Firstly; biting at that age is completely normal. They have begun to feel some real emotions like anger, jealousy, etc as opposed to basic needs like hunger and tiredness. But without the verbal tools to express these feelings, they use inappropriate ways like biting, pushing and hitting.
Having said that... biting may be normal, but it is NOT okay. I always say that, with any kind of aggressive behaviour, the shadow technique seems to work the best. This involves keeping the child immediately beside you for (sigh) every single moment of the day. You don't "entertain" them, you just stay within an arms reach. Yes, this means taking them to the bathroom with you if they are not napping or contained otherwise. The instant he begins to bite/hit, etc you grab his hand or move him away and say "NO. We do not bite. Biting HURTS." You're not using a mean voice, but soft and fuzzy won't work here, either. The idea is to both prevent the incident, and also communicate that it cannot happen. It can be very tiring, but after a full day or two, you begin to allow them to interact alone again. If something happens again, you institute an IMMEDIATE consequence (I certainly use a time out in the case of aggressive behaviour).
This should improve things fairly quickly. And if they don't get better, I would unfortunately say goodbye. I cannot jeopardize the other children for any longer than necessary.
I hope it gets better soon!