The Role of Inorganic Metal Salts in Wastewater Clarification

An investigation into the ability of four inorganic coagulants namely; alum (Al2(SO4)3.18H2O), ammonium aluminum sulphate (NH4Al(SO4)2.12H2O), ferrous sulphate (FeSO4) and ammonium ferrous sulphate (NH4)2Fe(SO4)2.6H2O) in clarifying wastewater was examined. Results obtained from conventional standard ‘jar-test’ experiments indicated that alum was the most effective coagulant since it reduced turbidity of the wastewater to 0.64 NTU at a contact time of 300 min. Ferrous sulphate was the least effective coagulant, reducing turbidity of the wastewater to 3.45 NTU only at 240 min contact time, but when the contact time of the experiment was increased from 240 to 300 min, re-coloration of the solution was observed indicating re-stabilization of suspended particles. These findings tend to support the claim that alum is a choice coagulant for wastewater clarification.

The Role of Inorganic Metal Salts in Wastewater Clarification

An investigation into the ability of four inorganic coagulants namely; alum (Al2(SO4)3.18H2O), ammonium aluminum sulphate (NH4Al(SO4)2.12H2O), ferrous sulphate (FeSO4) and ammonium ferrous sulphate (NH4)2Fe(SO4)2.6H2O) in clarifying wastewater was examined. Results obtained from conventional standard ‘jar-test’ experiments indicated that alum was the most effective coagulant since it reduced turbidity of the wastewater to 0.64 NTU at a contact time of 300 min. Ferrous sulphate was the least effective coagulant, reducing turbidity of the wastewater to 3.45 NTU only at 240 min contact time, but when the contact time of the experiment was increased from 240 to 300 min, re-coloration of the solution was observed indicating re-stabilization of suspended particles. These findings tend to support the claim that alum is a choice coagulant for wastewater clarification.

The Role of Inorganic Metal Salts in Wastewater Clarification

An investigation into the ability of four inorganic coagulants namely; alum (Al2(SO4)3.18H2O), ammonium aluminum sulphate (NH4Al(SO4)2.12H2O), ferrous sulphate (FeSO4) and ammonium ferrous sulphate (NH4)2Fe(SO4)2.6H2O) in clarifying wastewater was examined. Results obtained from conventional standard ‘jar-test’ experiments indicated that alum was the most effective coagulant since it reduced turbidity of the wastewater to 0.64 NTU at a contact time of 300 min. Ferrous sulphate was the least effective coagulant, reducing turbidity of the wastewater to 3.45 NTU only at 240 min contact time, but when the contact time of the experiment was increased from 240 to 300 min, re-coloration of the solution was observed indicating re-stabilization of suspended particles. These findings tend to support the claim that alum is a choice coagulant for wastewater clarification.

The Role of Inorganic Metal Salts in Wastewater Clarification

An investigation into the ability of four inorganic coagulants namely; alum (Al2(SO4)3.18H2O), ammonium aluminum sulphate (NH4Al(SO4)2.12H2O), ferrous sulphate (FeSO4) and ammonium ferrous sulphate (NH4)2Fe(SO4)2.6H2O) in clarifying wastewater was examined. Results obtained from conventional standard ‘jar-test’ experiments indicated that alum was the most effective coagulant since it reduced turbidity of the wastewater to 0.64 NTU at a contact time of 300 min. Ferrous sulphate was the least effective coagulant, reducing turbidity of the wastewater to 3.45 NTU only at 240 min contact time, but when the contact time of the experiment was increased from 240 to 300 min, re-coloration of the solution was observed indicating re-stabilization of suspended particles. These findings tend to support the claim that alum is a choice coagulant for wastewater clarification.

I. The monoclinic double sulphates containing ammonium. Completion of the double sulphate series

In this communication are described the five remaining double sulphates of the series R 2 M(SO 4 ) 2 . 6H 2 O, in which R is ammonium and M is nickel, cobalt, manganese, copper, and cadmium. The ammonium salts, in which M is magnesium, zinc, and iron, have been described in two previous communications, in the latter of which (that concerning ammonium ferrous sulphate) a number of general questions concerning the whole series were also discussed. The present contribution completes the author’s work, commenced in the year 1890, on the double sulphates of this important monoclinic series, in all 31 salts, of which the It bases have been potassium rubidium, cæsium, ammonium, and thallium. Excluding thallium—of which only the zinc double sulphate has been included, the other double salts containing thallium not having yet been obtained in crystals of the perfection necessary for detailed accurate work of the character regarded as essential by the author—the four bases, potassium, rubidium, cæsium, and ammonium should give rise, with the eight several dyad bases above enumerated, to 32 double sulphates. All these have been obtained in excellent crystals, and fully described, with the two exceptions of potassium manganese and potassium cadmium sulphates, which, for some as yet undiscovered reason, are incapable of preparation. Yet so thoroughly are the relations between the various salts, and the rules governing the replacement of any one alkali base by any other, now understood, that it has been found possible to predict the constants of the two missing salts. Of the isomorphous double selenates, nine salts (including thallium zinc selenate) containing magnesium and zinc as M metals have already been described by the author, and it is intended that the remaining double selenates, those containing the other dyad metals, shall form the subject of the author’s next communication. Morphology . The first measurements of the crystals of this salt were made 60 years ago by Marignac, and the salt was included four years later by Murmann and Rotter in their comprehensive crystallographic investigation. The forms observed in both investigations were the same as those given in the list below, except a {100} and o {111}, and the values observed for the principal angles will be found quoted in the two last columns of the table of angles.

Ammonium ferrous sulphate and its alkali-metal isomorphs

Ammonium ferrous sulphate, (NH 4 ) 2 Fe(SO 4 ) 2 6H 2 O, although one of the commonest double salts in everyday laboratory use, and noted for its excellent, comapratively stable, clearly transparent, plae greenish-blue crystals, has never yet been subjected to a through crystallographic and optical study. Since the year 1859, when a few of its principal angles were measured by Murmann and Rottter, and an approximate idea of its optical properties for red, yellow, and green light of no specific wave-lengths briefly indicated, just adequately to confirm that the salt belongs to the monoclinic series of double sulphates crystallising with 6H 2 O, no accurate measurements have been made. The substance has, however, formes the subject of several special researches from a different point of view, such as those of von Hauer on the parallel growths of this salt on crystals of other salts of the series, of Baumhauer concerning the etch-figures produced on the various faces of the crystals by a small quantity of water, by St. Meyer on the nature of the crystals deposited under the influence of a magnetic field, by Wulff on the different rapidity of growth of the different crystal faces, and by von Fedorow concerning the correct setting of the crystals for descriptive purposes. But this salt was not included in the well-known series of optical investigations of Topsöe and Christiansen in 1874-5, nor the later one of Perrot, and has not been hitherto included by the author in his detailed investigation of the salt of this isomorphous series. This omission is now, however, removed by this communication.