo-alkaline pre-treatments. A three-factor central composite design (CCD) was applied to identify the optimum COD solubilization condition. The individual and interactive effects of three factors, temperature, NaOH concentration and reaction time, on solubilization of POME were evaluated by employing response surface methodology (RSM). The experimental results showed that temperature, NaOH concentration and reaction time all had an individual significant effect on the solubilization of POME. But these three factors were independent, or there was insignificant interaction on the response. The maximum COD solubilization of 82.63% was estimated under the optimum condition at 32.5 degrees C, 8.83g/L of NaOH and 41.23h reaction time. The confirmation experiment of the predicted optimum conditions verified that the RSM with the central composite design was useful for optimizing the solubilization of POME.

Removal of heavy metals and antibiotics from treated sewage effluent by bacteria

The increased loads of antibiotics and heavy metals in sewage lead to bacterial cells acquiring resistance to both heavy metals and antibiotics. Therefore, these bacteria can play an important role for removal of pollutants from sewage. The utilization of the microbial processes such as biosorption and enzymatic biodegradation processes has increased during the recent years. These processes are significantly inexpensive and eco-friendly. Enzymatic techniques known as white biotechnology have the ability to degrade complex compounds. Hence, these can be applied to industrial processes. In the current review, the removal of heavy metals and antibiotics from treated sewage effluents by heavy metal/antibiotic-resistant bacteria will be discussed.

Optimization of nickel removal using liquid-liquid extraction and response surface methodology

Abstract The nickel extraction efficiency by means of liquid–liquid extraction (LLE) method was studied using response surface methodology; six parameters were identified as influential factors on nickel removal efficiency as the response. However, on screening experiments, only two factors were selected: pH and di-(2-ethylhexyl) phosphoric acid (D2EHPA) concentration. Face-centered composite design (FCCD) was applied in order to determine the optimum conditions for nickel removal by LLE. The results of FCCD showed that a second-order model described the relationship between the factors and nickel removal properly. Results showed that the optimum conditions are pH 1.1 and D2EHPA concentration 0.2 M, where 95.57% of nickel removal was achieved.

Potential of bacterial consortium for removal of cephalexin from aqueous solution

Abstract Antibiotics represent a global environmental problem due to their role in the increasing of antimicrobial resistance. Therefore, the removal of antibiotics from wastewater has received unrivalled attention in the recent years. Several technologies including the biodegradation process have been applied for this purpose. However, the potential of bacterial biomass in the biosorption of antibiotics has limited studies. The present study investigated cephalexin removal from aqueous solution by consortium bacterial cells (living and dead) which are tolerant for antibiotics. The factors including cephalexin, biomass, pH, temperature as well as presence of heavy metal ions were tested. The maximum biosorption efficiency was recorded at 0.4 mg L-1 (94.73% vs. 92.98% for living and dead cells respectively), dead cells exhibited more efficiency compared to living cells at 5 mg L-1 (82.36% vs. 46.66% respectively). Living cells are more effective at pH value between pH 4 and 6 (71.95–68.90%). The maximum removal of living cells was highest at 30 °C (80.26%), while was at 25 °C of dead cell biomass (63.81%). Remarkable percentage for cephalexin biosorption by living cells was recorded in the presence low concentrations of Ni2+ (0.21 mg L-1, 40% vs. 30% of living and dead cells, respectively). Living cells exhibited 27.42% and 25% of the removal with Cu2+ (1 mg L-1) and Pb2+ (0.4 mg L-1) respectively. In conclusion the bacterial cells biomass has a potential to remove cephalexin with some negative effects of heavy metals which can be overcome by the removal of these metal ions first and then removal of antibiotics in a second cycle.

A Review on Biofuel and Bioresources for Environmental Applications

Microalgae are considered one of the most promising feedstocks for biofuels. Interest in algae-based biofuels and chemicals has increased over the past few years because of their potential to reduce the dependence on crude oil-based fuels and chemicals. Algae is the most suitable and sustainable feedstock for producing green energy. However, numerous challenges associated with declining fossil fuel reserves as energy sources have accounted for a shift to biofuels as alternative product from algae. Algae is a source for renewable energy production since it can fix the greenhouse gas (CO2) by photosynthesis and does not compete with the production of food. This chapter, therefore, presents a review on the prospects of algae for biofuel production and also highlighted in this article is the macroalgae-based biofuels energy products obtained from algae as the raw biomass. In a nutshell, algae are the most sustainable fuel resource in terms of environmental issues.

Analysis and optimization of flocculation activity and turbidity reduction in kaolin suspension using pectin as a biopolymer flocculant

The performance of pectin in turbidity reduction and the optimum condition were determined using Response Surface Methodology (RSM). The effect of pH, cations concentration, and pectins dosage on flocculating activity and turbidity reduction was investigated at three levels and optimized by using Box-Behnken Design (BBD). Coagulation and flocculation process were assessed with a standard jar test procedure with rapid and slow mixing of a kaolin suspension (aluminium silicate), at 150 rpm and 30 rpm, respectively, in which a cation e.g. Al(3+), acts as coagulant, and pectin acts as the flocculant. In this research, all factors exhibited significant effect on flocculating activity and turbidity reduction. The experimental data and model predictions well agreed. From the 3D response surface graph, maximum flocculating activity and turbidity reduction are in the region of pH greater than 3, cation concentration greater than 0.5 mM, and pectin dosage greater than 20 mg/L, using synthetic turbid wastewater within the range. The flocculating activity for pectin and turbidity reduction in wastewater is at 99%.

Utilization of Microorganisms for Biopurification of Wastewaters (Agricultural and Industrial): An Environmental Perspective

Microbial biotreatment of wastewaters is a concern in recent years. Discharge of toxic pollutants to wastewater collection systems has increased concurrently with society’s progressive industrialization. Although industrialization is inevitable, various devastating ecological and human disasters which have continuously occurred implicate industries as major contributors to pollution problems and environmental degradation of various magnitudes. Organic and inorganic substances which were released into the environment as a result of agricultural and industrial water activities lead to organic and inorganic pollution. It stands to reason that an effective treatment of these wastewaters is necessary. Microorganisms have been tested primarily as an approach for the removal of organic pollutants from wastewaters and have been proven effective at reducing chemical oxygen demand (COD) and toxicity. Biological treatment in the study provides some of the most viable options for the treatment of wastewaters. Microbial degradation of industrial wastewaters involving the application of a variety of microorganisms has demonstrated effective degradability of wastewaters which has attracted attention in recent time. The utilization of these microorganisms for bioremediation of toxic industrial wastewaters offers a very efficient tool for biopurification of contaminated effluents. Bacterial and fungal strains in this study have huge capability of treating wastewaters discharged from various industries. They are ubiquitous in nature and their adaptability to extreme conditions makes them good biodegraders. Their enzyme producing activity makes them effective decolorizers and they remove toxic metals by adsorption ultimately rendering the wastewaters more ecofriendly. Noteworthy, the bacterial and fungal biomasses present many assets for the biopurification of wastewaters.