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Dissolved Matter
Published in Paul N. Cheremisinoff, Handbook of Water and Wastewater Treatment Technology, 2019
With proper treatment, the silica content of water may be reduced to unobjectionable amounts. If the water to be treated is a surface water which requires coagulation, the use of ferric sulfate as a coagulant will assist in reducing the silica content. Dolomitic lime or activated magnesia, especially in the hot lime soda process, is effective in treatment. The same materials are also used in the cold lime soda process. In ion-exchange demineralizing processes, silica may be removed by direct anion exchange in a strongly basic anion exchanger which has been regenerated by caustic soda (NaOH).
Recycling of Energy Storage Wastes
Published in Hong Hocheng, Mital Chakankar, Umesh Jadhav, Biohydrometallurgical Recycling of Metals from Industrial Wastes, 2017
Hong Hocheng, Mital Chakankar, Umesh Jadhav
Furthermore, a comparison of these bioleaching results with the previously reported chemical leaching using nitric acid (Sathaiyan et al. 2006, Aktas 2010) suggested that silver leaching using biologically produced ferric ions was as efficient as nitric acid leaching. About 98% silver was dissolved in 60 min. Therefore, the use of biologically produced ferric sulfate is advantageous over chemical leaching due to its efficiency and minimal impact on the environment.
Advancements in laundry wastewater treatment for reuse: a review
Published in Journal of Environmental Science and Health, Part A, 2022
Sushil Kumar, Ali Khosravanipour Mostafazadeh, Lalit R. Kumar, R. D. Tyagi, Patrick Drogui, Emmanuel Brien
Since many decades, chemical coagulation has been utilized for wastewater treatment. The inorganic coagulants like aluminum sulfate or iron salts (ferric sulfate, ferrous sulfate or ferric chloride) were the first ones to be used for the treatment. However, FeCl3 is corrosive and FeSO4 works only in the pH range of 8.5-11. Therefore, preference was given to aluminum sulfate and ferric sulfate which can be utilized in a varying pH range of 5-9 and 4-11, respectively.[20] Hazardous by-products like metal hydroxides are produced with the usage of above coagulants, which creates an additional problem of removing these metal ions from the treated water. Therefore, chemical coagulation process must be combined with adsorption. A high efficacy has been found with ligand based composite adsorbents that are selective for removal of metal ions from the LWW.[66] Natural and synthetic organic coagulants are supposed to give high efficacy with lower doses and hence, they tend to produce less volumes of sludge. They provide higher removal of turbidity and COD than the inorganic coagulants.[67] However, best results were obtained when low molecular weight polymers were added as coagulants during LWW treatment.[26]
Empirical evaluation of proposed treatment unit for saline wastewater softening
Published in Journal of Applied Water Engineering and Research, 2021
Mahmoud Taherizadeh, Farshad Farahbod, Alireza Ilkhani
It is worth mentioning that the removal of the total hardness of the wastewater is a function of several factors like the mixing speed in the reactor, amount of the sodium carbonate, sodium hydroxide amount as well as the amount of coagulant added to the process. In this study, three coagulants, namely ferric sulfate, ferric chloride and aluminum sulfate have been used for coagulation. Thus, the experiments have been undertaken with the objective of finding the optimal amounts of the above factors. At first, the temperature, acidity, total dissolved hardness, total hardness and alkalinity of a four liters’ sample of wastewater flowing out of the gravitational filtration unit was subjected to the measurements and then allowed to be poured into the first pretreatment reactor. In this state, the temperature and acidity measurements were commenced for the coagulant of choice, as well, and an amount of the selected coagulant matter was injected into the wastewater discharged into the first refinement reactor and the acidity and temperature were again measured. Afterwards, hydrated lime and sodium carbonate were added to the wastewater and the wastewater was stirred for two minutes in various velocities of 70, 90, 110 and 120 rpm (it is worth mentioning that the concentration of each of the prepared solutions injected to the wastewater was 10 g/l and it was in this stage that the coagulants’ structure was broken and Mg2+ and Ca2+ ions gave rise to the creation of a new complex with the coagulant). The schematic view in Figure 3(c) gives a better image of what has occurred in the softening and biological treatment units.