一般来说，处理废水，采用电解、化学沉淀、吸附等方法进行处理，有时为了在自来水中消毒，还参杂了氯气。不管是采用化学法还是生物法，都会出现成本过高或者净化不彻底等问题，那么是否能够寻找到一种既高效又节能环保的方法来处理废水呢？就目前而言，作为废水处理的一个研究热点——强磁分离法来处理废水是很有效。那么，什么是磁分离法？它的原理是怎样的？它能够净化废水到何种程度？
Generally speaking, the wastewater is treated by electrolysis, chemical precipitation, adsorption and other methods, and sometimes chlorine gas is mixed in order to disinfect the tap water. Whether chemical or biological methods are used, there will be problems such as high cost or incomplete purification. Can we find a method that is both efficient and energy-saving and environmental protection to treat wastewater? At present, as a research hotspot of wastewater treatment, strong magnetic separation method is very effective. So, what is magnetic separation? How does it work? To what extent can it purify wastewater?
所谓的磁分离就是根据不同物质具有不同的磁性性质（物质的磁性可分为三种：铁磁性、顺磁性和反磁性，其中铁磁性物质可以作为磁种添加到弱磁性的废水中进行磁分离），当废水中的磁性物质或者非磁性物质（需要添加磁种）处于磁场中时，物质必然会受到来自磁场的作用力，当然，废水中的悬浮不仅受磁场力，还受到重力、流体黏滞力、流体惯性力以及分子间的吸引力，只要我们所施加的磁场足够大，就可以使得废水中的悬浮颗粒进行磁分离。
The so-called magnetic separation is based on the fact that different substances have different magnetic properties (the magnetism of materials can be divided into three types: ferromagnetism, paramagnetism and diamagnetism, in which ferromagnetic materials can be added to the weak magnetic wastewater for magnetic separation). When the magnetic materials or non-magnetic materials in the wastewater (need to add magnetic seeds) are in the magnetic field, the materials will inevitably be affected Of course, the suspension in wastewater is not only affected by magnetic field force, but also by gravity, fluid viscosity, fluid inertia force and intermolecular attraction. As long as the magnetic field applied is large enough, the suspended particles in wastewater can be separated by magnetic field.
而磁分离的方法又可以采用永磁分离和电磁分离（包含超导磁分离）。磁力大小的公式为Fu=γVH(dH/dx)，其中，γ为颗粒本身磁化率，V为颗粒体积，H为磁场强度，dH/dx为磁场强度梯度。从实际应用中来考虑，如果我们单纯的用永磁体增加磁场强度，的确可以增加磁场力的大小，但是这样所制造的磁铁太耗成本。因此大多采用磁梯度分离法，即只需要增加磁场强度的梯度，就可以达到增强磁场力的效果。值得一提的是，要想产生高强度的磁场，用一般的永磁铁，很难实现，可以采用超导体来实现，理论上处于临界温度以下的超导体所产生的磁场强度可以达到10T以上，可以在无需添加磁种的情况下就能轻松实现磁分离。一般的梯度磁分离可分离微细颗粒（线度1um）和弱磁性微粒（磁化率低到10-6），那么，超导梯度磁分离的范围和精度将比此更广，更精确。

And the magnetic separation method can use permanent magnetic separation and electromagnetic separation (including superconducting magnetic separation). The formula of magnetic force is Fu = γ VH (DH / DX), where γ is the magnetic susceptibility of the particle itself, V is the volume of the particle, h is the magnetic field strength, and DH / DX is the magnetic field intensity gradient. Considering from the practical application, if we simply use permanent magnet to increase the magnetic field strength, we can indeed increase the size of magnetic field force, but the magnet made in this way consumes too much cost. Therefore, the magnetic gradient separation method is mostly used, that is, only increasing the gradient of magnetic field intensity can achieve the effect of enhancing magnetic field force. It is worth mentioning that in order to generate high-intensity magnetic field, it is difficult to achieve with ordinary permanent magnet. Superconductor can be used to achieve. Theoretically, the magnetic field strength of superconductor below critical temperature can reach more than 10t, which can easily realize magnetic separation without adding magnetic seeds. The general gradient magnetic separation (GMS) can separate fine particles (linear 1 um) and weakly magnetic particles (magnetic susceptibility as low as 10-6), so the scope and accuracy of superconducting gradient magnetic separation will be wider and more accurate.
无疑，磁分离技术在废水处理中不仅高效环保，而且造价和维护成本低，作为一般的磁分离的加强版——超导磁分离技术将大大提升常导磁分离的性能。我们有理由相信，随着科学家对磁体、污染物的分离程度的机制等方面的不断研究，磁分离技术将被应用到寻常百姓家中。
Undoubtedly, magnetic separation technology is not only efficient and environmentally friendly in wastewater treatment, but also has low cost and maintenance cost. As an enhanced version of general magnetic separation, superconducting magnetic separation technology will greatly improve the performance of normal magnetic separation. We have reason to believe that magnetic separation technology will be applied to ordinary people's homes with the continuous research on magnets and the mechanism of the degree of separation of pollutants.