Kinetic Behaviour of the Activated Sludge Process Used for Treating Composite Chrome Tannery Wastewater
Supriyo Goswami, Debabrata Mazumder
More details
Hide details
Civil Engineering Department, Indian Institute of Engineering Science and Technology,
Shibpur P.O.– Botanic Garden, Howrah – 711 103, India
Submission date: 2015-06-08
Final revision date: 2015-08-24
Acceptance date: 2015-08-25
Publication date: 2015-11-27
Pol. J. Environ. Stud. 2015;24(6):2405–2409
Chrome tannery wastewater poses a serious environmental threat due to its high chemical oxygen demand (COD), bio-chemical oxygen demand (BOD5), nitrogen, total suspended solids (TSS), chromium, sulphide, chloride, etc. As a result, the composite chrome tannery wastewater is not treated satisfactorily in most cases owing to various toxic/inhibitory substances. Out of various biological methods available for the treatment of composite chrome tannery wastewater, the activated sludge process (ASP) is a proven technology. The process design of the ASP reactor with rational approach always warrants authentic values of kinetic coefficients regarding substrate removal and biomass growth. Therefore, the kinetic behaviour of substrate (i.e. COD) removal and biomass growth must be established prior to use of any model. Apart from this, the biodegradation potential of the concerned wastewater needs to be adjudged to take appropriate measures during treatment. The present study was performed to examine the treatability of the composite chrome tannery wastewater using an acclimated suspended biomass under batch mode of operation. The study also aims to determine the kinetic co-efficient for biodegradation based on the most favourable kinetic model. A laboratory- scale ASP reactor was run for conducting the batch study on COD removal from composite tannery wastewater and also for determining the kinetic coefficients. The results of several batch experiments revealed the efficacy of the ASP system in treating composite chrome tannery wastewater, but some inhibition was also noticed. Consequently, the Haldane growth kinetic model was found best fitting for biodegradation of chrome tannery wastewater using mixed microorganisms. The batch study was carried out under varying batch periods to determine five kinetics constants, viz. Ks, k, ki, Y, and kd from the experimental data. The values of all the kinetic coefficients are tallying with past kinetic studies on composite tannery wastewater.