The invention disclosed herein relates to an odor control system including features to allow a media scrubber to function to treat a humid, or saturated, or superheated exhaust stream. In some embodiments, the system disclosed herein can capture a humid, or saturated, or superheated exhaust stream, such as from a kettle vent, and dilute the exhaust with fresh air to lower the temperature of the combined air flow below its dew point. Water is drained from the system as it condenses in the system. The combined air flow can be further diluted and/or treated according to embodiments disclosed herein such that the exhaust stream, after having excess water removed, will have a relative humidity (RH) value enabling it to be run through a media scrubber.

An absorbent liquid which absorbs at least one of CO.sub.2 and H.sub.2S from a gas, including a secondary linear monoamine; a tertiary linear monoamine or a sterically hindered primary monoamine; and a secondary cyclic diamine, wherein a concentration of each of the secondary linear monoamine, the tertiary linear monoamine or the sterically hindered primary monoamine; and the secondary cyclic diamine is less than 30% by weight.

Processes, systems, and associated control methodologies are disclosed that control the flow of biogas during the biogas cleanup process to create a more consistent flow of biogas through the digester, while also optimizing the output and efficiency of the overall renewable natural gas facility. In representative embodiments, a biogas buffer storage system may be used during the cleanup process to control the pressure and flow rate of biogas. The biogas buffer storage system may monitor and control the biogas flow rate to either bring down or increase the digester pressure, thereby maintaining a normalized biogas flow rate.

Processes, systems, and associated control methodologies are disclosed that control the flow of biogas during the biogas cleanup process to create a more consistent flow of biogas through the digester, while also optimizing the output and efficiency of the overall renewable natural gas facility. In representative embodiments, a biogas buffer storage system may be used during the cleanup process to control the pressure and flow rate of biogas. The biogas buffer storage system may monitor and control the biogas flow rate to either bring down or increase the digester pressure, thereby maintaining a normalized biogas flow rate.

Animal litter boxes are provided which include a sensor to detect a change in an environment within an interior of its housing and an odor removal device (ORD) operationally connected to the sensor such that the ORD is activated in response to a signal from the sensor. In some cases, the ORD is configured to operate in different manners based on respectively different signals from the sensor. In addition or alternatively, the litter boxes may include a timer configured with the sensor for activating and periodically reactivating the ORD at preset time intervals in response to a sensor signal. In yet other embodiments, the litter boxes may additionally or alternatively include a timer having user adjustable settings of different time periods at which to initiate activation of the ORD and/or user adjustable settings of different durations at which to operate the ORD, both in response from a sensor signal.

Process for preparing a catalyst or a trapping mass comprising the following steps: bringing a porous oxide support into contact with a metal salt comprising at least one metal belonging to groups VIB, VIIB, VIIIB, IB or IIB, of which the melting point of said metal salt is between 20° C. and 150° C., for a period of between 5 minutes and 5 hours in order to form a solid mixture, the weight ratio of said metal salt to said porous oxide support being between 0.1 and 1; heating the solid mixture with stirring at a temperature between the melting point of said metal salt and 200° C. and for 5 minutes to 12 hours; calcining the solid obtained in the preceding step at a temperature above 200° C. and below or equal to 1100° C. under an inert atmosphere or under an oxygen-containing atmosphere.

A process for hydrotreating a feed stream comprising a biorenewable feedstock is disclosed. The process comprises hydrotreating the feed stream in the presence of a hydrotreating hydrogen stream and a hydrotreating catalyst to provide a hydrotreated stream. The hydrotreated stream is separated into a hydrotreated liquid stream and a hydrotreated gas stream. The hydrotreated liquid stream is subjected to stripping to provide a stripper off-gas stream. At least a portion of the stripper off-gas stream is contacted with a caustic stream to provide a sulfur-lean gas stream and a sulfur-rich caustic stream. The sulfur-rich caustic stream is further treated to provide a treated gas stream.

A process for hydrotreating a feed stream comprising a biorenewable feedstock is disclosed. The process comprises hydrotreating the feed stream in the presence of a hydrotreating hydrogen stream and a hydrotreating catalyst to provide a hydrotreated stream. The hydrotreated stream is separated into a hydrotreated liquid stream and a hydrotreated gas stream. The hydrotreated liquid stream is subjected to stripping to provide a stripper off-gas stream. At least a portion of the stripper off-gas stream is contacted with a caustic stream to provide a sulfur-lean gas stream and a sulfur-rich caustic stream. The sulfur-rich caustic stream is further treated to provide a treated gas stream.

An alkaline aqueous ferric iron salt solution is disclosed. Generally, the alkaline aqueous ferric iron salt solution comprises ferric ions (Fe.sup.3+), potassium ions (K.sup.+), carbonate ions (CO.sub.3.sup.2−), bicarbonate ions (HCO.sub.3.sup.−), hydroxide ions (OH.sup.−), optionally nitrate ions (NO.sub.3.sup.−). Further, a molar ratio of the potassium ions to the ferric ions is generally at least 5.0. The ferric iron is complexed with carbonate, bicarbonate or both to form a water-soluble complex that is anionic in nature and highly soluble in the alkaline aqueous ferric iron salt solution at pH above 8.5, and a pH of the alkaline aqueous ferric iron salt solution is at least 8.5.

An alkaline aqueous ferric iron salt solution is disclosed. Generally, the alkaline aqueous ferric iron salt solution comprises ferric ions (Fe.sup.3+), potassium ions (K.sup.+), carbonate ions (CO.sub.3.sup.2−), bicarbonate ions (HCO.sub.3.sup.−), hydroxide ions (OH.sup.−), optionally nitrate ions (NO.sub.3.sup.−). Further, a molar ratio of the potassium ions to the ferric ions is generally at least 5.0. The ferric iron is complexed with carbonate, bicarbonate or both to form a water-soluble complex that is anionic in nature and highly soluble in the alkaline aqueous ferric iron salt solution at pH above 8.5, and a pH of the alkaline aqueous ferric iron salt solution is at least 8.5.