I have the Global.asax like the code below:

public class MvcApplication : System.Web.HttpApplication
{
    public static void RegisterRoutes(RouteCollection routes)
    {
    // ....
    }

    protected void Application_Start()
    {
    AreaRegistration.RegisterAllAreas();

    RegisterRoutes(RouteTable.Routes);

    ControllerBuilder.Current.SetControllerFactory(typeof(IOCControllerFactory));
    }
}

public class IOCControllerFactory : DefaultControllerFactory
{
    private readonly IKernel kernel;

    public IOCControllerFactory()
    {
        kernel = new StandardKernel(new NanocrmContainer());
    }

    protected override IController GetControllerInstance(RequestContext requestContext, Type controllerType)
    {
        if (controllerType == null)
            return base.GetControllerInstance(requestContext, controllerType);

        var controller = kernel.TryGet(controllerType) as IController;

        if (controller == null)
            return base.GetControllerInstance(requestContext, controllerType);

        var standartController = controller as Controller;

        if (standartController is IIoCController)
            ((IIoCController)standartController).SetIoc(kernel);

        return standartController;
    }

    class NanocrmContainer : Ninject.Modules.NinjectModule
    {
        public override void Load()
        {
            // ...

            Bind<DomainModel.Entities.db>().ToSelf().InRequestScope().WithConstructorArgument("connection", "Data Source=lims;Initial Catalog=nanocrm;Persist Security Info=True;User ID=***;Password=***");
        }
    }
}

In this case if somewhere it is the class, defined like:

public class UserRepository : IUserRepository
{
    private db dataContext;
    private IUserGroupRepository userGroupRepository;

    public UserRepository(db dataContext, IUserGroupRepository userGroupRepository)
    {
        this.dataContext = dataContext;
        this.userGroupRepository = userGroupRepository;
    }
}

then the dataContext instance is created (if no one was created in this request scope) by Ninject.

So the trouble now is - where to invoke dataContext method .Dispose()?