37 Construction of water, wastewater and waste treatment facilities with municipal water, industrial water, wastewater, agricultural and food processing waste, solid waste and food waste, waste sludge from industrial processes, and waste sludge from municipal water, industrial water and wastewater treatment systems, namely, anaerobic digestion systems, water filtration systems, biogas production, biogas storing and processing systems and fertilizer production systems; construction of equipment and facilities in the field of municipal water, industrial water, wastewater, agricultural and food processing waste, solid waste and food waste, waste sludge from industrial processes, and waste sludge from municipal water, industrial water and wastewater treatment, anaerobic digestion systems, water filtration, biogas production, biogas storing and processing and fertilizer production; construction of biomethane upgrading systems comprised of gas purification machines; construction of biogas conditioning equipment, namely, gas-permeable membrane separators for the cleaning and purification of liquid, gas and air used for renewable natural gas production, industrial scrubbers for removing particulate matter from the air during industrial processing, namely, venturi scrubbers, impingement scrubbers, dynamic scrubbers; construction of systems in the field of processing solid waste and food waste to recover materials for thermal processing and organics and recyclables; construction of systems to produce suitable feedstock for anaerobic digestion