【正文】 以 用來(lái) 從水中 除去鹽 和和其他 溶解固體 ：蒸餾 、 反滲透 (RO)、 電滲析 (ED)、 離子交換 (IX)和 凍淡化。 RO 和 ED 使用膜 技術(shù) 從水中分 離了 溶解的鹽和礦 物質(zhì)。世界 范圍內(nèi)不同類型的淡化工廠所占的相對(duì)百分?jǐn)?shù)用 表格 2 表示 。在 20 世紀(jì) 50 年代 初 全世界約 有225 座 基于土地的淡化 工廠，其綜合容量 大約 為 27 mdg, 全世界在運(yùn)行中的超過7500 座淡化工廠中， 有 60%位于中東。相反，世界 容量 的 12%在 美國(guó) 產(chǎn)生 ，大多數(shù) 工廠 位于加勒比海和佛羅里達(dá) [4]. 圖 1 表示了海水中鹽的濃縮。 給水 要經(jīng)過預(yù)處理 除去 對(duì) 膜 有 阻塞 作用 的粒子。允許陽(yáng)離子通過的膜 與 可滲透陰離子的膜 輪流替換 [7].通過穿過成堆的離子膜的電極，在離子膜堆之間產(chǎn)生了直流電。部分脫鹽的水 則 在臨近的套膜對(duì)之間留下。這 就改變了 離子通過膜的流 向，這樣 收集咸濃縮物的空間開始收集較少 的 咸水。 電滲析 對(duì) 典型淡水恢復(fù)速率 (反向 )為供給水的 80%90%范圍內(nèi) 。 在供給水中 溶解 的 固體 濃度 越高，樹脂 也就越 需要被 經(jīng)常 替換 或者再生。 . 凍淡化 當(dāng) 咸水 結(jié)冰時(shí)，冰從純水 中 結(jié)晶， 而 溶解的鹽和其他礦 物質(zhì)則留在了 高鹽 區(qū)域 。 傳統(tǒng)的結(jié)冰的過程包含 5 步： ? 供給水的 預(yù)先煮沸； ? 半融的冰水中 冰的結(jié)晶 ； ? 來(lái)自鹽水的冰的分離 ； ? 洗冰 ； ? 融化冰。雖 然 小規(guī)模的 結(jié)冰在 20 世紀(jì) 60 年代后期 已經(jīng)有所嘗試 ，但是仍然有重要的操作問題 ，現(xiàn)在 只有一些獨(dú)立的商業(yè) 性的冰凍工廠 存在。 pH 值可能 根據(jù) 章程 的 限制 ，或是按所 要求 的 具體的水平 進(jìn)行調(diào)整，直到 消除下水道附加費(fèi)或者罰款。系統(tǒng)替換 了 對(duì)大的油箱 、 苛性的噴頭和混和器的需要，用一個(gè)非常小自動(dòng)化的系統(tǒng) 進(jìn)行了 替換。進(jìn)入河和溪的化學(xué)污染 造成了 驚人的 破 壞。 一般來(lái)講廢水處理的主要目標(biāo)是人類生活 和工業(yè)廢水 得到處置，對(duì) 人 類的 健康 不造成危害， 對(duì)自然的環(huán)境 不造成難以接受 的損害。 但是 ，在被用于工業(yè) /農(nóng)業(yè)目的之前， 對(duì)源 市政廢水通常 必須進(jìn)行 某種程度 的 處理 。在一些處理過程中 為了 從廢水 中 除去營(yíng)養(yǎng) 物質(zhì) 高級(jí)處理是必要 的 。 操作和 運(yùn)行費(fèi)用相對(duì)昂貴 ，并且出水質(zhì)量 對(duì)操作的質(zhì)量 是很 敏感的 。 經(jīng)過 訓(xùn)練并且 取得證書的 處理 廠 操作者測(cè)量并且監(jiān)控來(lái)水 、 處理 過程 和 出水 。 參考 文獻(xiàn) [1] Metcalf 和 Eddy， 廢水工程：處理 ，處置，重復(fù) 使用。 [3] 國(guó)際開發(fā)協(xié)會(huì)，工廠存貨清單， 1987。 [5] ，聚合物科學(xué)膜工程百科全書， 1987 [6] 汽壓，沸騰的一個(gè)解決辦法， [7] . Ho 和 . Li，膜處理， 佩里 化學(xué)工程手冊(cè)，第 6版，紐約， 1984。 Developments in wastewater treatment methods Amit Sonune*, Rupali Ghate Water and Land Management Institute, PO No. 504, Paithan Road, Aurangabad 431005 (MS), India Received 10 February 2020。 Primary treatment。 Membrane technology。 Reuse。Eau Potable, Marrakech, Morocco, 30 May2 June, 2020. 00119164/04/$ See front matter 169。 I. Introduction Water covers 71% of the earth39。 and after we have used it and contaminated it most of it returns to these locations. This used water is called wastewater. If it is not treated before being discharged into waterways, serious pollution is the result. Wastewater may be defined as a bination of liquid or watercarried waste removed fro residences, institutions, and mercial and industrial establishments, together with ground water, surface water and storm water. It generally contains a high load of oxygen demanding wastes, pathogenic or diseasecausing agents,organic materials, nutrients that stimulate plant growth, inorganic chemicals and minerals and sediments. It may also contain toxic pounds[1]. Wastewater may be classified into four categories: ? domestic: wastewater discharged from residences and mercial institutions and similar facilities。 ? infiltration/inflow: extraneous water that enters the sewer system through indirect and direct means such as through leaking joints, cracks, or porous walls. Inflow is storm water that enters the sewer system from storm drain connections, roof headers, foundation and basement drains or through manhole covers。 