MS Rahman and MA Islam 2014.

ORIGINAL ARTICLE A simple cost-effective manometric respirometer: design and application in wastewater biomonitoring Mohammad Shahidur Rahman • Md. Akhtarul Islam Recei ved: 31 July 2013 / Acce pted : 31 March 2014/ Publ ishe d online: 23 May 2014 The Author(s) 2014. This article is published with open access at Springerlink.com Abstract App lic atio n of res piro met ric tools in was tewate r engineering fields is still not getting familiarity and accep- tance by academy or industry in developing countries as compared to the use of conventional biochemical oxygen demand (BOD) approa ch. To jus tif y the app licabi lity of respirometry, a low-cost respirometric device suitable for monito ring biodegrada tion proce ss in waste water has been dev eloped. Thi s dev ice con tain s six indepe nde ntly ope rati ng reacto rs place d in a temperatur e contro l unit for the b ioassa y of five wastewater samples simultaneously (along with one blank ). Each react or is equipp ed with a magnetic stirrer for the continuous agitation of the test sample. Six manometers, linked with the ind ivid ual rea ctors, measure the pre ssure and volume changes in the headspace gas phase of the reactor. Working formulae have been derived to convert the ‘volume -ch ange in gasphase’data to ‘the oxy gen dep letion in the who le liquid–ga s sys tem’ dat a. The per for mance of the device has been tested with glucose–glutamic acid standard solution and found satisfactory. Conventional BOD test and the respiro metric measuremen ts were performed simulta - neousl y and it is found that in addi ti on to measu rin g the BOD of the sample, this device gives oxygen uptake profile for further analy sis to determine the biokinetic coeffi cients. Additionally, in some cases, following a specific test proto- col , the res pir omet er can indirec tly est ima te the car bon dioxide evolved during biodegradation process for calcu- lat ing res pira tor y act ivi ty par ame ter suc h as res pira tor y quotient. It is concluded that the device can be used in the laboratories associated with the activated sludge plants and also for teachin g and res ear ch pur pos es in developing countries. Keywords Headspace gas respirometer Wastewater Biokinetic coefficients Oxygen uptake rate BOD COD RQ Introduction The efficiency of an activated sludge plant depends on the abili ty of the bio ma ss to min eralize bi odegr adable org anics at a desire rate so as to meet effluent standards. The oxygen uptake, in this regard, reflects the ability of the biomass to metaboli ze wastewater components (Hill et al. 1998). Respi- rometry, which is widely used for the monitoring of oxygen uptake in different biochemical processes provides a proce- dure to as sess the state of mic robia l ac tiv ity and is use d for the determination of the parameters of microbial kinetic models including the characterization of wastewater and activated sludge (Marsili and Tabani 2002; Young and Cowan 2004). Respi rometr ic techni que was initia ted in study ing the biodegradability of wastewater as early as in 1920s. The instrument designed for the purpose is known as Barcroft- Warburg device. It represents a simple system consisting of a liquid reactor connected with a manometer (Jowett 1928; Perkins 1943). The biodegradation process takes place in the liquid phase of the reacto r wit h the consumpt ion of oxygen. The oxygen is transferred from the gas phase to the liquid, resulting in a loss of pressure in the gas phase. This pressure-loss is monitored by the manometer. M. S. Rahman (&) Department of Civil and Environmental Engineering, Shahjalal University of Science and Technology, Sylhet, Bangladesh e-mail: msr.ceesust@gmail.com URL: https://www.sust.edu M. A. Islam Department of Chemical Engineering and Polymer Science, Shahjalal University of Science and Technology, Sylhet, Bangladesh 1 3 Appl Water Sci (2015) 5:241–252 DOI 10.1007/s13201-014-0185-7

MS Rahman and MA Islam 2014.

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