Laundry greywater treatment using a fluidized bed reactor: a proposed model based on greywater biodegradation and residence time distribution approach

Abstract

The increasing demand for water and the decrease in global water resources require research into alternative solutions to preserve them. The present study deals with the optimization of a treatment process, i.e. an aerobic fluidized bed reactor and the modelling of the degradation that takes place within it. The methodology employed is based on the hydrodynamics of the treatment process linked to the biodegradation kinetics of greywater coming from a washing machine. The residence time distribution (RTD) approach is selected for the hydrodynamic study. Biodegradation kinetics are quantified by respirometry and dissolved organic carbon (DOC) analysis on several mass quantities of colonized particles. RTD determinations show that there are no dysfunctions in the fluidized bed. Its hydrodynamic behaviour is similar to the one of a continuous stirred-tank reactor. A first-order reaction is obtained from the DOC biodegradation study. A model describing the degradation that takes place into the reactor is proposed, and from a sensitive study, the influence of the operating conditions on DOC biodegradation is defined. The theoretical results calculated from the first-order equation C(t) = 0.593 x C(0) x e(-kt) are compared with the experimental results and validated by a Student test. The value of the kinetic constant k is 0.011 h(-1) in the presence of a biomass carrier. The results highlight that it is possible to design a reactor in order to obtain a carbon content lower than 15 mg C L(-1) when the characteristics of raw greywater are known.

Greywater reuse as a key enabler for improving urban wastewater management

“… 5-6 Low footprint, good biomass retention for increased organic removal, extra disinfection to avoid health risks, compliance with water standards An additional cost of chlorination apart from the challenges mentioned for membrane bioreactors [ 155 ] Integrated fixed-film activated sludge 0.03 - COD = 92.52%, LAS = 94.24%, Oil and grease = 90.07% - Higher resistance to organic and hydraulic loading than conventional activated sludge High construction and maintenance cost, expert knowledge required, high energy consumption due to aeration [ 157 ] Aerobic fluidized bed reactor 0.14 - COD = 73%, Anionic surfactant = 57%, TN = 42%, TSS = 66%, DOC = 52% - Excellent mixing and high mass transfer for good biodegradation, fluidized materials accommodate microbial growth Expert knowledge is required for maintenance and operation. [ 158 ] Moving bed biofilm reactor + UV disinfection 1 2.4 COD = 93%, BOD 5 = 97%, - Higher biomass concentration, higher organic removal, lower hydraulic residence times, sound mixing and mass transfer, and disinfection ensure microorganisms removal Manual monitoring is required. Insects are attracted to biofilm reactors.…”

Utilisation d’un lit fixe d’origine naturelle pour le traitement biologique d'effluents laitiers

“…Les anneaux Kaldnes connaissent particulièrement une grande utilisation. D'autres types de matériaux sont aussi employés tels que le verre, l'éponge ou aussi le métal (Kargi et Eyiisleyen, 1995 ;Arumugam et Sabarethinam, 2008 ;David et al, 2013). Les matériaux d'origine naturelle présentent certains avantages, notamment leur disponibilité à des coûts faibles.…”