TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The granules of electron donor material are elemental sulfur and comprise several sulfur pellets, sulfur nuggets, sulfur blocks and sulfur particles. The pellets, nuggets, blocks or particles have a size of 0.15-10 mm and the pieces of calcium carbonate material comprise oyster shell pieces. A total volume filled by the elemental sulfur in the bioreactor is approximately 3 times greater than a total volume filled by the oyster shell pieces, and the bioreactor interior cavity is greater than 10 liters. The pieces of calcium carbonate material are crushed shells of oysters, clams, snails, or other mollusks, and/or crushed coral. The electron donor is elemental sulfur and at least one of the bacteria species is a member of the beta-proteobacteria or alpha-proteobacteria. The granules of electron donor material have a size of 0.15-10 mm and the pieces of calcium carbonate material have a size of 0.25-10 mm. The granules are sulfur and the pieces are mollusk shell and an average size of the mollusk shell pieces is larger than an average size of the sulfur granules. The sulfur granules have a size of 0.3 mm and the oyster shell pieces have size of 0.60 mm. The sulfur granules and the oyster shell pieces are in the range of 0.3-5 (preferably 0.4-2) mm and 0.6-8 (preferably 0.85-5) mm. In the system, the buffering material maintains an alkalinity of greater than 30 mg/l as equivalent CaCO3 in the bioreactor. The buffering material has calcium carbonate content of greater than 90 wt.% substantially in the form of aragonite and the weight % of carbon (C), calcium (Ca) and magnesium (Mg) are present in such a ratio that the ratio of Mg:Ca is less than 50% or Ca:C is greater than 75%, or both of Mg:Ca is less than 50% and Ca:C is greater than 75%.    TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred System: The bioreactor further includes a bioreactor portion, a bioreactor cavity having a volume of at least 10 liters in the bioreactor portion, at least one opening in the bioreactor cavity, at least one bioreactor inlet pipe sealably connected to an opening in the bioreactor cavity, and at least one bioreactor outlet pipe sealably connected to an opening in the bioreactor cavity. The system further comprises an optional post-treatment system including a post-treatment tank having a post-treatment tank portion, a post-treatment tank interior cavity, at least two openings in the post-treatment tank portion, at least one post-treatment inlet pipe having an inlet end and an outflow end, and at least one post-treatment outlet pipe having an inlet end and an outflow end. The inflow end of the post-treatment outlet pipe is connected to an opening of the post-treatment tank body. The outflow end of a post-treatment tank inflow pipe is connected to at least a second opening in the post-treatment tank body. The inflow end of the post-treatment tank inflow pipe is sealably connected to at least one bioreactor outlet pipe or to an opening in the bioreactor body portion. The system is configured to allow a liquid to pass into the bioreactor. The media is arranged such that the liquid can enter the bioreactor cavity through the at least one pipe and contact the media, and after the contact the liquid exits the bioreactor cavity through the post-treatment tank inflow pipe. The liquid passes through the post-treatment inlet pipe into the post-treatment tank interior cavity and subsequently exhausts through the post-treatment tank outlet pipe. The system further comprises at least one flow regulator each connectedly operable with at least one of an opening, an inlet pipe, and an outlet pipe. The bioreactor further comprises several living micro-organisms, including at least one of a species of perchlorate reducing bacteria that live on the granules of electron donor material and respire on perchlorate. The system further comprises at least one pumps and each flow regulator is connectedly operable with at least one of a pump, an opening, an inlet pipe, and an outlet pipe. The system further comprises at least one sampling port; at least one flow sensor; at least one sampling sensor; an automated flow-regulation controller; a computer; an electronic control interface; a backwash system comprising a first backwash opening in the body portion sealably connected to a backwash inlet pipe, a second backwash opening in the body portion sealably connected to a backwash outlet pipe, a source of backwash water, a backwash pump; and a backwash flow regulator. The flow-regulator controller is mechanically or electrically connected controllably to the flow regulator. The computer is electrically and controllably connected at least to the flow-regulator controller; and the electronic control interface is operably connected to the computer and to at least one of a sensor, pump, flow regulator, and flow-regulator controller. The bioreactor is a