A system and method for monitoring process water treated with a biocide is provided. The system includes a biocide feeding unit and a dissolved oxygen sensor. The dissolved oxygen sensor works in two modes, a biocide feeding mode and a background mode, and alerts an operator when the dissolved oxygen value indicates a fault in the system. A drop in dissolved oxygen during feeding can indicate faulty production of biocide or biocide degradation, both of which can lead to unwanted disinfection by-products.

A membraneless electrochemical device comprises a fluid feed stream input to the membraneless electrochemical cell, a first electrode, and a second electrode. The first electrode comprises a first redox-active material configured to have a proton-coupled oxidation reaction with a first portion of the fluid feed stream, and the second electrode comprises a second redox-active material configured to have a proton-coupled reduction reaction with a second portion of the fluid feed stream. The first portion and the second portion of the fluid feed stream are separated. A first effluent stream comprises the first portion and has a first pH, and a second effluent stream comprises the second portion and has a second pH, different from the first pH.

A unit (8) is intended for treating waste water. It includes a well (9) with an inlet conduit connector (21) and with an outlet conduit connector (22) at the outside of the well (9). The unit further includes a connecting conduit (20) inside the well (9). The connecting conduit (20) connects the inlet conduit connector (21) to the outlet conduit connector (22). There is at least one storage tank (13) inside the well (9) for a liquid chemical and a metering pump (18) inside the well (9) for pumping the chemical from the storage tank (13) into the connecting conduit (20). A control device (23) activates the metering pump according to a signal of a sensor (24) which senses a quantity of chemical element in the liquid flowing through the conduit (20).

A method and system of treating a liquid stream is provided. The water is treated by utilizing a free radical scavenging system and a free radical removal system. The free radical scavenging system can utilize actinic radiation with a free radical precursor compound, such as ammonium persulfate. The free radical removal system can comprise use of a reducing agent. The water may be further treated by utilizing ion exchange media and degasification apparatus. A control system may be utilized to measure and regulate addition of the precursor compound, the intensity of the actinic radiation, and addition of the reducing agent to the water.

Systems and method for treating wastewater including a vessel having an inlet and an outlet, a pump in fluid communication with the outlet of the vessel, the pump configured to pump wastewater out of the vessel, a separator in fluid communication with the pump, the separator configured to separate grit from the wastewater, the separator having a first outlet for discharging a grit stream and a second outlet for discharging a wastewater stream, a grit washing system in fluid communication with a source of washing fluid and the first outlet of the separator, the grit washing system configured to wash and dewater grit from the grit stream, the grit washing system having an outlet for discharging a wash wastewater stream, and a return conduit configured to recycle the wastewater stream discharged from the separator to one of the inlet of the vessel and an inlet to the pump.

Provided are systems and methods for treating wastewater with a continuous-process mobile station. The mobile station may include one or more mobile units configured to receive a feed of wastewater. The one or more mobile units may include: a mobile ozonation unit configured to treat the received feed of wastewater with ozone gas to breakdown impurities in the wastewater, a pH control unit may be configured to raise pH of the treated wastewater, a mobile electrocoagulation unit configured to separate solids and metals from the treated wastewater, a mobile flocculation unit configured to cause suspended particles to form flocs and to remove the flocs from the received treated water.

A method of controlling addition rate of an odor control chemical to a wastewater line by adding odor control chemical to the wastewater. The method includes measuring a level of dissolved sulfides in the wastewater line using a sulfide probe placed in said wastewater line, transferring data on the level of dissolved sulfides to a computing unit, determining a required odor control chemical addition rate in said computing unit based on said level of dissolved sulfides, and adding the odor control chemical at said required addition rate. The method allows for accurate on-line control of the level of H.sub.2S in the wastewater line.

A scale suppression apparatus capable of suppressing in a low-priced manner the generation of silica-based scale and calcium-based scale in the influent water containing at least a silica component and a calcium component, a geothermal power generation system using the same, and a scale suppression method are provided. The scale suppression apparatus includes a chelating agent and alkaline agent addition unit injecting liquid containing a chelating agent and an alkaline agent into a pipe arrangement through which influent water such as geothermal water or the like flows, and a controller controlling a pump and a valve of the chelating agent and alkaline agent addition unit. The controller controls the injection of the chelating agent and the alkaline agent and stops of the injection based on the signal output from a scale detection unit for detecting a precipitation state of the scale.

Disclosed are methods of monitoring the presence of naphthenic acids and related compounds. In particular, the invention provides a method of continuously monitoring naphthenic acids and related compounds that break through a filtration step in a wastewater treatment process.

A water treatment filter backwash process control system, comprising a control system that receives filter level data and filter backwash turbidity data. The control system having a filter level set point, wherein the filter level set point corresponds to a desired filter media bed expansion. The control system having a filter backwash turbidity set point, wherein the control system controls the filter backwash process by, while monitoring the filter backwash turbidity, sending one or more output signals that are used to control a backwash inlet liquid flow in order to maintain a desired media bed expansion, and stop the backwash inlet liquid flow when the filter backwash turbidity set point is reached.