Advances in Environmental Technology
Volume:9 Issue: 4, Autumn 2023

This study investigated the adsorption of an azo dye called Congo red from aqueous solution. Ash prepared from sunflower seed waste was used as the adsorbent. Brunauer–Emmett–Teller (BET), Scanning electron microscopy (SEM), and Fourier-Transform Infrared spectroscopy (FT-IR) analyses were performed to characterize the prepared adsorbent. Based on the results of BET, the specific active surface area was about 102 m2/g, and the results of SEM indicated that the adsorbent surface had a very fine porosity that could be attributed to the presence of cellulosic materials in the adsorbent structure. In this study, the effect of the initial concentration of Congo red dye (10-50 mg/L), the concentration of adsorbent (1-5 g/L), and the processing time (10-240 min) on the rate of Congo red dye removal was investigated. The results showed that the highest percentage of dye removal, i.e., 92%, was achieved at a dye concentration of 50 mg/L, an adsorbent concentration of 3 g/L, and a processing time of 180 min. Under these conditions, the amount of adsorbed dye per gram of the adsorbent was 15.5 mg/g. In addition, pseudo-first order and pseudo-second order kinetic models were also used for modeling. The modeling results indicated that the pseudo-second order model had a higher level of accuracy. Finally, washing adsorbent with different solvents (one molar sodium hydroxide, double distilled water, and ethanol) was investigated, the results indicated that the adsorbent washed with one molar sodium hydroxide had a proper performance after five times of reuse.

BackgroundConventional techniques for water disinfection are fraught with issues like personnel exposure to damaging radiation and formation of harmful and carcinogenic disinfection byproducts. There are difficulties related to transportation and handling, and expensive capital and working costs also are involved like costs associated with on-site generation of disinfectants. There is a dire need for newer disinfection technologies that are environment and health friendly.Scope and benefitsThis article reviews the use of natural disinfectants derived from plants to enhance the quality of water. Researchers have utilized herbal extracts, phytochemicals, and phytochemical-metal complexes for the disinfection of water. Various factors for these chemicals like efficacy, toxicity, cost, and water solubility have been discussed and some useful phytochemical disinfectants are also identified. These disinfection methods particularly when using only pure phytochemicals are generally thought to be free from the deleterious effects associated with chlorination and other conventional technologies. Inherently, chlorinated and other harmful disinfection byproducts are not formed.Key findings and conclusionsIn various studies eugenol, thymol and extracts of Ocimum sanctum and Azadirachta indica have been utilized with fairly effective disinfection capabilities. The significant antimicrobial effects of allicin, berteroin, sanguinarine, and thymol are reflected from their very low minimum inhibitory concentration values. Even so, presently the efficiency of phytochemicals is not comparable to conventional disinfectants. The use of phytochemical metal complexes is, however, a plausible option that might be investigated further. The metal complexes because of their greater water solubility than pure phytochemicals result in improved disinfection efficiency. Notable among those are flavonoid-metal complexes that should be considered further for use in water disinfection. It is also concluded that phytochemicals may be added to water that has also been disinfected with some other commonly-used technology. A way to do this may be to design a fixed bed tower of phyto-disinfectant through which water should pass.

Research on the dispersion and deposition of solid particles in sanitation networks is crucial due to its role in channel blockage and overflow of wastewater and stormwater systems. Conventional detection methods are excessively costly and demand a significant time investment, while predictive mathematical models are prone to uncertainties. This study aims to assess the influence of solid particles on fluid flow and incorporate the effects of added mass and pressure gradient into the equation governing particle behavior. It is motivated by observations in Algeria, where the density of solid particles is notably high, thereby accentuating their impact on wastewater flows. To achieve these objectives, a bidirectional Eulerian-Lagrangian coupling method is employed, combining the advantages of various turbulence models, including the k-ω-sst model and the standard discrete random walk (DRW) model. This approach enhances our understanding of solid particle dispersion and deposition in sanitation networks, contributing to more efficient management and prevention of pipe obstructions, with implications for environmental preservation and the sustainability of urban sanitation systems. The use of turbulence models recommended in this study is inspired by Kolmogorov''s pioneering work on turbulence, while the integration of added mass and pressure gradient forces falls within the context of particle dynamics in suspension. By leveraging in-situ data and incorporating the aforementioned forces, this innovative approach deepens our understanding of the processes involved in solid particle dispersion and deposition in urban drainage networks. These advancements are pivotal for the management and prevention of pipe obstructions, thus contributing to the preservation of the environment and the sustainability of urban sanitation systems.

