This paper presents a comprehensive literature review of different characteristics of greywater (GW) and current treatment methods. GW is domestic wastewater excluding toilet waste and can be classified as either low-load GW (excluding kitchen and laundry GW) or high-load GW (including kitchen and/or laundry). This review provides information on the quantity of GW produced, its constituents (macro and micro), existing guidelines for wastewater reuse, current treatment methods (from storage to disinfection) as well as related costs and environmental impacts. Moreover some successful examples from various countries around the world are examined. The current preferred treatments for GW use physical and biological/natural systems. Recently, chemical systems like coagulation, adsorption and advanced oxidation processes (AOPs) have been considered and have been successful for low to moderate strength GW. The presence of xenobiotic organic compounds (XOC), which are hazardous micropollutants in GW, is emphasised. Since conventional treatments are not efficient at removing XOC, it is recommended that future studies look at chemical treatment, especially AOPs that have been found to be successful at mineralising recalcitrant organic compounds in wastewater.
In this study, the adsorptive effectiveness of sustainable and cost-effective eucalyptus bark biomass in the removal of methylene blue (MB) dye from its aqueous solution has been tested using a packed bed up-flow column experiment. A series of column experiments using raw eucalyptus bark was performed to determine the breakthrough curves with varying inlet MB dye flow rate (10-15 mL min -1 ), initial MB dye concentration (50-100 mg L -1 ) and adsorbent bed height (10-15 cm). High bed height, low flow rate and high initial dye concentration were found to be the better conditions for maximum dye adsorption. To predict the breakthrough curves and to determine the characteristic parameters of the column dynamics for industrial applications and for process design, Thomas model, Yoon-Nelson model and bed depth service time model were applied to experimental breakthrough data. All models were found suitable for describing the dynamic behaviour of the column, with respect to MB flow rate, initial dye concentration and adsorbent bed height. The findings revealed that eucalyptus bark biomass has a high adsorption potential for the removal of MB dye from aqueous solutions in a column system, and that it could be used to treat dye-containing effluents.
List of symbols ACross sectional area of bed in column (cm 2 ) A 1 Used bed area (cm 2 ) A 2 Unused bed area (cm 2 )pollutant concentration (mg/L) C o Inlet pollutant concentration (mg/L) H Height of bed in column (cm) H B Used bed length up to break point (cm) H T Bed height of column (cm) H UNB Unused bed length (cm) K o Rate constant in BDST model (L/mg min) K T Thomas rate constant (mL/mg min) K YN Yoon and Nelson rate constant (min -1 ) MTZ Mass transfer zone (cm) m Amount of adsorbent in the column (g) m p Mass of pine cone (g) m total Total amount of methylene blue dye sent to column (g) N o Adsorption capacity (mg/L) Q Volumetric flow rate (mL/min) q total Total adsorbed methylene blue dye quantity (g) q o Equilibrium adsorbate uptake (mg/g) t Breakthrough (sampling) time (min) t t Total time (min) t total Total flow time (min) t b Usable capacity of bed up to the breakthrough point time (min) t u Time equivalent to usable capacity (min) U Influent linear velocity (cm/min) V Effluent volume (ml) V eff Total effluent volume (mL) s Time required for 50 % adsorbate breakthrough (min)
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.