大量微(wei)氣泡的穩定(ding)形成是氣浮機(ji)凈(jing)水技術的關(guan)鍵所(suo)在,其特性對氣浮機(ji)凈(jing)水效果有重要影(ying)響(xiang)。
1。微氣(qi)泡大小
以往,人(ren)們都認(ren)為微(wei)氣(qi)(qi)泡越小則氣(qi)(qi)浮機(ji)效果越好。但近(jin)來的研(yan)究表(biao)明,這種看法存(cun)在一定的片面性,即微(wei)氣(qi)(qi)泡并不是越小越好,其(qi)原因主要有:
(1)微氣泡(pao)越小則絮體(ti)顆(ke)粒上浮所(suo)需粘附(fu)的微氣泡(pao)個數就(jiu)越多,顯然粘附(fu)更多的微氣泡(pao)比(bi)較(jiao)困難;
(2)微氣泡(pao)在產生過(guo)(guo)程(cheng)中需要克(ke)服其(qi)表面水分子層(ceng)的(de)表面張力而做功(即增加體(ti)系(xi)表面自由能(neng)),這是一個能(neng)量(liang)消耗(hao)過(guo)(guo)程(cheng)。顯然,微氣泡(pao)越(yue)小則能(neng)耗(hao)就越(yue)大;
(3)微氣(qi)(qi)泡越(yue)小則所受(shou)浮力就越(yue)小,越(yue)容易因水流攜(xie)帶作用而通過底(di)部集水系統(tong)進入后(hou)續濾池(造成氣(qi)(qi)阻(zu)等);
(4)微氣(qi)泡(pao)大(da)小(xiao)還受分(fen)離區表(biao)(biao)面(mian)負(fu)(fu)荷制(zhi)約。當氣(qi)浮機表(biao)(biao)面(mian)負(fu)(fu)荷增(zeng)(zeng)大(da)時,泡(pao)絮結(jie)合體(ti)在水中的(de)(de)(de)停留時間縮短,這時只有(you)增(zeng)(zeng)大(da)其上(shang)浮速率才能浮至水面(mian)。顯然,粘附一(yi)定數(shu)量(liang)的(de)(de)(de)小(xiao)氣(qi)泡(pao)比粘附同樣數(shu)量(liang)的(de)(de)(de)較(jiao)大(da)氣(qi)泡(pao)具有(you)更大(da)的(de)(de)(de)表(biao)(biao)觀(guan)相(xiang)對密度和更小(xiao)的(de)(de)(de)上(shang)浮速率,因此(ci)不利于(yu)增(zeng)(zeng)大(da)氣(qi)浮機表(biao)(biao)面(mian)負(fu)(fu)荷。基(ji)于(yu)以上(shang)原因,氣(qi)浮工(gong)藝(yi)中的(de)(de)(de)微氣(qi)泡(pao)大(da)小(xiao)應適當,過大(da)或過小(xiao)都會影(ying)響(xiang)氣(qi)浮
效果。生產(chan)實(shi)踐表明(ming),當表面(mian)負荷(he)約10m2/(m·h)時,控制微氣(qi)泡直徑在10-100mm范(fan)圍內(平(ping)均為40mm左右(you)),就能夠(gou)取得滿意的凈水效果。根據研究結果,當氣(qi)浮機表面(mian)負荷(he)增加到25m2/(m·h)或更大時,微氣(qi)泡的平(ping)均直徑在100mm左右(you)更合適。
2。微氣泡(pao)表面特性
一(yi)般(ban)來說,水(shui)中(zhong)微(wei)氣(qi)(qi)泡(pao)(pao)優先吸附(fu)(fu)(fu)某些負(fu)(fu)(fu)離(li)(li)子(zi)(zi)(zi)(zi)而帶負(fu)(fu)(fu)電(dian)(dian)(dian),相(xiang)應(ying)其(qi)表(biao)(biao)面(mian)(mian)(mian)電(dian)(dian)(dian)位為較(jiao)高負(fu)(fu)(fu)值(zhi)(zhi)。