A system, method and apparatus for determining and controlling water clarity or water opacity especially useful in pools, spas, and contained bodies of water.

Embodiments of the invention relate generally to methods and systems for treating aqueous systems associated with industrial wastewater applications, in particular gas and crude oil drilling, pumping and production, in order to reduce or eliminate contamination and allow the water that is treated to be reused, in particular, to be reused for hydraulic fracturing.

Disclosed herein are systems and processes for treating a Waste Stream comprising biosolids, the Waste Stream provided at varying flow rates and solids concentrations so as to achieve an SOUR of 1.5 mg O.sub.2/g/hr or less and an ORP of at least +300 mV. The system includes a biosolids manipulation device to adjust the volume of suspended solids as a percent of the total volume of the Waste Stream to five (5) percent or less; a chemical oxidant feed device to dose the Waste Stream with an oxidant such as chlorine dioxide, ozone, or similar oxidant, and a treatment vessel associated with said chemical oxidant feed device through which said Waste Stream flows, wherein said chemical oxidant feed device and said treatment device are configured so as to achieve a dose rate between 25 and 200 parts per million of the Waste Stream and substantially complete mixing of the oxidant within 30 seconds of dose delivery in the treatment vessel.

A system to produce reactive oxidative species in a fluid medium containing a source of Cl(I) by irradiating a solid photocatalyst suspended in the fluid medium or residing on a surface that is contactable by the fluid with electromagnetic radiation. The electromagnetic radiation can be in the UV, near-UV, visible, or near-IR consistent with the photocatalyst employed. The source of Cl(I) in certain embodiments is Cl.sub.2, HOCl, or H.sub.2NCl. The photocatalyst is g-C.sub.3N.sub.4, TiO.sub.2, BBiOBr, or any other solid insoluble photocatalyst.

Embodiments of the invention relate generally to methods and systems for treating aqueous systems associated with industrial wastewater applications and gas and crude oil drilling, pumping and production to reduce or eliminate contamination. In one embodiment, a method includes: an aqueous volume having an initial oxidant demand, an oxygen-containing oxidant and at least one chlorine oxide at substoichiometric amounts in an amount sufficient to eliminate the oxidant demand. The system includes: an aqueous treatment system comprising a containment system; at least one apparatus for introducing an oxygen-containing oxidant; and at least one apparatus for introducing at least one chlorine oxide into said containment system at controlled, substoichiometric quantities.

Embodiments of the invention relate generally to methods and systems for treating aqueous systems associated with industrial wastewater applications, in particular gas and crude oil drilling, pumping and production, in order to reduce or eliminate contamination and allow the water that is treated to be reused, in particular, to be reused for hydraulic fracturing.

Methods of treating contaminated groundwater having recalcitrant organic contaminants are disclosed. The methods include pretreating the contaminated groundwater to remove iron, introducing a persulfate to the contaminated groundwater, and exposing the contaminated groundwater to irradiation. The methods may also include extracting the contaminated groundwater from a feed stream. The methods may also include preparing the persulfate with high purity water. Systems for treating contaminated groundwater having recalcitrant organic contaminants are also disclosed. The systems include a pretreatment subsystem, a source of persulfate, and an irradiation source.

Embodiments of the invention relate generally to methods and systems for treating aqueous systems associated with industrial wastewater applications and gas and crude oil drilling, pumping and production to reduce or eliminate contamination. In one embodiment, a method includes: an aqueous volume having an initial oxidant demand, an oxygen-containing oxidant and at least one chlorine oxide at substoichiometric amounts in an amount sufficient to eliminate the oxidant demand. The system includes: an aqueous treatment system comprising a containment system; at least one apparatus for introducing an oxygen-containing oxidant; and at least one apparatus for introducing at least one chlorine oxide into said containment system at controlled, sub stoichiometric quantities.

A system and method for controlling the accelerated remediation of aquatic facilities using at least one sanitizer sensor, a pH sensor, a temperature sensor and a chlorine dioxide sensor all interfaced with a programmable controller that is programmed to implement a remediation cycle and configured to calculate a Ct value, the sensors being in fluid contact with water of the aquatic facility, and the programmable controller is interfaced with a chemical feed system for supplying chlorine dioxide to the water.

A system and method of treating a fluid to be used for hydraulic fracturing adds an effective amount of chlorine dioxide to the fluid to act as a biocide that kills harmful bacteria. A system for adding chlorine dioxide to the fluid can continuously add chlorine dioxide to an incoming flow of the fluid to produce a continuous flow of treated fluid.