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Water/Wastewater Math Operations
Published in Frank R. Spellman, Handbook of Water and Wastewater Treatment Plant Operations, 2020
In chemical dosing, a measured amount of chemical is added to the wastewater (or water). The amount of chemical required depends on the type of chemical used, the reason for dosing, and the flow rate being treated. The two expressions most often used to describe the amount of chemical added or required are: Milligrams per liter (mg/L)Pounds per day (lbs/day)
The pre-acidification gas impact on upgrading the biogas produced in expanded granular sludge bed reactor
Published in Biofuels, 2022
Haider Al-Rubaye, Joseph D. Smith, Manohar Shivashankaraiah, Jia Yu, Mahyar Ghorbanian, Anand Alembath, Hasan Al-Abedi
The pre-acidification tank is 125 L total volume (active volume is about 68 L) made of stainless-steel material and equipped with a stainless-steel mixer to maintain a uniform temperature and mass distributions. A Milwaukee pH controller instrument with (MP810) dosing pump was installed to pump sodium hydroxide (NaoH) to adjust the pH of the substrate. Nutrient supplements were also added into the PA tank to keep the microorganisms active. The PA reactor was insulated to avoid heat loss and was equipped with a submersible heater controlled by a temperature control to maintain the required temperature. To capture the PA gas that produced in the PA reactor, two vacuum pumps (Focal Flux, Max pressure delivery 35 psi) 12 V DC were connected in parallel and got energized by a timer switch that runs the pumps for 30 s every 90 min at a time. The PA gas that vacuumed from the PA reactor was stored in a 20 L steel tank rated up to 250 psig. The PA storage tank was connected to a pressure transducer (Omega pressure transducer model PX304 with transducer indicator DP-350). The PA gas then flows through a mass flow controller into the bottom of the EGSB reactor. Two BT300S basic variable speed peristaltic pumps have been used with pump heads (YZ15), the first one was used to pump the substrate (volatile fatty acids) from the PA reactor to the EGSB reactor and the second one was used to control the recycle stream of the effluent back into the system again at a certain ratio.
Unfolding ‘big’ problems of small water system performance: a qualitative study in British Columbia
Published in Canadian Water Resources Journal / Revue canadienne des ressources hydriques, 2020
Sarin Raj Pokhrel, Gyan Chhipi-Shrestha, Manuel J. Rodriguez, Kasun Hewage, Rehan Sadiq
In regards to maintaining residual chlorine levels, the findings revealed that 72% of respondents adjusted dosage with respect to varying chlorine concentration needs at different locations in the DN. Forty-three percent of respondents adjusted chlorine dosages according to the water quality changes at the upstream dosing point, and 17% adjusted the dose based on the change in temperature. Based on the questionnaire findings, 45% of respondents used the calorimetric method (diethyl paraphenylene diamine [DPD]) to test residual chlorine in DNs. Eighteen percent of respondents relied on both DPD and membrane-covered polarographic sensors, while 12% of respondents used DPD and potentiometry as primary methods to test residual chlorine. The results indicated that 38% of respondents used both manual methods and sensors to monitor residual chlorine, while 33% relied only on manual sampling. The fact that the majority of respondents used one or two methods to check residual chlorine concentration is a welcome result. Residual chlorine is a good sentinel to reduce the probability of microbiological contamination, and wise monitoring of residual chlorine is important from a human health perspective.
Performance optimization of dewatering of coal fine tailings using Box–Behnken design
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2018
Puja Hansdah, Shravan Kumar, N. R. Mandre
The Box–Behnken statistical experimental design method was found to be appropriate for modeling the effects of important variable parameters of the settling rate. The prediction of response function determined by regression analysis was in good agreement with the experiment results. Pulp density is the most effective parameter followed by flocculant dose and pH. However, pulp density and pH negatively affect the settling rate, and the flocculant dose increases the settling rate to increase in the dosing rate. The R2 values between the experimental and the predicted values of the settling rate were found to be 0.99 indicating a good agreement between them. The highest settling rate of 221 mm/min was obtained at a pH of 7.5 at a flocculant dosage of 14.58 gpt at 6% pulp density.