Review of the technological approaches for grey water treatment and reuses
ABSTRACT Based on literature review, a non-potable urban grey water reuse standard is proposed and the treatment alternatives and reuse scheme for grey water reuses are evaluated according to grey water characteristics and the proposed standard. The literature review shows that all types of grey water have good biodegradability. The bathroom and the laundry grey water are deficient in both nitrogen and phosphors. The kitchen grey water has a balanced COD: N: P ratio. The review also reveals that physical processes alone are not sufficient to guarantee an adequate reduction of the organics, nutrients and surfactants. The chemical processes can efficiently remove the suspended solids, organic materials and surfactants in the low strength grey water. The combination of aerobic biological process with physical filtration and disinfection is considered to be the most economical and feasible solution for grey water recycling. The MBR appears to be a very attractive solution in collective urban residential buildings.
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- "However many of the high technology wastewater treatment systems are not suitable for developing countries since they require high initial investment, consistent power supply and skilled labor for operation and maintenance . On the other hand, constructed wetlands, which depend on natural processes for pollutant removal have been considered as a promising environment friendly option and cost effective technology for greywater treatment and reuse . The treatment efficiency of constructed wetlands is supposed to be higher in tropical countries due to the warm temperature and associated higher rate of microbial activities and plant growth. "
ABSTRACT: The scarcity of freshwater has emerged as one of the most pressing problems of the 21st century. This problem could be addressed partially by collection, treatment and reuse of greywater. In this context, constructed wetlands (CWs) become attractive due to their simple mode of operation, effectiveness in treatment and applicability at small/single household levels as well as in community levels. Hence the present study investigates the treatment of greywater in a laboratory scale horizontal sub-surface flow constructed wetland planted with Axonopus compressus (Sw.) P. Beauv. – a common landscape plant. The experiment was conducted for a period of 50 days with change in wastewater every 10 days (1 run). During each run the wastewater was circulated using a peristaltic pump at an HRT of 7.8 h. The results show that CWs planted with A. compressus performed well in the treatment of greywater than the unplanted control with an average removal of 93% turbidity, 95% COD, 98% NO3−–N, 67% PO43−–P, and 95% of anionic surfactants. The plant also survived well with increase in biomass and number during the experiment and proved to be an efficient bioagent suitable for the treatment of greywater in CWs. The study further suggests that the use of commercially valuable ornamental plants in the CWs as bioagents will improve the aesthetic beauty, public acceptance and help to generate revenue apart from the major benefit of wastewater treatment.
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- "Technologies applied for greywater treatments include physical , chemical, and biological methods. Most of these technologies are preceded by a solid–liquid separation step as pre-treatment and followed by a disinfection step as a post-treatment  . Reported methods are aerobic treatment coupled with UV, ozone or chlorine disinfection, anaerobic digestion, adsorption on active carbon, photooxidation (UV/H 2 O 2 ), microfiltration, reverse osmosis and membrane coupled photocatalytic process        . "
ABSTRACT: This study reports a possibility of the household greywater treatment by solar photocatalysis followed by flocculation with special emphasis on hair colorants and accompanying chemicals. The greywater of concern (hereafter: GW) was collected from the bathroom after hair dyeing, washing and rinsing. Its tentative composition was determined taking into account listed ingredients of used hair colorant, dyeing chemistry and measured values of surface tension, light absorption and scattering. In order to assess the quality of the effluent, TOC, COD, BOD 5 and toxicity toward yeast and Vibrio fischeri were determined. Greywater was treated in the hand-made reactor system, with a constant recirculation over photocatalytic layer exposed to direct sunlight. Photocatalytic layer consisted of TiO 2 -coated textile fibers prepared by applying TiO 2 –chitosan pasteous dispersion on polyester/wool blend textile (75% polyester, 25% wool). Results showed the significant decrease in organic content, COD and toxicity over a period of 4 h. UV–vis spectra of treated samples indicate the complete degradation of dye molecules and certain aromatic compounds. Emulsifying compounds and surfactant concentrations were reduced significantly. Preliminary kinetic study involving chitosan dissolution kinetics and pollutant mineralization was pre-sented. It was observed that chitosan dissolved at certain extent during photocatalytic treatment, thus acted as an efficient flocculant in treated wastewater; flocs were observed shortly after photocatalytic treatment, followed by complete sedimentation over a period of 12 h in dark. Additionally, surface of the photocatalytic layer was analyzed by TGA, FTIR, ESR and Raman spectroscopy, SEM and contact angle measurements. Evidence of Ti (III) species was presented.04/2015; 5:15-27. DOI:10.1016/j.jwpe.2014.12.008
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- "In comparison with physical   and chemical treatments   , the SMBR technology was addressed as the only technology able to achieve satisfactory removal efficiencies of organic substances, surfactants and microbial contaminations without a post-filtration and disinfection step . In other words, the SMBR technology has proved to be the most efficient method for grey water treatment and reuse since it combines physical separation of colloidal substances, including pathogenic bacteria, together with aerobic biological treatment of dissolved organic matter . However, the treatment of wastewater by SMBR system is still suffering from the membrane fouling phenomena which is currently considered the main obstruct in SMBR applications . "
ABSTRACT: he performance of a submerged membrane bioreactor (SMBR) system for grey water (GW) treatment was evaluated in terms of effluent quality and membrane fouling. The SMBR was operated for 42 days at constant transmembrane pressure (13 kPa) in six consecutive stages. A hollow fibre ultrafiltration membrane module (ZW-1) was used to treat real GW with the aim of producing effluent that meets reuse guidelines for non-potable standards. A complete retention for activated sludge was maintained in the bioreactor to minimize the amount of sludge disposed into the environment. The results demonstrated that the SMBR system was able to reduce effectively the COD, NH3–N, turbidity, and colour to have values of 45 mg/L, 0.26 mg/L, 3 FTU and 18 PtCo in the effluent, respectively. Furthermore, a complete removal of total suspended solids (TSS) was achieved and faecal coliform concentration was below the determination threshold. In terms of membrane permeability, the results showed that the cake layer contributed significantly (86%) in reducing the permeation flux. The time-dependent permeation flux was modelled adequately according to an exponential expression. Ultimately, the treated GW by SMBR system can be considered as a good source for the most stringent non-potable reuse standards in arid areas.Journal of Membrane Science 02/2015; 476:40–49. · 4.91 Impact Factor