Optimization of hydraulic retention time HRT employing

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J Bio Env Sci 2016, Introduction This demands more research in this field to make. Water being a vital component for the survival of treatment processes efficient and economical Keeping. human beings and determines the development of above in consideration this research aims to obtain. societies The availability of freshwater resources and the following objectives a Installation of automated. its distribution varies around the globe World Bank lab scale SBR setup b Temporal characterization of. 2005 The water usage in sanitation drinking NUST wastewater c Optimization of HRT using. manufacturing industries washing and agriculture is statistical analysis d Comparison of SBR. polluting water resources to a great extent It has been performance with synthetic and real wastewater. estimated that to meet the rising demand for There are few studies available on lab scale set up. horticulture many cities will face issues to access fresh before moving to full scale plant In order to save. water within the next 15 to 25 years Hastuti et al money time and effort this lab scale SBR was used to. 2011 Due to the increasing demand of water usage comprehensively analyzed and observe the treatment. Pakistan is shifting from water stressed country to a process before moving to pilot scale or full scale SBR. water scarce one In Pakistan 23 population lack at NUST campus. access to fresh and safe water for drinking and 30. population lack access to sanitation World Bank Materials and methodology. Report 2006 Experimental setup, Two bench scale sequencing batch reactors were setup. The prevailing situation in country demands the at IESE wastewater laboratory The volume of each. conservation of water resources and requires the reactor was six liters Four liters of wastewater was. treatment of wastewater so that it can be utilized for. treated in each cycle and one third of the reactor. irrigation landscaping and ground water recharge, volume that is two liters was having sludge The mixed. purposes Conventional wastewater treatment, processes are not effective in meeting the effluent liquor suspended solids MLSS was kept in range of 3. discharge standards especially in the removal of 5 mg l and sludge retention time SRT was 15 days. pathogens The impacts of discharging untreated and daily sludge discharge rate was 400ml Aerators. wastewater into the environment have significant having same capacity were provided to each reactor. health and ecological impacts specially on biodiversity One Feed tank was installed on upper head to provide. Asadi and Ziantizadeh 2011 Mamert et al 2016, same quality influent for both reactors under gravity.
The physico chemical Wastewater treatment are costly. flow Each reactor was provided with three timers to. and raises issues of sludge disposal which urges us for. cost effective treatment processes such as biological control inlet aeration and effluent in a sequence. treatment systems for removing pollutants and also These reactors were categorized based on the hydraulic. does not leave chemical sludge Kapdan and Oztekin retention time HRT The filling and decant time was. 2006 Matsumoto et al 2012 Lim and Vadivelu set at30 minutes and settling for 1 hour. 2014 Biological treatment has capacity to remove the. concentration of organic and inorganic compounds, The study was conducted in two phases In first phase. and also to transform nutrients Nawaz and Jamal, the reactors were operated on synthetic wastewater on. Khan 2013 Sequencing Batch Reactors SBR is,the hydraulic retention time HRT of 1 2 3 and 4. sequential suspended growth activated sludge,hours For all the HRTs sludge and wastewater. process where all steps are carried out in a single tank. parameters were analyzed and statistical analysis was. Lamine et al 2007 Xu et al 2014 SBRs are used, all over the world to treat both industrial and conducted HRT of 2 hours were statistically optimized.
municipal wastewaters predominantly in sectors and HRT of 2 and 3 hrs were shifted to real wastewater. having low and changing flow patterns Chan et al for further analysis. 2009 Calder n et al 2013 Chen et al 2015,130 Hasnain et al. J Bio Env Sci 2016, Fig 1 Schematic Diagram of Lab Scale Sequencing Batch Reactor. Phase I For real wastewater on optimized HRTs of 2hr and. In first phase synthetic wastewater was used for the 3hr the wastewater parameters comprised Chemical. acclimatization of sludge analysis of parameters on Oxygen Demand COD Nitrates Nitrites. different HRTs and statistical analysis Synthetic waste. Ammonium N NH4 N Phosphates Total Ortho,water with a medium strength having C N P as. and Total Suspended Solids TSS while sludge,100 10 2 was used as substrate. parameters analyzed Mixed Liquor Suspended Solids,Analytical Methods.
