An Overview of the Current State and Prospects for Oil Recovery from Oily Sludge oleh Chinakulova Aigerim Nurlankyzy, Niyazbekova Rimma Kalmanbayevna, Khaldun Mohammad Al Azzam, Mukhambetov Gabit Mukhambetovich, Aimagambetova Raushan Zhanatovna, El-Sayed Negim, Serekpayeva Mira