export function translateHttpLoaderFactory(httpBackend: HttpBackend): TranslateHttpLoader {
    return new TranslateHttpLoader(new HttpClient(httpBackend));
}

...
        TranslateModule.forRoot({
            loader: {
                provide: TranslateLoader,
                deps: [HttpBackend],
                useFactory: translateHttpLoaderFactory
            }
        }),

import {Inject, Injectable} from '@angular/core';
import {HttpEvent, HttpHandler, HttpInterceptor, HttpRequest} from '@angular/common/http';
import {Observable} from 'rxjs';

import {API_BASE_URL_TOKEN} from '../../shared/config.module';

@Injectable()
export class ApiBaseUrlInterceptor implements HttpInterceptor {
    private readonly apiBaseUrl: string;

    constructor(@Inject(API_BASE_URL_TOKEN) apiBaseUrl: string) {
        this.apiBaseUrl = apiBaseUrl;
    }

    public intercept(request: HttpRequest<any>,
                     next: HttpHandler): Observable<HttpEvent<any>> {
        return next.handle(request.clone({url: `${this.apiBaseUrl}${request.url}`}));
    }
}