Nutrient removal has become one of the key challenges for wastewater treatment facilities all over the world due to the harmful effect of these pollutants on water bodies and ecosystems known by eutrophication, however, most of the currently used technologies are not focused on nutrients recovery from wastewater. Recently, using agricultural waste/by-products for adsorption of nutrients acquired more interest because of their abundant availability, low-cost, high efficiency and eco-friendly advantages and this method may become more environmentally sustainable through maximizing removal while delivering nutrient and energy recovery technologies with economically attractive return on investment.
This review investigates the application of agricultural waste/by-products as bio-sorbent for phosphate, ammonium and nitrate removal with a focus on the modification methods and the process mechanism including influent parameters, kinetics and isotherms.
Wastewater issues became a complex challenge in the world. There are several methods in wastewater treatment, such as chemical, physical, biological, and the combination of each method. However, each process has advantages and disadvantages. The physicochemical methods are common methods used in wastewater treatment, such as adsorption and coagulation. Adsorption and coagulation are excellent methods to remove pollutants. The adsorption process is greatly influenced by pH, adsorbent dose, temperature, and contact time. Coagulant dose, settling time, and pH are the main factors in the coagulation process. Chemical material as an adsorbent and coagulant has been studied in previous research, but recently, to substitution chemical materials is a challenging subject. Natural substances are potential new materials in wastewater treatment and became popular due to their efficiency and environment friendly characteristics. This review investigated the role of adsorption and coagulation in wastewater treatment and the utilization of natural materials as adsorbents and coagulants.
In this study the performance of a vibratory shear-enhanced processing system (VSEP) for the concentration of cheese whey was assessed and compared with a classical, cross-flow, plate and frame membrane configuration system (3DTA) with the same membrane (i.e. a C30F UF regenerated cellulose UF membrane with a 30 kDa molecular weight cutoff). The temperature and pressure dependences of the permeate flux, the permeate flux reduction ratio, the resistances and the rejection values were investigated. Comparison of the two systems revealed a definite advantage for the VSEP system equipped with the same membrane and operated at the same pressure and temperature. The VSEP system yielded a permeate protein retention of 99.7% vs. 74.5% for the 3DTA system, together with a higher average flux: 54 L m
vs. 44.2 L m
. The flux reduction ratio (
) was 0.60 vs. 0.42, and the total resistances 2.87*10
for the VSEP and 3DTA system, respectively.
Extraction of pectic substances from solid agro-wastes and the application of recovered pectin in the food, pharmaceutical and cosmetic industry can significantly contribute to a more economic and environmentally sound agro-industrial production. Thus investigation of the physicochemical properties of extracted pectic substances seems important not only from human health preservation considerations, but their advantageous properties can be confirmed for the possible manufacturers, potential processing, as well. Therefore, in this work pectic substances were extracted from red currant, black currant, raspberry, blackberry and elderberry press residues by hot water and the composition, antioxidant activity, total phenol, anthocyanin content and the color coordinates of pectins were determined. The results show that the pectin colors fall in the range between reddish purple (black currant and elderberry) and yellow (citrus and apple). Moreover some of the pectins in a powder form have different color coordinates than in the form of aqueous solutions or gels. This might be very important when the pectins are selected for different production processes. The anthocyanin content of pectin preparations is lower than the values of fruit juices. It can be concluded that the colorants found in pectin preparations belong to the group of phenolics and have adequate antioxidant capacity, which is extremely beneficial for human health. As a summary it was concluded that the investigated pectins can be easily extracted and successfully used as natural colorants or antioxidants since they have adequate antioxidant activity, total phenol and anthocyanin content and suitable color coordinates.
Membrane separation processes are currently proven technologies in many areas. The main limitation of these processes is the accumulation of matter at the membrane surface which leads to two phenomena: concentration polarization and membrane fouling. According to the publications of numerous authors permeate flux could be increased by sonication. Our work focuses on separation of real broth by sonicated ultrafiltration. The broth was originated from hydrolysis of grounded corn-cob by xylanase enzyme. The filtration was carried out in a laboratory batch stirred cell with a sonication rod sonicator. In our work the effect of the stirring, the intensity of sonication and the membrane-transducer distance was studied on the efficiency of the ultrafiltration and on the quality of separated enzymes. Results reveal that xylanase enzyme can be effectively separated from real fermentation broth by ultrafiltration and enzymes keep their activity after the process. Enzyme activity tests show that low energy sonication is not harmful to the enzyme.
To meet the requirements defined by environmental protection regulations effective wastewater treatment is required to process effluents before discharging them into sewers or living waters. While membrane separation offers a quite advantageous method to reduce the organic load of wastewaters, membrane fouling is still limiting its application in wastewater treatment.
In this study, the possibility of membrane fouling reduction by increased shear rates on the surface of the membrane was investigated. 7 and 10 kDa MWCO ultrafiltration and 240 Da nanofiltration membranes were studied, with the use of a laboratory mode Vibratory Shear Enhanced Processing. This work mostly focused on studying the effects of module vibration and recirculation feed flow rate on permeate flux, specific energy demand and membrane rejections. Using the same operation parameters, vibration and non-vibration mode experiments were carried out with high and low recirculation flow rate to have a deeper understanding of the shear rate effects. It can be concluded that higher shear rate had a positive effect on the process: increased shear rate resulted in higher flux, higher overall rejection values, as well as a significantly decreased specific energy demand. By calculating and comparing the shear rates in experiments with different operating parameters, both vibration and nonvibration mode, both low and high recirculation flow rate, we have reached the conclusion that vibration causes a significantly higher shear rate increase than setting the recirculation flow rate high.