A method for removing silica includes treating feedwater with Mg at a high pH, inputting treated feedwater to an optional reactor, pumping the feedwater to a ceramic membrane in a first direction, removing precipitated solids with the ceramic membrane, and removing the precipitated solids from the ceramic membrane.

Provided is a method for operating an RO-membrane treatment system that includes an energy recovery device that recovers energy from the concentrate of an RO-membrane device and the RO-membrane treatment system that reduce the occurrence of biofouling in not only the RO-membrane device but also the energy recovery device in order to increase the energy efficiency of the entire system and operate the RO-membrane treatment system with consistency. The method includes adding at least one slime-control agent selected from a combined-chlorine slime-control agent and a stabilized-bromine slime-control agent to water that is to be treated with the reverse-osmosis-membrane device such that a residual halogen concentration in the concentrate that is to be introduced into the energy recovery device is 0.1 to 10000 mg/L as total chlorine.

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.

This disclosure relates to a combination for inhibiting or removing biofouling and a method for inhibiting biofouling growth or removing biofouling. This disclosure also relates to a combination including halogen-type oxidizers, sulfur-containing compounds, and ammonium salts and/or urea. Also disclosed are methods for inhibiting the biofouling growth in a reverse osmosis membrane separation device or nanofiltration membrane separation device or removing the biofouling in a reverse osmosis membrane separation device or nanofiltration membrane separation device.

A method for controlling slime is used in a reverse osmosis membrane apparatus and has a water-supplying step of supplying water to be treated to the reverse osmosis membrane. The water-supplying step includes a first water-supplying step in which a slime controlling agent X which contains 2,2-dibromo-3-nitrilopropionamide (DBNPA) and a slime controlling agent Y which contains at least one type selected from a group consisting of components (A) to (D) are added to the water to be treated which has a pH of 10 or less, and the water to be treated which contains the slime controlling agent X and the slime controlling agent Y is supplied to the reverse osmosis membrane. The component (A) is mixture of 5-chloro-2-methyl-4-isothiazolin-3-one (Cl-MIT) and 2-methyl-4-isothiazolin-3-one (MIT), the component (B) is chloramine compound, the component (C) is stabilized bromide, and the component (D) is glutaraldehyde.

The invention concerns a subsea water processing system comprising an electrochemical unit that uses raw or treated seawater to generate high pH and low pH solutions that are used to clean at least one subsea process apparatus during a cleaning cycle by circulation through the at least one subsea process apparatus via acid or base flow lines connecting the electrochemical unit with the subsea process apparatus on-site.

The invention relates to a filtration system (10) for liquid, particularly raw water, comprising at least one filtration module (20) for filtering the liquid, a first inlet pipe (21) for feeding liquid to the filtration module (20), a second inlet pipe (22) for feeding liquid to the filtration module (20) and at least one outlet pipe (26) for discharging filtrate from the filtration module (20). A cleaning branch (80) is arranged between the first inlet pipe (21) and the second inlet pipe (22), and at least one dosing feeder (81, 82, 83) for adding a cleaning chemical is connected to the cleaning branch (80). The invention also relates to a method for chemical rinsing a filtration system (10) for liquid, particularly raw water, comprising at least one filtration module (20) for filtering the liquid, a first inlet pipe (21) for feeding liquid to the filtration module (20), a second inlet pipe (22) for feeding liquid to the filtration module (20) and at least one outlet pipe (26) for discharging filtrate from the filtration module (20). In chemically rinsing operation, a cleaning chemical is added via a dosing feeder (81, 82, 83) connected to a cleaning branch (80) which is arranged between the first inlet pipe (21) and the second inlet pipe (22).

Provided is a cleaning agent capable of preventing a reduction in the rejection rate of an RO membrane which may occur when the membrane is cleaned, the cleaning agent including a membrane protectant that is a basic or hydrophobic amino acid, a peptide containing the amino acid as a constituent amino acid, or a derivative of the amino acid or the peptide. The cleaning agent may further include at least one agent selected from the group consisting of an alkaline agent, a combined chlorine agent, and an oxidizing agent. The amino acid is preferably arginine, lysine, or phenylalanine. Also provided are a cleaning liquid that is an aqueous solution produced by diluting the cleaning agent and a method for cleaning a reverse osmosis membrane with the cleaning liquid.

A method of producing a sugar liquid includes filtering a cellulose-derived sugar liquid through one or more separation membranes selected from the group consisting of an ultrafiltration membrane, a nanofiltration membrane and a reverse osmosis membrane and washing the separation membrane(s) after filtration with washing water containing an alkaline substance and an aromatic compound at 10? C. or more and less than 50? C.

Provided is a reverse osmosis membrane cleaning apparatus (10) which includes a membrane module (1) including a reverse osmosis membrane, a cleaning water tank (11) which stores cleaning water, a heater (13) which heats cleaning water supplied from the cleaning water tank (11) to the reverse osmosis membrane, and a temperature control device (17) which controls the heater so that a temperature of the cleaning water heated by the heater (13) is higher than 45? C. and not higher than 60? C.