Membrane processes for metal recovery and pollution control in metal process industries

A closed process for the treatment of an aqueous effluent stream produced in the manufacture of lead storage batteries which effluent stream contains a precipitatable material and at least one of an acid and a base, said process, in which all streams produced therein are recycled, comprising:

• (a) treating the effluent stream to selectively precipitate and remove the precipitatable material without precipitating significant quantities of the acid or base, thereby producing an aqueous stream;
• (b) treating the aqueous stream with reverse osmosis, thereby producing a relatively pure water stream and a concentrate stream;
• (c) treating the concentrate stream by water splitting, thereby producing acid, base, and deionate streams;
• (d) recycling the deionate stream directly to the reverse osmosis step (b);
• and
• (e) selectively recycling the water, acid, and base streams to at least one of said closed aqueous effluent stream treatment process and the process from which the effluent evolved,
• whereby most of the precipitatable material is extracted from the effluent in a relatively concentrated solid form.

A closed process for treating an aqueous effluent stream which contains a precipitatable material and at least one of an acid and a base, said process, in which all streams produced therein are recycled, comprising:

• (a) precipitating with a precipitating base the precipitatable material in such quantities that a significant amount of the acid is not precipitated;
• (b) removing the precipitated, precipitatable material, thereby producing an aqueous stream;
• (c) treating the aqueous stream by reverse osmosis, thereby producing a relatively pure water stream and a concentrated aqueous stream;
• (d) recycling the relatively pure water stream into the process from which the effluent evolved;
• (e) treating the concentrated aqueous stream by water splitting wherein a neutral salt is added to the base stream produced therein, thereby producing acid, base, and deionate streams, said base stream containing the precipitating base of step (a) and the neutral salt;
• (f) recycling the acid stream to the process from which the effluent stream evolved;
• (g) separating the precipitating base from the base stream, thereby producing a base stream containing the neutral salt;
• (h) recycling the base stream to the water splitting step (e);
• (i) recycling the precipitating base to the precipitating step (a);
• and
• (j) recycling the deionate stream directly to the reverse osmosis step (c),
• whereby most of the precipitatable material is extracted from the effluent in a relatively concentrated solid form.

A closed process for treating spent pickling streams and rinse water streams from iron pickling wherein said spent pickling streams comprise FeCl.sub.2, HCl, and NaCl, and the rinse water stream comprises FeCl.sub.2 and HCl, said process, in which all streams produced therein are recycled, comprising:

• (a) treating the spent pickling stream with water splitting, thereby producing acid, base, and deionate streams, wherein the base stream comprises NaOH, NaCl, and precipitated Fe(OH).sub.2 ;
• (b) concentrating the acid stream by electrodialysis, thereby producing a concentrated acid stream and an electrodialysis deionate stream;
• (c) recycling the concentrated acid stream to the iron pickling process;
• (d) filtering the Fe(OH).sub.2 from the base stream;
• (e) recycling part of the filtered base stream to the water splitting step (a);
• (f) neutralizing the rinse water stream with part of the filtered base stream, thereby precipitating Fe(OH).sub.2 ;
• (g) recycling the electrodialysis deionate and the deionate streams to the neutralization step (f);
• (h) filtering the Fe(OH).sub.2, thereby producing an aqueous stream;
• (i) treating the aqueous stream with reverse osmosis, thereby producing a relatively pure water stream and a concentrate stream;
• (j) recycling the relatively pure water stream to the iron pickling process;
• and
• (k) treating the concentrate stream in the water splitting step (a).

A closed process for treating a filtered effluent stream from nickel-cadmium battery manufacture, in which all streams produced therein are recycled, wherein the effluent contains NaOH, comprising:

• (a) neutralizing the effluent stream with the acid stream described in step (d) below, thereby producing a neutralized stream;
• (b) treating the neutralized stream with reverse osmosis, thereby producing a relatively pure water stream and a concentrate stream;
• (c) recycling the pure water stream to the battery manufacture process;
• (d) treating the concentrate stream with water splitting, thereby producing acid, base, and deionate streams;
• (e) recycling the acid stream to the neutralization step (a);
• (f) recycling the base stream which comprises NaOH to the battery manufacture process;
• and
• (g) recycling the deionate stream directly to the reverse osmosis step (b).

A closed process for the treatment of an aqueous effluent stream produced in a metal-treating process which effluent stream contains at least one of an acid and a base, said process, in which all streams produced therein are recycled, comprising:

• (a) treating the effluent stream by reverse osmosis, thereby producing a relatively pure water stream and a concentrate stream;
• (b) treating the concentrate stream by water splitting, thereby producing acid, base, and deionate streams;
• (c) recycling at least a portion of the pure water stream and the acid stream to the process from which the effluent stream evolved;
• (d) recycling the base stream to at least one of the processes from which the effluent stream evolved, and the water splitting step (b);
• and
• (e) recycling the deionate stream directly to the reverse osmosis step (a).

A closed process for the treatment of an aqueous effluent stream produced in a metal treating process which effluent stream contains a precipitatable material and at least one of an acid and a base, said process, in which all streams produced therein are recycled, comprising:

• (a) treating the effluent stream to selectively precipitate and remove the precipitatable material without precipitating significant quantities of the acid or base, thereby producing an aqueous stream;
• (b) treating the aqueous stream with reverse osmosis, thereby producing a relatively pure water stream and a concentrate stream;
• (c) treating the concentrate stream by water splitting thereby producing acid, base, and deionate streams;
• (d) recycling the deionate stream directly to the reverse osmosis step (b);
• and
• (e) selectively recycling the water, acid, and base streams to at least one of said closed aqueous effluent stream treatment process and the process from which the effluent evolved,
• whereby most of the precipitatable material is extracted from the effluent in a relatively concentrated solid form.

A closed process for the treatment of an aqueous effluent stream which effluent stream contains at least one of an acid and a base, said process, in which all streams produced therein are recycled, comprising:

• (a) treating the effluent stream by reverse osmosis, thereby producing a relatively pure water stream and a concentrate stream;
• (b) treating the concentrate stream by water splitting, thereby producing acid, base, and deionate streams;
• (c) recycling at least a portion of the pure water stream and the acid stream to the process from which the effluent stream evolved;
• (d) recycling the base stream to at least one of the processes from which the effluent stream evolved, and the water splitting step (b);
• and
• (e) recycling the deionate stream directly to the reverse osmosis step (a).

A closed process for the treatment of an aqueous effluent stream which effluent stream contains a precipitatable material and at least one of an acid and a base, said process, in which all streams produced therein are recycled, comprising:

• (a) treating the effluent stream to selectively precipitate and remove the precipitatable material without precipitating significant quantities of the acid or base, thereby producing an aqueous stream;
• (b) treating the aqueous stream with reverse osmosis, thereby producing a relatively pure water stream and a concentrate stream;
• (c) treating the concentrate stream by water splitting, thereby producing acid, base, and deionate streams;
• (d) recycling the deionate stream directly to the reverse osmosis step (b);
• and
• (e) selectively recycling the water, acid, and base streams to at least one of said closed aqueous effluent stream treatment process and the process from which the effluent evolved,
• whereby most of the precipitatable material is extracted from the effluent in a relatively concentrated solid form.