# **Box  5.1 Sample strategy and action plan for incremental application of WHO guidelines**

> **_Pathogen reduction targets:_** Phase in pathogen reduction targets over suitable period of time (e.g., 15−20 years) according to treatment capabilities and other feasible barriers. For example, for a large irrigation scheme in a low-income country, and assuming that the 2006 WHO risk assessment and management framework has been applied as shown in Annex A, interim log unit pathogen reduction targets could be set as follows for the reference pathogens norovirus and _Ascaris_ :

||**Implementation Phase:**|**Phase I**|**Phase II**|**Phase III**|
|---|---|---|---|---|
||**DALY loss pppy:**|**1 × 10**<sup>**−4**</sup>|**1 × 10**<sup>**−5**</sup>|**1 × 10**<sup>**−6**</sup>|
|Norovirus:|Restricted irrigation|1 log unit|2 log units|3 log units|
||Unrestricted irrigation|4 log units|5 log units|6 log units|
|_Ascaris_eggs:|Restricted irrigation|1 log unit|2 log units|3 log units|
||Unrestricted irrigation|3 log units|3 log units|4 log units|

**_Treatment:_** Introduce or upgrade treatment at strategic locations where wastewater irrigation is taking place or could be encouraged, phased in over the plan time period. For example, treatment options to be considered could include:

_First stage of treatment:_ natural purification processes (e.g., abstraction suitable distance downstream from discharge); irrigation storage ponds or reservoirs designed for pathogen removal, waste stabilization ponds, upflow anaerobic sludge blanket reactors, primary treatment plus additional treatment (e.g., storage reservoir, chemically enhanced coagulation, coagulation + rapid sand filtration).

_Second stage of treatment:_ waste stabilization ponds, wastewater treatment and storage reservoirs, conventional secondary treatment (e.g. activated sludge, trickling filter, etc.), aeration ponds, etc.

_Third stage of treatment:_ waste stabilization ponds, conventional secondary treatment + storage reservoirs or disinfection, advanced tertiary processes (e.g., membrane filtration, disinfection), soil aquifer treatment system.

**_Strengthen local capacity:_** Assemble a team of health and agricultural outreach workers who can work with farmers and villagers to improve health and agricultural practices and develop feasible crop restriction strategies and other interventions as necessary.

> **_Health and hygiene education:_** Expand existing hygiene and sanitation outreach programs to include information on potential health effects of wastewater use; educate farmers, produce vendors and consumers about food safety and hygiene.

> **_Crop restriction:_** Work with farmers to develop feasible and health protective crop restrictions, especially in the areas of highest risk (e.g., where undiluted raw wastewater is used).

**_Wastewater application_** _:_ Determine the safety level of current practices. As resources/technologies permit, shift over time to safer wastewater/excreta application practices where there is less human contact (e.g., drip and bubbler irrigation).

**_Human exposure control:_** Expand hygiene and health education programs in affected communities. Require protective clothing at larger wastewater/excreta use projects and where feasible. Provide clean water at markets for ‘freshening produce.’ Inspect general hygiene at food markets.

**_Other health interventions:_** Initiate or expand vaccination campaigns in affected areas (e.g. typhoid, hepatitis A). Complement hygiene and sanitation programs with periodic antihelminthic drug campaigns; this works well

51