Here are the answers to the May 20, 2021 edition of TPO's Exam Study Guide:
1. When selecting a polymer for dewatering on a belt-filter press, what performance requirement should be conducted before making a choice of polymers?
The answer to this question is C, jar test. Selecting the proper polymer for dewatering sludge is very important. Using polymers matched to your plant’s sludge characteristics can make a huge difference. Too much conditioning can be costly and leave needs unmet, while too little can result in ineffective dewatering and possible excess costs in handling and sludge application. Jar tests are effective means of testing different types or concentrations of polymers at the same time.
2. The backwash rate for a granular activated carbon filter should be sufficient enough to achieve a bed expansion of about ________ percent.
The correct answer is C, 50%. It is essential that proper backwashing procedures are followed to ensure adequate filtration and adsorption is performed. If the media is not properly cleaned, the effectiveness of both filtration and adsorption is lost, and mudballs may start to develop. Polymers being fed as filter aids may also contribute to the development of mudballs if the media is not expanded to about 50% during a backwash. It is also important to note the density of granular activated carbon is less than other filter media, so it can be easily washed out if the backwash rate is too excessive.