測量(liang)結(jie)果表(biao)(biao)明(ming),氣(qi)(qi)浮機中(zhong)微(wei)氣(qi)(qi)泡(pao)(pao)表(biao)(biao)面(mian)(mian)(mian)電(dian)(dian)(dian)位一(yi)般(ban)在-100mV左右,而絮(xu)體顆粒表(biao)(biao)面(mian)(mian)(mian)電(dian)(dian)(dian)位通常也(ye)為負(fu)(fu)(fu)值(zhi)(zhi),因(yin)此它(ta)們在相(xiang)互靠近時會(hui)存在靜電(dian)(dian)(dian)排斥作(zuo)用而對其(qi)碰(peng)撞粘附(fu)(fu)(fu)過(guo)程產生負(fu)(fu)(fu)面(mian)(mian)(mian)影響。原水(shui)水(shui)質及(ji)吸附(fu)(fu)(fu)的離(li)(li)子(zi)(zi)(zi)(zi)種類(lei)、數量(liang)不(bu)同則(ze)微(wei)氣(qi)(qi)泡(pao)(pao)強(qiang)度、表(biao)(biao)面(mian)(mian)(mian)憎水(shui)性(xing)能(neng)及(ji)電(dian)(dian)(dian)性(xing)等也(ye)有(you)所不(bu)同。向水(shui)中(zhong)添加電(dian)(dian)(dian)解質能(neng)改(gai)(gai)變(bian)微(wei)氣(qi)(qi)泡(pao)(pao)的上(shang)述特性(xing)而影響氣(qi)(qi)浮效果,有(you)人(ren)利用顯(xian)微(wei)電(dian)(dian)(dian)泳(yong)儀測量(liang)了經(jing)有(you)機高分子(zi)(zi)(zi)(zi)物質改(gai)(gai)性(xing)后微(wei)氣(qi)(qi)泡(pao)(pao)的EPM(電(dian)(dian)(dian)泳(yong)遷移率)值(zhi)(zhi)后發現(xian):陽離(li)(li)子(zi)(zi)(zi)(zi)有(you)機高分子(zi)(zi)(zi)(zi)物質可以覆蓋微(wei)氣(qi)(qi)泡(pao)(pao)表(biao)(biao)面(mian)(mian)(mian)而使其(qi)表(biao)(biao)面(mian)(mian)(mian)電(dian)(dian)(dian)荷(he)由負(fu)(fu)(fu)變(bian)正。
1。微氣(qi)泡大小
以往,人(ren)們都認(ren)為微(wei)氣(qi)(qi)泡越小則氣(qi)(qi)浮機(ji)效果越好。但近(jin)來的研(yan)究表(biao)明,這種看法存(cun)在一定的片面性,即微(wei)氣(qi)(qi)泡并不是越小越好,其(qi)原因主要有:
(1)微氣泡(pao)越小則絮體(ti)顆(ke)粒上浮所(suo)需粘附(fu)的微氣泡(pao)個數就(jiu)越多,顯然粘附(fu)更多的微氣泡(pao)比(bi)較(jiao)困難;
(2)微氣泡(pao)在產生過(guo)(guo)程(cheng)中需要克(ke)服其(qi)表面水分子層(ceng)的(de)表面張力而做功(即增加體(ti)系(xi)表面自由能(neng)),這是一個能(neng)量(liang)消耗(hao)過(guo)(guo)程(cheng)。顯然,微氣泡(pao)越(yue)小則能(neng)耗(hao)就越(yue)大;
(3)微氣(qi)(qi)泡越(yue)小則所受(shou)浮力就越(yue)小,越(yue)容易因水流攜(xie)帶作用而通過底(di)部集水系統(tong)進入后(hou)續濾池(造成氣(qi)(qi)阻(zu)等);
(4)微氣(qi)泡(pao)大(da)小(xiao)還受分(fen)離區表(biao)(biao)面(mian)負(fu)(fu)荷制(zhi)約。當氣(qi)浮機表(biao)(biao)面(mian)負(fu)(fu)荷增(zeng)(zeng)大(da)時,泡(pao)絮結(jie)合體(ti)在水中的(de)(de)(de)停留時間縮短,這時只有(you)增(zeng)(zeng)大(da)其上(shang)浮速率才能浮至水面(mian)。顯然,粘附一(yi)定數(shu)量(liang)的(de)(de)(de)小(xiao)氣(qi)泡(pao)比粘附同樣數(shu)量(liang)的(de)(de)(de)較(jiao)大(da)氣(qi)泡(pao)具有(you)更大(da)的(de)(de)(de)表(biao)(biao)觀(guan)相(xiang)對密度和更小(xiao)的(de)(de)(de)上(shang)浮速率,因此(ci)不利于(yu)增(zeng)(zeng)大(da)氣(qi)浮機表(biao)(biao)面(mian)負(fu)(fu)荷。基(ji)于(yu)以上(shang)原因,氣(qi)浮工(gong)藝(yi)中的(de)(de)(de)微氣(qi)泡(pao)大(da)小(xiao)應適當,過大(da)或過小(xiao)都會影(ying)響(xiang)氣(qi)浮