MLSS Sludge Volume Index SVI Extra Polymeric,Chemical Oxygen Demand COD Orthophosphates p. Substances EPS Capillary Suction Time CST using,and Total Suspended Solids TSS were analyzed. TYPE 304B CAPILLARY SUCTION TIMER and,wastewater parameters while sludge parameters. include Sludge Volume Index SVI MLSS and CST Particle Size Analysis PSA was measeured using. All these parameters were analyzed as per Standard HORIBA Laser Scattering Particle Size Distributon. Methods for the Examination of Water Wastewater Analyzer. 22st Edition 2012 APHA 2012 COD was measured, using COD reactor Nutrients and Phosphates using EPS determines the extracellular polymeric substances. Hach meter SVI was done to monitor the settling, in form of soluble loosely and tightly bound present in.
characteristics of sludge using Imhoff cones and MLSS. the sludge All these are further catagorized in,using Whatzman filter paper 47mm filter assembly. polysaccharides and proteins The more the tightly,bound substances present the more become its. Real Wastewater Collection, particle size Because of this its dewatering capacity is. Real wastewater of NUST was collected from NUST, enhanced and its capillary suction time CST reduces. main drain The sample was collected using global,Statistical analysis was done for all analyzed.
water sampler mostly in the morning around 08 00,parameters on both 2hr and 3hr HRTs for the. 09 00 am and 02 00 03 00 pm when there was a high, load of COD and nutrients in wastewater optimization. Analytical Methods Statistical Analysis,131 Hasnain et al. J Bio Env Sci 2016, In statistical analysis two tools were used the first is. the analysis of variance ANOVA and the second one, is two tail t test ANOVA determines the statistically.
significant distinction among more than two scenarios. while Post hoc Test Two Tail t Test shows the, statistically significant distinction between a pair of. scenarios Both of these tests were based on a, hypothetis which is called null hypothesis Our null. hypothesis for both tools was as follows,For ANOVA Ho 1 2 3 i Ha At least one of. mean reduction is distinct,i mean reduction of COD of ith hour sample. For Two Tail t Test Ho 1 2 Ha 1 2 To,approve this hypothesis.
P value Probability usually a confidence level of 2. 5 and 10 is used whereas we accepted confidence of. 5 which is also called probability of null which Fig 2 a MLSS concentration of 1hr and 2hr HRT b. determines whether there is a fair chance to accept the MLSS concentration of 3hr and 4hr HRT. hypothesis or not So if p value is less than 5 null. hypothesis can be rejected because there is a less. probability that our hypothesis is accepted which was. that for both the scenarios the percentage mean,reduction was same So we can reject the null and. conclude that both percentage reductions are, statistically significantly different on the average In. case if p value is greater or equal than 5 null, hypothesis cannot be rejected which means that both. the reactors is statistically significantly same,Results and discussion. Phase I Synthetic Wastewater,Effect of Hydraulic Retention Time HRT on MLSS.
MLSS concentration remained between 3 6 g L for, both 1 hr and 2 hr HRTs On average MLSS of 2hr HRT Fig 3 a MLSS concentration of 3hr and 4hr HRT. was 4 53g L slightly higher than the MLSS of 1hr HRT b MLSS concentration of 3hr and 4hr HRT. which was 4 48g L Fig 2 a The reason is 1hr HRT, was not enough for microbes to utilize the food Referring to fig 3 comparison was made between 3hr. properly that s why its SVI exceeded 150 mL g which and 4 hr HRT The MLSS concentration of 3hr HRT. showed its poor settling characteristics Problem of was higher than 4hr HRT as the average MLSS. sludge bulking were also experienced for 1hr HRT concentration for 3hr HRT was 4 94g L and for 4hr. While for 2hr HRT sludge was dense and showed good HRT it was 3 95g L The sludge of 3hr HRT had better. settling characteristics as its average SVI was 83 90 settling than 4hr HRT as its average SVI value was. mL g shown in fig 2 b 103 66mL g The average SVI for 4hr HRT was. 130 47mL g,132 Hasnain et al,J Bio Env Sci 2016, COD Removal Efficiency for different HRTs Orthophosphates Removal Efficiency on Different. For 1hr HRT due to its poor settling characteristics HRTs. and sludge bulking issues its COD removal was Orthophosphate removal efficiency was almost same. insufficient so we did not mention its data here For all for 2hr 3hr and 4hr HRTs as shown in fig 5 a b c. others COD removal efficiency kept on increasing as. the sludge got acclimatized For 2hr HRT average,COD removal was recorded as 84 89g L for 3hr HRT. it was 85 63g L and was 87 11g L for 4hr HRT The, COD concentrations at influent and effluent along with.
