Compositions and methods and systems for treating wastewater within a wastewater treatment system of described. In an embodiment, a method for treating wastewater may include adding a magnesium compound to wastewater within a wastewater treatment system. The method may also include adding an effective amount of a dispersing agent and one or more of a free magnesium control agent and a seed material to wastewater within the wastewater treatment system to control the formation of struvite scale within the wastewater treatment system. Other compositions and methods are described.

Disclosed herein are graphene quantum dot tagged water source treatment compounds or polymers, and methods of making and using. Also described herein are tagged compositions including an industrial water source treatment compound or polymer combined with a graphene quantum dot tagged water source treatment compound or polymer. The tagged materials are tailored to fluoresce at wavelengths with minimized correspondence to the natural or “background” fluorescence of irradiated materials in industrial water sources, enabling quantification of the concentration of the water source treatment compound or polymer in situ by irradiation and fluorescence measurement of the water source containing the tagged water source treatment compound or polymer. The fluorescence measurement methods are similarly useful to quantify mixtures of tagged and untagged water source treatment compounds or polymers present in an industrial water source.

A supercritical water oxidation (SCWO) system with a well-mixed SCWO reactor, a feedstock supplied to the well-mixed SCWO reactor by a feedstock supply line, a recirculation loop flow regulator in fluid communication with the well-mixed SCWO reactor; and a recirculation loop which includes the well-mixed SCWO reactor and the recirculation loop flow regulator, such that the recirculation loop flow regulator receives an oxidant from an oxidant supply line and a first portion of a reactor effluent from the well-mixed SCWO reactor and supplies the oxidant and the first portion of the reactor effluent to the well-mixed SCWO reactor. The SCWO system also includes a heat transfer unit operationally associated with the well-mixed SCWO reactor which performs at least one of: heating the well-mixed SCWO reactor and cooling the well-mixed SCWO reactor.

A method and system for operating a seal gas compressor utilized in a direct reduction process including: monitoring a pH level of a water stream used in the seal gas compressor, wherein the pH level of the water stream is affected by a reformer flue gas stream that comes into contact with the water stream, wherein the monitoring step is carried out one or more of upstream of the seal gas compressor and downstream of the compressor; and adjusting the pH level of the water stream to maintain the pH level of the water stream within a predetermined range based on feedback from the monitoring step. The method includes maintaining the pH level of the water stream upstream of the seal gas compressor in a range between 7.5 and 10 and maintaining the pH level of the water stream downstream of the seal gas compressor in a range between 7.8 and 9.5.

Methods and systems are described for monitoring and managing fluid treatment or storage systems, such as HVAC hydronic water systems. Sensors located at a fluid system can detect various types of data, such as chemical amounts, pressures, temperatures, flow rates, and more. Servers in communication with the sensors can record the data and provide it to a user in a variety of graphical interfaces. One useful interface for display of the data includes a five-sided axis called the OPTI-GON.

A method of reducing activity of sulfur and/or nitrogen metabolizing bacteria is provided. The method includes adding a composition of an alkali metal salt of chlorite and/or an alkali metal salt of chlorate and hydrogen peroxide to process water of a cooling tower and increasing a concentration of the composition from about 0 ppm to about 300 ppm in about 1 to about 100 minutes. The method results in significant savings of caustic and reduces sulfur and/or nitrogen metabolizing bacteria in the process water.

Disclosed is a water treatment apparatus including a pipe. Elements disposed in the pipe are respectively made of lead-free brass and nontoxic ultra high molecular weight polyethylene instead of brass and plastic polyethylene that are conventionally used materials. Therefore, when the elements come into contact with water, neither heavy metals, such as lead (Pb), nor organic and inorganic substances harmful to the human body are produced.

Provided herein is a reductive solution for preventing rouge formation on stainless steel, said solution comprising complexing anions, Fe.sup.2+, and, optionally, one or more pH modifiers. Further provided are methods for manufacturing said solution, methods for prevention of rouge formation on stainless steel surfaces, and related uses of the aforementioned reductive solution.

Water treatment compositions are provided that are effective for mitigating corrosion or fouling of surfaces in contact with aqueous systems. The water treatment compositions can include one or more azole compounds, one or more transition metals, and one or more dispersants, in addition to various other additives. The water treatment compositions can exclude phosphorus and still be effective. Methods for mitigating corrosion or fouling of a surface in an aqueous system are also provided.

A SCWO reactor fouling prevention and mitigation system that includes at least one feedstock tee which provides a feedstock to the SCWO reactor, at least one feedstock tee pressure sensor, such that each of the at least one feedstock tee has one of the at least one feedstock tee pressure sensor, at least one pressure sensor proximate a SCWO reactor inlet, and at least one pressure sensor proximate a SCWO reactor outlet. Also included is a controller which triggers a Clean In Place (CIP) procedure when there is a pressure difference between any two of the following, the SCWO reactor inlet, the at least one feedstock tee, and the SCWO reactor outlet. The CIP procedure includes washing a portion of the SCWO reactor with a fluid supplied through the at least one feedstock tee.