organic matter that appear in the sludge of waste water 

Biohazardous waste, including medical, pharmaceutical, veterinary, farming and slaughterhouse waste which contain virulent pathogenic microorganisms with potential infectious disease causing impact...

No prevent the spreading of toxic components or leaching into soils and groundwater. 

http://siteresources.worldbank.org/INTSERBIA/Resources/SerbiaEnvironmentOct2007.pdf

They are various  and sometimes specific to specific sites.  Most of the times with a good scientific background and techniques these can be easily eliminated too.

Improperly treated municipal sewage.  There has to be proper liquid effluent  and solid waste (especially domestic) treatment management which is capable of reducing the pathogens in municipal waste water.

Identification of Wastewater Organisms

http://www.norweco.com/html/lab/identify.htm

Wastewater bacteria book by Michael H. Gerardi

http://files.instrument.com.cn/FilesCenter/20080727/2008727148773959.pdf

Common Contaminants in Wastewater

http://www.sheffy6marketing.com/index.php?page=common-contaminants-in-wastewater

Main scources are human beings who are ill, esp. bacteria and viruses.

It is to be noted that hospitals, research lab,, meat/fish shops etc. are mostly located in the cities. There is no gainsaying to the fact that the effluents form such activities find their way into the sewers. This is why the municipal wastewater may contain pathogens .

Just about any enteric source that derives waste from host biomass; pathogens are usually found in water borne faecal waste. 

The sources that deliver pathogens could be drains from hospitals, slaughter houses, hotels, research labs and human wastes as well.

The most common pathogenic indicator is the faecal coliforms associated with contamination by human excreta. Therefore, in Municipal wastewater, the common sources are residential and commercial centers connected to the municipal sewer.

Hospitals, pathological analysis laboratories, medical and biological research centers.

Any contaminated resource which is present in the ecosystem.

Dear Rana Kadhim Mohammed , your link is not working!

Sorry Dr. Ljubmir..... please follow the link:

http://www.clw.csiro.au/publications/technical97/tr1-97.pdf

Dear Rana Kadhim Mohammed , this is excellent resource, no matter the date of project -1997. Thanks.

Yes prof. Ljubomir.. It's not Due date. But it's excellent Resources. Amiable greetings

Hospital waste

Article Removal of pathogenic bacteria from sewage‑treated effluent ...

Hospitals, pathological analysis laboratories, medical and biological research centers.

https://www.researchgate.net/publication/237002112_Pseudomonas_aeruginosa_burn_wound_infection_in_a_dedicated_paediatric_burns_unit

Fecal matter is a major component of domestic sewage and the source of the majority of human pathogens in wastewater. Industrial waste from food production, particularly from animal processing, can also be a source of pathogenic microorganisms.