TY JOUR TI SIMULATION OF THE WASTE WATER PURIFICATION SYSTEM OF LIVESTOCK FARMS BASED ON PETRI NETS KW modified Petri nets KW wastewater treatment of livestock farms KW simulated systems KW chemical and technological system KW computer modeling JO Agrobiotechnologies and digital farming AU Savdur, S.N. PY 2023 IS 2 PB Kazan state agrarian University