The present disclosure provides methods, electrodes, and systems for electrochemical oxidation of polyfluoroalkyl and perfluroalkyl (PFAS) contaminants using Magnéli phase titanium suboxide ceramic electrodes/membranes. Magnéli phase titanium suboxide ceramic electrodes/membranes can be porous and can be included in reactive electrochemical membrane filtration systems for filtration, concentration, and oxidation of PFASs and other contaminants.

A method and system of providing ultrapure water for semiconductor fabrication operations is provided. The water is treated by utilizing a free radical scavenging system. The free radical scavenging system can utilize actinic radiation with a free radical precursor compound, such as ammonium persulfate. The ultrapure water may be further treated by utilizing ion exchange media and degasification apparatus. A control system can be utilized to regulate a continuously variable intensity of the actinic radiation.

A method of removing fluoride ion from waste liquid is provided, which includes providing a calcium source and a plurality of ceramic particles to a waste liquid containing fluoride ion for forming a plurality of calcium fluoride layers wrapping the ceramic particles. The calcium fluoride layers are connected to form a calcium fluoride bulk. The ceramic particles are embedded in the calcium fluoride bulk. The ceramic particles and the calcium fluoride bulk have a weight ratio of 1:4 to 1:20.

Described are filter materials having polycarboxyl ligands, such as iminodiacetic acid, which are highly effective for filtering metals or metal ions from fluids. The filter materials can be particularly useful to filter various fluid compositions, such as those used for wet etching, removing photoresist, and cleaning steps in microelectronic device manufacturing.

An ultrapure water supplying apparatus may include an activated carbon filtering device, an ion exchange resin device connected to the activated carbon filtering device, a reverse osmotic membrane device connected to the ion exchange resin device, a hollow fiber membrane device connected to the reverse osmotic membrane device, a first fluid driving part between the reverse osmotic membrane device and the hollow fiber membrane device, and a control unit configured to control the first fluid driving part. The first fluid driving part may include first, second, and third pumps, which are connected in parallel to the reverse osmotic membrane device, and a pressure sensor located between the first pump and the hollow fiber membrane device. The control unit may be configured to control each of the first, second, and third pumps, based on a signal transmitted from the pressure sensor.

A waste fluid treatment apparatus includes a sedimentation tank that stores the processing waste fluid with the processing debris contained therein, an inflow port provided on the sedimentation tank for introduction of the processing waste fluid into the sedimentation tank, an acidification unit configured to acidify the processing waste fluid to be introduced from the inflow port into the sedimentation tank, whereby the processing debris is allowed to settle at a higher rate compared with a rate at which the processing debris would settle if the processing waste water is neutral, and an outflow port provided on the sedimentation tank for discharge of acidic supernatant that is obtained by allowing the processing debris in the processing waste fluid to settle in the sedimentation tank from the sedimentation tank.

A method for starting up a hot ultrapure water production system that produces hot ultrapure water by heating ultrapure water to a supply water temperature, for supplied to a point of use, the method involving: alternately passing heated water and cooled water through a hot ultrapure water pipe through which the hot ultrapure water flows, the heated water being obtained by heating the ultrapure water to a temperature higher than room temperature and the cooled water being obtained by cooling the ultrapure water to a temperature lower than the temperature of the heated water in a range of from room temperature to the supply water temperature.

Described are filter materials including a polyol ligand, such as n-methylglucamine, and/or a polyphosphonic acid ligand, which are highly effective for filtering metals or metal ions from fluids. The filter materials can be particularly useful to filter basic and acidic fluid compositions, such as those used for wet etching, removing photoresist, and cleaning steps in microelectronic device manufacturing.

A microbial carrier and a device for treating wastewater are provided. The microbial carrier includes a bacteriophilic material and a plurality of foam cells, wherein the foam cells are disposed in the bacteriophilic material. The bactericidal material is a reaction product of a composite, wherein the composition includes a hydrophobic polyvinyl alcohol and a cross-linking agent, wherein the surface energy of the hydrophobic polyvinyl alcohol is 30 mJ/m.sup.2 to 58 mJ/m.sup.2.

Provided are an ozone water decomposition apparatus and method that can decompose ozone water quickly and stably. The ozone water decomposition apparatus, comprising: a tank configured to accommodate ozone water and decompose the ozone water; a first supply unit configured to supply the ozone water to the tank; a second supply unit configured to supply an additive to the tank wherein the additive is supplied by a preset first or second supply amount; a circulation line configured to circulate the ozone water in the tank; and a concentration meter installed in the circulation line, wherein the ozone water decomposition apparatus comprises: after circulating the ozone water using the circulation line, measuring an ozone concentration of the ozone water using the concentration meter; subsequently supplying the additive of the first supply amount or the second supply amount based on the measured ozone concentration of the ozone water; and subsequently circulating the ozone water until the ozone concentration of the ozone water reaches a preset reference concentration.