SYSTEM AND METHOD FOR SEPARATING NUTRIENTS FROM A WASTE STREAM
A system and method to separate and concentrate nutrients from process waste water comprising the steps of accumulating the process waste water in a settling tank; settling the solids to form a supernatant and settled sludge; filtering the supernatant with a filtration system to form a permeate and a concentrate; dewatering the settled sludge to form thickened solids and a pressate; and, blending the thickened solids and the concentrate to form a slurry.
1 . A method to separate nutrients from a waste stream comprising the steps of:
a) accumulating said waste stream in a settling tank;
b) settling solids in said settling tank to form a supernatant and a settled sludge;
c) filtering the supernatant with a filtration system to form a first permeate and a first concentrate;
d) dewatering said settled sludge to form thickened solids and a pressate; and
e) blending said thickened solids and said concentrate to form a slurry.
2 . The method of claim 1 further comprising the step of delivering said slurry to an anaerobic digester.
3 . The method of claim 1 further comprising the step of adding a coagulant to said waste stream prior to said step of settling solids in said settling tank.
4 . The method of claim 1 wherein, the said step of dewatering said settled sludge further comprises gravity thickening of said settle sludge to form a sludge supernatant and a thickened sludge.
5 . The method of claim 4 , further comprising the step of accumulating said sludge supernatant in said settling tank.
6 . The method of claim 1 wherein, the step of dewatering said settled sludge comprises using apparatus selected from the group consisting of: a belt filter press, a centrifuge, a rotary press, a screw press, and a plate filter press.
7 . The method of claim 1 wherein the step of filtering said supernatant comprises filtering with a filtration system selected from the group consisting of micro-filtration, ultra-filtration, nano-filtration, and reverse osmosis.
8 . The method of claim 1 , wherein the step of filtering said supernatant with a filtration system comprises the steps of:
a) filtering said supernatant with an ultrafiltration system to form an ultrafiltration sludge and an ultrafiltration filtrate; and,
b) filtering said ultrafiltration filtrate with a reverse osmosis system to form said first permeate and said first concentrate.
9 . The method of claim 8 further comprising the step of dewatering said ultrafiltration sludge.
10 . The method of claim 8 wherein filtering said filtrate with a reverse osmosis system further comprises the steps of:
a) filtering said filtrate with a first reverse osmosis component to form said first permeate and a second concentrate;
b) filtering said second concentrate with a second reverse osmosis component to form said first concentrate and a second permeate.
11 . The method of claim 9 further comprising the step of accumulating said pressate in said settling tank.
12 . A method to separate nutrients from a waste stream comprising the steps of:
a) accumulating said waste stream in a settling tank;
b) settling solids in said settling tank to form a settled sludge and a supernatant;
c) filtering said supernatant with an ultrafiltration system to form an ultrafiltration sludge and a filtrate;
d) filtering said filtrate with a reverse osmosis system to form a first permeate and a first concentrate,
e) dewatering said settled sludge to form thickened solids and a pressate;
f) blending said thickened solids and the first concentrate to form a slurry.
13 . The method of claim 12 further comprising delivering said slurry to an anaerobic digester.
14 . The method of claim 12 further comprising adding a coagulant to said waste stream prior to the step of settling solids in said settling tank.
15 . The method of claim 12 further comprising the steps of:
a) dewatering said settled sludge by gravity thickening to form a sludge supernatant and a thickened sludge;
b) dewatering said thickened sludge to form said thickened solids and said pressate.
16 . The method of claim 15 further comprising the step of accumulating said sludge supernatant in said settling tank.
17 . The method of claim 12 further comprising the steps of:
a) accumulating said waste stream in an equalization tank before said step of accumulating said waste stream in a settling tank; and,
b) discharging said waste stream to said settling tank.
18 . The method of claim 17 further comprising the step of accumulating pressate in said equalization tank.
19 . The method of claim 12 wherein filtering said filtrate with a reverse osmosis system further comprises the steps of:
a) filtering said filtrate with a first reverse osmosis component to form said first permeate and a second concentrate;
b) filtering said second concentrate with a second reverse osmosis component to form said first concentrate and a second permeate.
20 . The method of claim 18 further comprising the step of filtering said second permeate with said ultrafiltration system.