The present invention concerns a method for cleaning a filtration system under operation. The filtration system comprising a hydraulic circuit Cp recycling the permeate stream to the feed side of the membrane and/or a hydraulic circuit Cr recycling the retentate stream to the feed side of said membrane. The method comprises injecting an amount of a chemical product into the filtration system in the hydraulic circuit Cp or in the hydraulic circuit Cr or upstream of the cross-flow filtration membrane, setting the proportion of recycled permeate stream or recycled retentate stream collected in the hydraulic circuit Cp and/or Cr to enable the recycling of a significant amount of unreacted chemical product having passed through said cross-flow filtration membrane to the feed side of said cross-flow filtration membrane, as well as a filtration system for carrying out said method.

The invention relates to a method and a system for controlling a membrane separation unit of an aqueous liquid effluent treatment plant comprising a system for injecting at least one chemical compound into the effluent to be treated. The method and the system allow regulating at least one parameter selected from an amount of chemical compound(s) to be added and a conversion rate in order to avoid clogging and/or precipitation of ionic species in the retentate. This regulation uses optimum setpoint values determined according to one or more parameter(s) characteristic of the retentate and not of the water to be treated. Thus, an accurate regulation of the amount of chemical compound(s) to be added and/or of the conversion rate of the membrane separation unit at an optimum value allowing at the same time avoiding clogging and/or precipitation of the species likely to precipitate and minimising the operating costs is achieved.

A fully contained water treatment plant for removal of PFAS chemicals. The portable plant will allow engineers to select or modify 11 steps or stages of treatment to suit their particular water source needs. The water treatment plant combines multiple treatment methods into one synergistic process including: Advanced Oxidation (Ozone and UV), Media filtration, and reverse osmosis membrane technologies. The synergistic effect of the combined methods into one specific process will remove 99% of PFAS/PFOS chemicals and can be used to receive contaminated water from oceans, lakes, rivers, or aquifers.

An example water purification system for purifying high concentration feed solutions includes a high rejection forward osmosis module, one or more low rejection modules, and a high rejection reverse osmosis module. The low rejection modules may have different rejection levels. The system may be pressurized by one or more pumps. One or more of the low rejection modules may include one or more nanofiltration (NF) membranes. The draw solution may comprise a monovalent salt, a multivalent salt, or a combination of both.

The water treatment device according to the present disclosure includes: an electrochemical cell having electrodes including a positive electrode and a negative electrode, and a bipolar membrane; a tank; a power supply configured to apply power to the electrodes; a water circulation flow path having at least the tank and the electrochemical cell and through which water circulates; a circulation device configured to circulate water in the water circulation flow path; a raw water supply path configured to supply raw water to the water circulation flow path; and a control device. In performing water softening treatment in the electrochemical cell where power is applied to the electrodes so as to remove ions from raw water and soft water is produced, the control device drives the circulation device so as to circulate water in the water circulation flow path.

A method for operating a membrane separation device includes (a) setting a flow amount M(t) of permeated water and extracting the permeated water from the membrane separation device by the set flow amount M(t), and (b) temporarily stopping the extracting the permeated water, when a water level of a first water tank in which the membrane separation device is immersed, a water level of a second water tank in communication with the first tank, or a water level of a third water tank receiving overflowing water from the first water tank becomes lower than a predetermined halt water level. M(t), which is the flow amount of the permeated water during a time period t, satisfies a equation M(t)=KQ(t?1), where K is a gain (K>1), and Q(t?1) is an amount of inflow of the water-to-be-treated during a time period t?1 immediately prior to the time period t.

Embodiments of the present disclosure relate to methods of treating carbon molecular sieve (CMS) membranes, and in particular CMS hollow fiber membranes, that have undergone aging-induced permeance/permeability loss. By treating aged CMS membranes in accordance with embodiments of the present disclosure, the CMS membranes may be regenerated such that the aging-induced permeance/permeability loss is reversed and the permeance/permeability of the CMS membrane is increased. In some embodiments, the permeance/permeability of the treated CMS membrane may be increased to such a degree that the permeance/permeability of the regenerated CMS membrane is at least as high as the original permeance/permeability of the CMS membrane prior to aging-induced permeance/permeability loss.

An object of the present invention is to provide a specific method for determining the fouling potential of an activated sludge solution on the basis of the characteristics of the activated sludge solution after chemical cleaning of a membrane, and to provide a suitable method for resuming operation in a rational manner after chemical cleaning of the membrane, while accurately determining the degree of recovery of the membrane filtration characteristics for the activated sludge solution. Moreover, an object of applying the present invention is to enable more effective suppression of an increase in a transmembrane pressure difference after chemical cleaning than in the prior art, leading to a reduction in the cleaning frequency of the membrane and a reduction in the used amount of cleaning chemicals and to extension of the life of the membrane.

The present invention relates to a method for operating a membrane-separation activated sludge treatment device after chemical cleaning of a membrane, the method including, after the chemical cleaning of the membrane is completed, controlling an operating condition until a normal filtration operation is resumed on the basis of characteristics of an activated sludge solution.

A reverse osmosis treatment apparatus includes a membrane unit including an osmosis membrane module. The membrane unit includes a plurality of banks connected in series, each bank including an osmosis membrane module. At least one of the banks includes a treatment water pipe valve and a concentrated water pipe valve, and a bypass pipe capable of diverting the water to be treated, which is to be supplied to the bank, around the bank and draining the water to be treated and a chemical cleaning pipe capable of supplying the reverse osmosis membrane module disposed in the bank with chemical cleaning water are connected. A reverse osmosis treatment method is for cleaning intermittently a bank having the treatment water pipe valve and the concentrated water pipe valve while continuing the reverse osmosis treatment using the remaining bank.

Membrane filtration systems can be used to purify liquid streams for downstream use. In practice, foulant can build-up on the surface of a membrane within a filtration system over time. The effectiveness of the filtration system will deteriorate if the fouling is not properly controlled. In some examples, a method of controlling membrane fouling in a pressurized membrane system involves supplying a feed stream that is predominately air mixed with water to the membrane. In other words, the feed stream a greater volume of air than water, even though it is the water being processed by the membrane. Supplying the pressurized membrane system with a feed stream that contains a greater volume of air than water can yield significantly better performance than supplying the membrane with a feed stream that contains a greater volume of water than air.