secondary treatment, which entails oxidation of dis solved organic matter by means of using biologically active sludge, which is then filtered off。 wastewater can be pretreated for discharge to municipal treatment sources。 air filters, water filters, and even drinkable water retraction system for astronauts travelling in space are some of the typical applications. . Desalination technologies Desalination is a process that removes dissolved minerals (including but not limited to salt)from seawater, brackish water, or treated wastewater. There are five basic techniques that can be used to remove salt and other dissolved solids from water: distillation, reverses osmosis (RO),electrodialysis (ED), ion exchange (IX), and freeze desalination. Distillation and freezing involve removing pure water, in the form of water vapor or ice, from salty brine. RO and ED use membranes to separate dissolved salts and minerals from water. IX involves an exchange of dissolved mineral ions in the water for other,more desirable dissolved ions as the water passes through chemical resins. The relative percentages of different types of desalination plants worldwide are shown in Table 2. Over the last few decades desalination technologies have been used increasingly throughout the world to produce drinking water from brackish groundwater and seawater, to improve the quality of existing supplies of fresh water for drinking and industrial purposes, and to treat industrial and municipal wastewater prior to discharge or reuse. In the early 1950s there were about 225 landbased desalination plants worldwide with a bined capacity of about 27 mgd. Of the more than 7,500 desalination plants in operation worldwide, 60% are located in the Middle East. The world39。s capacity is produced in the Americas, with most of the plants located in the Caribbean and Florida [4]. Fig. 1 shows the salt concentration of seawater. . Reverse osmosis (RO) In RO, feed water is pumped at high pressure through permeable membranes, separating salts from the water (Fig. 2). The feed water is pretreated to remove particles that would clog the membranes. The quality of the water produced depends on the pressure, the concentration of salts in the feed water, and the salt permeation constant of the membranes [5]. Osmosis depends only on the solute concentration and not on its type [6]. . Electrodialysis (ED) Table 2 Relative distribution of different types of desalination plants worldwide Source: International Desalination Association [3]. With this technique, brackish water is pumpedat low pressures between several hundred flat,parallel, ionpermeable membranes that are assembled in a stack. Membranes that allow cations to pass through them are alternated with anionpermeable membranes [7]. A direct electrical current is established across the stack by electrodes positioned at both ends of the stack. This electric current pulls3