**5. Guidelines for reuse of human and animal waste products as organic fertilizers**

The WHO operational monitoring guidelines for the reuse of wastewater, excreta and greywater to fertilize crop strictly advocate certain validation requirements, operation monitoring parameter and technical measures, and verification monitoring are as stated in **Table 7** for safe reuse of waste. WHO guidelines [48] exemplify the die-off efficiency with a temperature of 50°C for at least 1 week before compost or ecohumus is considered safe for reuse. If this temperature is not achieved, a longer composting/storage time has been advo‐ cated by WHO. One to two years of storage is recommended for systems that generate ecohumus for proper removal of bacterial pathogens and appreciable reduction of viral and parasitic protozoa. WHO [48] identified the risk on the exposed groups to the reuse of the excreta and wastewater, and recommended health protective measures. The guidelines also include standards for chemical in fish and vegetables. According to the guideline, ≤1 hel‐ minth's eggs (arithmetic mean number) per litre or per gram total solid applies for excreta to be used on edible products and organic fertilizers to which agriculture workers would be exposed. The guidelines also contain threshold values for bacterial pathogens (based on ≤ 104 – ≤ 10<sup>5</sup> CFU *E. coli* per 100 mL or g total solid) and for trematode eggs (absent) in aquaculture.


**Table 7.** Validation requirements, operation mornitoring parameter and technical measures, and verification monitoring for reuse in fertilization (adapted from WHO [48]).