效果。生產(chan)實(shi)踐表明(ming),當表面(mian)負荷(he)約10m2/(m·h)時,控制微氣(qi)泡直徑在10-100mm范(fan)圍內(平(ping)均為40mm左右(you)),就能夠(gou)取得滿意的凈水效果。根據研究結果,當氣(qi)浮機表面(mian)負荷(he)增加到25m2/(m·h)或更大時,微氣(qi)泡的平(ping)均直徑在100mm左右(you)更合適。
2。微氣泡(pao)表面特性
一(yi)般(ban)來說,水(shui)中(zhong)微(wei)氣(qi)(qi)泡(pao)(pao)優先吸附(fu)(fu)(fu)某些負(fu)(fu)(fu)離(li)(li)子(zi)(zi)(zi)(zi)而帶負(fu)(fu)(fu)電(dian)(dian)(dian),相(xiang)應(ying)其(qi)表(biao)(biao)面(mian)(mian)(mian)電(dian)(dian)(dian)位為較(jiao)高負(fu)(fu)(fu)值(zhi)(zhi)。測量(liang)結(jie)果表(biao)(biao)明(ming),氣(qi)(qi)浮機中(zhong)微(wei)氣(qi)(qi)泡(pao)(pao)表(biao)(biao)面(mian)(mian)(mian)電(dian)(dian)(dian)位一(yi)般(ban)在-100mV左右,而絮(xu)體顆粒表(biao)(biao)面(mian)(mian)(mian)電(dian)(dian)(dian)位通常也(ye)為負(fu)(fu)(fu)值(zhi)(zhi),因(yin)此它(ta)們在相(xiang)互靠近時會(hui)存在靜電(dian)(dian)(dian)排斥作(zuo)用而對其(qi)碰(peng)撞粘附(fu)(fu)(fu)過(guo)程產生負(fu)(fu)(fu)面(mian)(mian)(mian)影響。原水(shui)水(shui)質及(ji)吸附(fu)(fu)(fu)的離(li)(li)子(zi)(zi)(zi)(zi)種類(lei)、數量(liang)不(bu)同則(ze)微(wei)氣(qi)(qi)泡(pao)(pao)強(qiang)度、表(biao)(biao)面(mian)(mian)(mian)憎水(shui)性(xing)能(neng)及(ji)電(dian)(dian)(dian)性(xing)等也(ye)有(you)所不(bu)同。向水(shui)中(zhong)添加電(dian)(dian)(dian)解質能(neng)改(gai)(gai)變(bian)微(wei)氣(qi)(qi)泡(pao)(pao)的上(shang)述特性(xing)而影響氣(qi)(qi)浮效果,有(you)人(ren)利用顯(xian)微(wei)電(dian)(dian)(dian)泳(yong)儀測量(liang)了經(jing)有(you)機高分子(zi)(zi)(zi)(zi)物質改(gai)(gai)性(xing)后微(wei)氣(qi)(qi)泡(pao)(pao)的EPM(電(dian)(dian)(dian)泳(yong)遷移率)值(zhi)(zhi)后發現(xian):陽離(li)(li)子(zi)(zi)(zi)(zi)有(you)機高分子(zi)(zi)(zi)(zi)物質可以覆蓋微(wei)氣(qi)(qi)泡(pao)(pao)表(biao)(biao)面(mian)(mian)(mian)而使其(qi)表(biao)(biao)面(mian)(mian)(mian)電(dian)(dian)(dian)荷(he)由負(fu)(fu)(fu)變(bian)正。