perchlorate-reduction bioreactor. The post-treatment system includes a biocell-reduction sand filter and the perchlorate-reduction bioreactor is located upstream of the post-treatment system. In the system, the media comprises the electron donor and the buffering material and the media is positioned in a cavity of the bioreactor. The electron donor is in fluid communication with the buffering material. The buffering material provides alkalinity at a rate of \)8 equivalents of mg/l CaCO3 per day or at a rate of not greater than 1.25 milliequivalents per hour per gram of buffer material. The system also comprises an entry passage for delivery of a perchlorate-containing liquid into the bioreactor cavity such that the liquid contacts the media; and the exit passage. Alternatively the system comprises a system influent pipe and a system effluent pipe; at least one ion exchange reactor; the perchlorate-reduction bioreactor; a brine source; and at least one valve or fluid connector arranged to switchably connect the pipes, the brine source, the bioreactor and at least a first ion exchange reactor between alternative configurations such that in a first configuration water can pass from the system influent pipe through the ion exchange resin within at least a first ion exchange reactor and exit from the system via the outlet opening of the at least first ion exchange reactor and the system effluent pipe; in a second configuration a brine can pass from the brine source through the at least a first ion exchange reactor and through the resin within the reactor volume; and in a third configuration the brine can pass through the bioreactor. Each ion exchange reactor has an internal volume, a perchlorate-reduction ion exchange resin disposed within the internal volume, inlet and outlet openings such that influent water can enter the inlet opening, contact the resin and exit the reactor via the outlet opening. The bioreactor has inlet and outlet openings. Preferred Method: The method (M1) further involves after the step of passing the treated liquid out of the bioreactor outlet opening, post-treating the treated liquid by substantially filtering biocells with a sand filter. When the liquid is water, the method of treatment of water from the water source involves supplying inlet water from the water source such that the water has a first perchlorate concentration; providing an optional pretreatment system having at least one inlet and at least one outlet; providing the bioreactor; connecting the outlet of the optional pretreatment system to the inlet of the bioreactor, providing media comprising sulfur granules and mollusk shell pieces and disposing the media in the bioreactor interior cavity in such manner that water passing through the bioreactor cavity will make fluid contact with the media, and seeding the media with a sludge containing bacteria, configuring the optional pretreatment system, bioreactor, and each of the inlet and outlet opening to enable water to pass through the pretreatment system into the bioreactor cavity in such manner that the water will make fluid contact with the media and subsequently exit from the bioreactor, and optionally passing the water having a first perchlorate concentration from the water source into the pretreatment system to form pretreated water having a perchlorate concentration, passing the optionally pretreated water having a perchlorate concentration into the bioreactor to come into fluid contact with the media and forming treated water having a second perchlorate concentration less than the first concentration, and passing the treated water out of the bioreactor outlet opening as outlet water. The step of passing water having a first perchlorate concentration into the optional pretreatment system to form pretreated water involves substantially removing at least one of particulate matter or litter material from the inlet water. The method further involves supplying inlet water from a catchment, a holding tank, an industrial wastewater stream or other waste water source, providing the media in the bioreactor such that sulfur granules comprise pellets, nuggets, blocks and particles of elemental sulfur not greater than 2 mm in diameter and the volume ratio of sulfur granules to mollusk shell pieces in the bioreactor is 250-350%, seeding the media with sludge containing several living micro-organisms comprising species of perchlorate-reducing bacteria that grows on sulfur and respires on perchlorate, moving the water within the bioreactor in a direction of primary flow during treatment at a flow rate greater than 0.2 l/hour, receiving the treated water from the bioreactor into at least one outlet pipe to create outlet water, and improving the quality of the outlet water relative to the quality of pretreated water. The step of seeding the media with sludge includes seeding with sludge containing at least one member of the beta- or alpha-proteobacteria. The