Thermal cracking of hydrocarbons at 850-900 degree centigrade is the governing technology worldwide for light olefins production. But the most disadvantages of this route is large energy consumption and air pollution because of flue gas emission containing CO2 and NOx. To overcome   these drawbacks catalytic cracking is an important and new field for research. So, in this work the effects of temperature and loadings of cerium and lanthanum over HZSM-5 catalyst for thermal catalytic cracking of naphtha were investigated using response surface methodology. In these experiments, the temperature, Ce, and La loadings were varied from 600 to 700 °C, 4 to 12wt.%, and 0.8 to 3wt%, respectively. The Box-Behnken design was utilized and a set of experiments were designed to obtain the optimum catalyst for maximizing the yield of ethylene and propylene. The analysis of variance (ANOVA) was carried out to identify the statistical significance of independent factors and their interactions. The results showed that temperature and Ce loading had the highest effects on the yields of ethylene and propylene, respectively. Based on the multi-objective optimization, the maximum yields of ethylene and propylene (17 and 33wt%, respectively) were obtained at cerium loading of 12 wt.%, lanthanum loading of 1.2 wt.%, and temperature of 700 °C

A lab based hybrid constructed wetland system (1.645 m2) consisting of sludge drying bed (0.135 m2), vertical sub-surface flow bed (0.58 m2), and horizontal sub-surface flow bed (0.93 m2) was operated for the treatment of septage. All the beds were filled with gravels of varied sizes (5-40 mm), sand (0.25 mm) and planted with Canna indica L. Average concentration in influent and effluent was observed as; BOD5 (2395.6±1196.4 and 41.87±8.9 mg/L), COD (7442± 7342.6 and 29.6±7.6 mg/L), TSS (4965.9±801.69 and 336.1±152.9 mg/L), TN (1774.8±693.5 and 55.7±13.7 mg/L), and Total P (849.3±237.7 and 7.05±3.5mg/L) during study period. Hybrid System was operated with high influent loads of BOD5 (175.2± 87.5 g m-2 d-1), COD (544.5±537 g m-2 d-1), TSS (363.3±58.6 g m-2 d-1), Total N (129.8±50.7 g m-2 d-1), NH4-N (7.8±1.1 g m-2 d-1), and Total P (62.1±17.4 g m-2 d-1), throughout the study period. Hybrid-CW has showed significant removal of BOD5 (99.1±0.3%), COD (99.7±0.3%), TS (98.2±6.8%), TSS (96.9±4.9%), Total N (98.4±0.4 %), NH4-N (94.8±0.1%), and Total P (99.6±0.1%) from the septage. Finally treated septage met effluent discharge standards for all parameters except BOD5.

The lab-scale treatment of strong beet sugar wastewater was carried out with a combination of a moving bed biofilm reactor (MBBR) and upflow sludge blanket filtration (USBF). The hybrid bioreactor was filled (35% of volume) with industrial packings made of polyethylene with an effective surface area of 480 m2/m3 to provide the necessary surface for biofilm growth. The effect of various operating conditions, including hydraulic retention time (HRT = 12-20 hr), biomass concentration (6000– 8000 mg/L), and initial chemical oxygen demand (COD) (3000-5000 mg/L) level, were assessed on the overall COD removal efficiency using response surface methodology (RSM). The optimal conditions were an HRT = 20 hr, biomass concentration = 8000 mg/L, an initial COD = 3000 mg/L, and an organic loading rate (OLR) of 3.6 kg COD/m3.day under which the COD removal efficiency was 98%. The modified Stover–Kincannon model was applied to predict the biokinetic coefficients for COD removal; the saturation constant (KB) and the maximum total substrate utilization rate (Umax) were in the range 58-101.6 and 57.5- 97 as g/L.day, respectively.  The results revealed that raising HRT or biomass concentration promoted COD removal while increasing the initial COD deteriorated the removal performance.