A recycling process for achieving near-zero emissions of tannery effluent is characterized in that effluent recycling is carried out independently in soaking, liming, re-liming, de-liming bating, pickling chrome tanning, re-tanning, neutralizing, and dyeing procedures. The effluents in the above procedures can be recycled in each step. This process greatly reduces effluent discharge and helps solve the problem of tanning pollution. The process also improves the quality of the finished leather, effectively decreases loose grain rate and increases compactness and fullness of the finished product. The project can reduce chemical material consumption by 15%-55%. For example, the consumption of chromium powder can be reduced up to 65%. Consumption of other chemical materials can be reduced by more than 90%, while certain chemical materials can be essentially completely conserved.

A process for leather production from a raw animal hide includes the steps of pre-soaking, soaking, unhairing and liming, re-liming, deliming and bating, pickling and tanning, degreasing, re-tanning, neutralizing, dyeing and fatliquoring, and washing the processed hide. Waste liquid is collected from at least one of the foregoing steps is recycled to at least one of the foregoing steps. The collected waste liquid can be recycled to the same step, to a different step, or to two of more steps in the process.

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.

Described is a process of extracting metals from a wet mass which comprises: a step A of concentrating the metals in a carbonaceous solid by means of a thermochemical treatment of the wet mass, with the ancillary production of a treatment gas; a step B of thermochemical decomposition of the carbonaceous solid in an atmosphere constituted by an operating gas which contains oxygen in substoichiometric quantity to carry out the thermochemical decomposition in order to promote a combination of the metals with substances present in the carbonaceous solid to form salts and others solid compounds and to concentrate the latter in residual ashes of the carbonaceous solid at the same time providing for the formation of a combustible synthesis gas comprising hydrocarbons from the carbonaceous solid; a step C of extraction of the metals from the ashes produced.

A method for chromium removal from post-tanning wastewater includes the following steps: (a) mixing pretreated post-tanning wastewater with an induction reagent to allow an induction reaction; and (b) adjusting a pH of a mixture obtained after the induction reaction to higher than 7.0 for precipitation; where the induction reagent includes a soluble metal salt. In the treatment method of the present disclosure, pretreated post-tanning wastewater is mixed with an induction reagent, a small amount of neutral chromium complexes remaining in the wastewater are converted into cationic chromium complexes under the action of the induction reagent (that is, a charge property of the chromium complex is changed), and then a pH is adjusted for precipitation to remove chromium, which greatly improves the removal efficiency of chromium in wastewater.

Provided herein are compositions and methods useful for the treatment of wastewater comprising colloidal impurities. In certain aspects and embodiments, the compositions and methods include a natural deep eutectic solvent (NADES) coagulant including a hydrogen bond acceptor and a hydrogen bond donor, wherein the NADES is a liquid at room temperature.

A recycling process for achieving near-zero emissions of tannery effluent is characterized in that effluent recycling is carried out independently in soaking, liming, re-liming, de-liming bating, pickling chrome tanning, re-tanning, neutralizing, and dyeing procedures. The effluents in the above procedures can be recycled in each step. This process greatly reduces effluent discharge and helps solve the problem of tanning pollution. The process also improves the quality of the finished leather, effectively decreases loose grain rate and increases compactness and fullness of the finished product. The project can reduce chemical material consumption by 15%-55%. For example, the consumption of chromium powder can be reduced up to 65%. Consumption of other chemical materials can be reduced by more than 90%, while certain chemical materials can be essentially completely conserved.

Embodiments described herein generally relate to humidification-dehumidification desalination systems, including apparatuses that include a vessel comprising a humidification region (e.g., a bubble column humidification region) and a dehumidification region (e.g., a bubble column dehumidification region), mobile humidification-dehumidification (HDH) desalination systems (e.g., systems having a relatively low height and/or a relatively small footprint), and associated systems and methods. Certain embodiments generally relate to methods of operating, controlling, and/or cleaning desalination systems comprising a plurality of desalination units (e.g., HDH desalination units).

A method of treating a substrate with a solid particulate material and a treatment liquor comprising: agitating the substrate with said solid particulate material and said treatment liquor; and (a) separating the substrate from effluent comprising solid waste fragments derived from the substrate, said solid particulate material and the treatment liquor; (b) transferring said effluent to a hydrocyclone separator comprising an inlet, a first outlet and a second outlet, wherein the effluent is fed into the hydrocyclone separator via the inlet; (c) separating the effluent in the hydrocyclone separator to produce a first stream and a second stream, wherein the first stream comprises said solid particulate material and exits the hydrocyclone separator via the first outlet and wherein the second stream comprises treatment liquor and solid waste fragments and exits the hydrocyclone separator via the second outlet; and (d) collecting the first stream after it exits the hydrocyclone separator via the first outlet.

The present invention is directed at COD removal mixture comprising a) at least one inorganic coagulant; b) activated carbon, c) at least one organic coagulant; and d) optionally water wherein the mixture is a powder and a method of clarifying industrial waste water using the COD removal mixture.