method further involves providing a recycling pump and recycling pipe between the bioreactor outlet opening and the bioreactor inlet, optionally recirculating the water in the bioreactor system at a recirculation flow rate, which is the lesser of 9.7 cm/min or 52 times the influent flow rate; providing a backwash system comprising a backwash inlet pipe entering the bioreactor interior cavity, a backwash outlet pipe exiting the bioreactor interior cavity and a backwash pump; providing the source of backwash water; introducing backwash water to the backwash inlet pipe; activating the backwash pump to pump the backwash water through the media; backwashing at a pressure of 60-180 (preferably 80-100) PSI; receiving backwash water that has passed through the media, and releasing backwash water from the bioreactor through the backwash outlet pipe. The method of treating the water further involves improving the quality of the outlet water relative to the quality of the inlet water by producing outlet water that has substantially lower concentration of perchlorate and that of relative to the quality of pretreated water by producing outlet water that has substantially lower concentration of perchlorate. The method further involves producing outlet water that has, on average, a perchlorate concentration of less than 10% of the perchlorate concentration of the inlet water. The treatment method of water further involves providing a media buffering material in which water placed in fluid contact with the media buffering material, upon addition of an acid titrant of 2.5 milliequivalents per liter of H+ ions sufficient to shift the pH of the water from a starting pH value Y to a new pH of 3, will recover 68% of its starting pH value i.e. 68%xY within 140 minutes. The method (M1) further involves periodically activating the backwash pump to pump the backwash water through the media in a direction opposite to the direction of primary flow during treatment. The outlet water has on average a perchlorate concentration of less than 0.5 mg/l. The step of passing the optionally pretreated water into the bioreactor to come into fluid contact with the media and to form the treated water further involves delivering the optionally pretreated water in which aeration is substantially absent inside the bioreactor and the fluid contact between the liquid and the media is substantially anoxic. The bacteria colonize both upon the sulfur granules and upon the mollusk shell pieces. The water contacts the media for 8-40 hours. The method further involves prior to the step of providing a media, providing mollusk shell pieces and sterilizing the crushed, unmodified mollusk shells prior to providing the media. The oyster shell pieces are used to control alkalinity. The step of providing a media further involves providing a media comprising crushed, unmodified oyster shells obtained through a source that is a commercial source of crushed oyster for poultry farming or is a source of industrial bi-product oyster shells from the oyster industry. In the method (M1), the bioreactor is a perchlorate reduction bioreactor and the buffer material is unmodified oyster shell pieces. The backwashing is conducted not more than once every six months. The method (M1) further involves producing outlet water that has, on average, a perchlorate concentration of less than 2% of the perchlorate concentration of the inlet water and further involves maintaining the produced outlet water at less than 2% concentration of the perchlorate concentration of the inlet water after at least 100 days of operation. A flow in the bioreactor is recirculated at a 9.7 cm/minute recirculation velocity and an empty bed contact time is less than 40 hours. The method (M1) further involves maintaining the produced outlet water at less than 10% concentration of perchlorate in the inlet water after at least 260 days of operation without recirculation and with an empty bed contact time less than 15 hours. The method (M2) further involves providing the granules of electron donor material in which pellets, nuggets, blocks or particles are in the range of 0.15-10 mm, and providing pieces of calcium carbonate material comprising oyster shell pieces such that a total volume in the bioreactor filled by the elemental sulfur is approximately three times greater than a total volume filled by the oyster shell pieces. In the method (M2), the step of seeding the media with a sludge containing sulfur-utilizing, perchlorate reducing bacteria involves seeding with a sludge containing at least one of a bacteria species that is a member of the beta- or alpha-proteobacteria. In the method (M2), the pieces of calcium carbonate material have at least 90 wt.% of calcium carbonate in the form of aragonite. The step of providing media further involves providing calcium carbonate material having at least 90 wt.% of calcium carbonate in the form of aragonite. EXAMPLE - None given.