PIA GmbH - Greywater plants

Greywater plants already have a high level of technical maturity and reliability. In addition to further technical optimisation, however, it is crucial to inform relevant customer groups in order to successfully market such plants.

An international comparison of such plants does not result in a homogeneous requirement profile due to a variety of norms, standards and requirements. In Europe and the vast majority of nations, there are no specific legal regulations for greywater plants. Even the definition of greywater frequently differs as to whether more strongly loaded kitchen effluents should be taken into account and where recycled greywater can be used.

By testing according to existing regulations and orientating to national fact sheets and rules, one/the industry can create an appropriate means to ensure access to national domestic markets today and to demonstrate the quality of products to customers effectively.

Greywater plants are often combined with rainwater systems..

PIA offers the following different test methods:

NSF/ANSI 350

Extensive American test methods for domestic and commercial greywater plants with numerous end uses.

NSF/ANSI 350:: For domestic and commercial water reuse, sewage and greywater treatment plants.
NSF/ANSI 350-1:: For domestic and commercial water re-use greywater treatment systems for underground infiltration.

NSF/ANSI 350 test conditions and effluent criteria
Measure	Class R		Class C
Scope	≤ 5.678 L/d (1.500 gal/d)
Test duration	min. 26 weeks
Effluent Criteria	Test average	Single sample maximum	Test average	Single sample maximum
¹ Calculated as geometric mean ² If chlorine disinfection is used with a storage vessel ³ NA: Not applicable ⁴ MR: Measured and reported only
CBOD5 [mg/l]	10	25	10	25
TSS [mg/l]	10	30	10	30
turbidity [NTU]	5	10	2	5
E.coli1 [MPN/100ml]	14	240	2.2	200
pH [SU]	6,0 to 9,0	NA³	6,0 to 9,0	NA
Free available chlorine² [mg/l]	≥ 0.5 to ≤ 2.5	NA	≥ 0.5 to ≤ 2.5	NA
color	MR⁴	NA	MR	NA
odor	nonoffensive	NA	nonoffensive	NA
oily film and foam	nondetectable	NA	nondetectable	NA

BS 8525-1+2

British design and test method for domestic greywater plants and grey water reservoirs.

BS 8525 test conditions and effluent criteria
Measure	Spray application	Non-spray application
		WC flushing	Garden watering	Laundry
Scope	≤ 10.000 L/d
Test duration	10 test cycles
Effluent Criteria
¹ NA: Not applicable
turbidity [NTU]	< 10	< 10	NA	< 10
pH [SU]	5 to 9,5	5 to 9,5	5 to 9,5	5 to 9,5
Free available chlorine [mg/l]	< 2	< 2	< 0.5	< 2
E.coli1 [/100ml]	not detected	250	250	not detected
Intestinal enterococci	not detected	100	100	not detected
Residual bromine [mg/L]	0.0	< 5.0	0.0	< 5.0
Free available chlorine² [mg/l]	≥ 0.5 to ≤ 2.5	NA	≥ 0.5 to ≤ 2.5	NA
Legionella pneumophila [/100ml]	10	NA¹	NA	NA
Total coliform [/100ml]	10	1000	1000	10

AS 1546.4: 2016

DR AS 1546.4:2016 - On-site domestic wastewater treatment units - Part 4: Domestic greywater treatment systems

The Australian Standard 1546.4 will complements the series 1546 by a test method for domestic (on-site) grey water treatment plants that have a daily treatment capacity of up to 1000 l/day.

Product certification according to this standard is mandatory for access to the Australian market. It also enables treated greywater to be used in numerous areas (see table).

In contrast to the NSF/ANSI 350 and BS 8525 methods, the test is performed with greywater from a natural source.

The examination regularly lasts 27 to 35 weeks, plus a start-up phase of up to 8 weeks. Influent and effluent are sampled one to three times per week, depending on the test period.

For a Level 1 approval, an additional stress phase with pathogens (using a synthetic greywater with indicator organisms) of 9 days plus start-up phase is required.

The flow requirements are shown in simplified form in the following table:

	Level 1	Level 2	Level 3
	Effluent quality and associated end-uses
	(all Level 2) + Washing machine Hand-held hose (car washing/ garden watering)	(all Level 3) + Covered surface drip/spray irrigation Toilet/Urinal flushing	Shallow sub-surface drip irrigation
* where applicable
Parameter	(according to Standard Methods)
BOD₅ [mg/L]	90% ≤ 10 (Max. 20)	90% ≤ 10 (Max. 20)	90% ≤ 20 (Max. 30)
TSS [mg/L]	90% ≤ 10 (Max. 20)	90% ≤ 10 (Max. 20)	90% ≤ 30 (Max. 45)
Turbidity [NTU]	90% ≤ 2 (Max. 5)	90% ≤ 2 (Max. 5)	-
E. coli [cfu/100 mL]	90% ≤ 1 (Max. 10)	90% ≤ 10 (Max. 30)	90% ≤ 10 (Max. 30)
Residual FAC* [mg/L]	X ≥ 0,5	X ≥ 0,5	X ≥ 0,5
Microbiol. Challenge		-	-

PIA - Prüfinstitut für Abwassertechnik GmbH

Water Reuse

Greywater plants

NSF/ANSI 350

BS 8525-1+2

AS 1546.4: 2016

Effluent quality and associated end-uses

News

BMBF selects Aachen network for wastewater reuse

Publication of the standard DIN EN 16941-2:2021-11

Publication of the new European Standard for the use of Rainwater in June 2018

Veröffentlichung des australischen Grauwasser Standards AS 1546.4:2016 „On-site domestic wastewater treatment units – Domestic greywater treatment systems“