their efficiencies for 2hr 3hr and 4hr HRTs are shown. in fig 4 a b c From there graphs it can be observed. that there is a slight difference between the COD, removal efficiency of 3hr and 4hr HRT So it is suitable. to work at 3hr to be cost and energy efficient as 1 extra. hour results in only 2 increase in COD removal,efficiency. Fig 5 a Orthophosphate P removal efficiency for,2hr HRT b Orthophosphate P removal efficiency for. 3 hr HRT c Orthophosphate P removal efficiency for. It can be observed from above graphs that on average. phosphate removal efficiency of 2hr HRT was recorded. as 75 56 which was better than 69 41 and 71 19, for 3hr and 4hr respectively This is due to its high. MLSS concentration There is more phosphate, Fig 4 a COD removal efficiency for 2hr HRT b accumulating organisms PAOs present in 2hr HRT.
COD removal efficiency for 3hr HRT c COD removal due to more presence of mixed liquor suspended. efficiency for 4hr HRT solids,133 Hasnain et al,J Bio Env Sci 2016. Phase II Real Wastewater Because of the real wastewater there was a lot of. The Effect of HRT on MLSS and SVI fluctuation in inlet filtered COD concentrations. Fig 6 a illustrates the MLSS variations in both SBR ranging from 80 230 mg L. reactors i e HRT 2hr HRT 3hr As we can observe, from graph that both reactors have a lot of variation in. MLSS concentration due to the diurnal COD, concentration in influent Also we can observe that. MLSS concentration of HRT 2 is greater than HRT, 3 The average concentration of MLSS of HRT 2hr and. HRT 3hr is 3 4 g L and 2 8 g L respectively The, reason behind increased MLSS of HRT 2hr is that the.
reactor with HRT 2 is completing more cycles than, HRT 3 per day and hence getting more food in term of. influent COD As MLSS and SVI has indirect relation Fig 7 COD concentration at influent and effluents. so for 2hr HRT SVI is 46 32 mL g on average and the. sludge is dense and has good settling characteristics Fig 8a b are the combination graphs which show the. influent effluent concentration along with removal. While for 3hr HRT the SVI is 60 56 on average which. efficiencies for both 2hr and 3hr HRT respectively As. is greater than of 2hr as its MLSS is less but the sludge. shown in both graphs the fluctuation in COD at,is in a good settling range as shown in fig 6b. influent was observed which resulted in the variations. in COD removal efficiency as MLSS did not increase. with a same rate as in the synthetic wastewater On. average 2hr HRT showed a high COD removal, efficiency than 3hr because of its higher MLSS The. more the MLSS the more the microbes present to,remove COD and higher becomes the COD removal. efficiency,Fig 8c shows the per hour comparison between COD.
removal efficiency of 2hr with 3hr HRT It can be easily. observed from graph that removal efficiencies of 2hr. HRT in both first and second hour is greater than 3hr. HRT due to the increased MLSS in 2hr HRT reactor as. discussed earlier Also the removal efficiency of 2hr. HRT increased more rapidly 53 74 than 3hr HRT,Fig 6 a MLSS concentration of 2hr and 3hr HRT. The Effect of HRT on Ammonia Removal,b SVI concentration of 3hr and 4hr HRT. Fig 9a b are the combination graphs of ammonia, The Effect of HRT on COD Removal nitrogen removal of reactors with HRT 2hr and HRT. The COD removal is the most important parameter for 3hr respectively The ammonia removal efficiency kept. assessing the performance of SBR Fig 7 shows the on decreasing for both reactors This might be due to. COD removal patterns of both SBR reactors at two the hindrance in the conversion of ammonia into. different HRTs i e at HRT 2hr and HRT 3hr for nitrites as we converted our setup from synthetic to. real wastewater real wastewater The reduction was almost same for. Schematic Diagram of Lab Scale Sequencing Batch Reactor Phase I In first phase synthetic wastewater was used for the acclimatization of sludge analysis of parameters on different HRTs and statistical analysis Synthetic waste water with a medium strength having C N P as 100 10 2 was used as substrate Analytical Methods Chemical Oxygen Demand COD Orthophosphates p and Total Suspended

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