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Updated Effluent / Waste Water Quality Standards

Written by Janice M on . Posted in Water & Environmental

Regulations or guidelines for effluent / waste water quality (National Water Act 36/1998) have been updated and changed in the South African Government Gazette No. 36820, 6 Sept. 2013.

This article will discuss the importance of these guidelines, what the limits are and how you can monitor water quality in your environment.

 

 

1. Why should your Business care about the Quality of Industrial Water you release into the environment?

  • Water scarcity and degradation is increasing along with the world’s population. (Quick fact: Water use has been growing at more more than twice the rate of the population increase in the last century). Each business needs to try and conserve this precious resource in order to control pollution and protect our ecosystems

  • Monitoring the quality of your wastewater and taking corrective action where necessary protects the health and safety of the people and environment in your vicinity

  • The law requires Water Users (this includes farmers, small-holders, communities, companies and businesses, water user associations, water service providers) to register with the responsible authority and release clean water into the environment. Water that has been used (waste / effluent water) must comply with special wastewater limit values before release into a water resource. Registration forms are available on the DWA website. Use the Registration Guide for advice on registering

  • Water discharge is monitored by local governing bodies such as municipalities and Water Users that do not comply with the waste water limits can be charged a penalty fee

2. How to Start a Waste Water Monitoring Programme:

  • Firstly, the amount of water that flows through a wastewater system needs to be measured with a Flow Meter, in order to calculate the amount of water flowing through

  • Water users can start monitoring the basic requirements of Water Quality (see table below) and progress to adding more substances / tests to their monitoring schedule

  • The most common, modern method municipalities use to test physical and chemical substances in water is Photometric, using a modern electronic instrument known as a photometer. These have step-by-step instructions and can be performed by a layman. Many photometers can test for between 3 and 70 different substances. It is a good idea to purchase a photometer that has additional parameters, so your requirements can be met once the water programme develops. Should you wish to do additional tests, you can then purchase the chemical reagents where needed.

  • Photometers are available in hand-held, bench-top and in-line versions. Larger district municipalities often have an in-house water testing laboratory with a bench-top photometer / spectrophotometer. Smaller hand-held photometers are often used in the field and in rural areas. However, many municipalities still use the long-standing visual Lovibond® comparator system. Should you use a comparator (colorimeter) or a photometer for measuring water quality?

  • Faecal contamination is also a vital substance to measure in wastewater. E.coli bacteria are the common microbiological parameter measured. A quick test to reveal the presence / absence of bacteria in water can be performed using an ATP luminometer. More detailed investigations will require a test kit and incubation for 12 – 48 hours

  • Some municipalities perform some of these basic tests themselves on a regular basis and contract out the less frequent testing to a Water Laboratory for analysis. Doing the analysis oneself  ensures a faster response time. According to the  Lovibond® Tintometer® White Paper – In-House Water Sampling contributes to huge savings in Today’s Industry

  • Records of the Water Monitoring Programme and corrective action taken need to be kept

  • Corrective action plans need to be set up and put in motion by the addition of water treatment chemicals, so that clean water can be released back into the environment
lovibond-md600-photometer

The digital Lovibond® MD600 can monitor up to 70 different substances in water

3. What substances (Parameters) should you check?

3.1 Monitoring Smaller quantities* of Waste Water Discharge:

DISCHARGE VOLUME ON ANY GIVEN DAY
MINIMUM MONITORING REQUIREMENTS
10 to 100 cubic metres pH
Electrical Conductivity (mS/m)
Faecal coliforms (per 100 ml)
100 to 1 000 cubic metres pH
Electrical Conductivity (mS/m)
Faecal coliforms (per 100 ml)
Chemical Oxygen Demand (mg /l)
Ammonia as Nitrogen (mg/l)
Suspended Solids (mg/l)
1 000 to 2 000 cubic metres pH
Electrical Conductivity (mS/m)
Faecal coliforms (per 100 ml)
Chemical Oxygen Demand (mg /l)
Ammonia as Nitrogen (mg/l)
Nitrate / Nitrite as Nitrogen (mg/l)
Free Chlorine (mg/l)
Suspended Solids (mg/l)
Ortho-Phosphate as Phosphorus (mg/l)

* Specifications for a wastewater treatment works discharging < 2 000 cubic metres (2 megalitres) / day
Source – Government notice 399 of 26 March 2004.

3.2 What is the difference between General waste water limits and Special waste water limits?

  • GENERAL WASTE WATER LIMITS: You may discharge up to 2 000 cubic metres of wastewater on any given day into a water resource that is NOT a listed water resource set out in the table: Table: Listed water resources (water to areas other than rivers and dams). Here you need to comply with General waste water limits

  • SPECIAL WASTE WATER LIMITS:You may discharge up to 2 000 cubic metres of wastewater on any given day into a listed water resource set out in the Listed water resources (mainly rivers and dams). Here you comply with the Special waste water limits. These limits are stricter because of sensitivities of some catchment areas
NOTE: These discharge limits exclude complex industrial wastewater.

Waste water Limits applicable to discharge of waste water into a water resource:

SUBSTANCE / PARAMETER
GENERAL LIMIT
SPECIAL LIMIT
Faecal Coliforms (per 100 ml) 1 000 0
Chemical Oxygen Demand (mg/l) 75* 30*
pH 5.5 – 9.5 5.5 – 7.5
Ammonia (ionised and un-ionised) as Nitrogen (mg/l) 6 2
Nitrate / Nitrite as Nitrogen (mg/l) 15 1.5
Chlorine as Free Chlorine (mg/l) 0.25 0
Suspended Solids (mg/l) 25 10
Electrical Conductivity (mS/m) 70 mS/m above intake to a maximum of 150 mS/m 50 mS/m above background receiving water, to a maximum of 100 mS/m
Ortho-Phosphate as phosphorus (mg/l) 10 1 (median) and 2.5 (maximum)
Fluoride (mg/l) 1 1
Soap, oil or grease (mg/l) 2.5 0
Determinants applicable to Certain Industries & Mines:
Dissolved Arsenic (mg/l) 0.02 0.01
Dissolved Cadmium (mg/l) 0.005 0.001
Dissolved Chromium (VI) (mg/l) 0.05 0.02
Dissolved Copper (mg/l) 0.01 0.002
Dissolved Cyanide (mg/l) 0.02 0.01
Dissolved Iron (mg/l) 0.3 0.3
Dissolved Lead (mg/l) 0.01 0.006
Dissolved Manganese (mg/l) 0.1 0.1
Mercury and its compounds (mg/l) 0.005 0.001
Dissolved Selenium (mg/l) 0.02 0.02
Dissolved Zinc (mg/l) 0.1 0.04
Boron (mg/l) 1 0.5
*After removal of algae Source: Table 2.1 South African Government Gazette No. 36820, 6 Sept. 2013

3.3 How often should the quality of industrial waste water be monitored?

According to Government Gazette No. 36820:
  • The quantity of the discharge must be metered and the total recorded weekly;
  • The quality of industrial waste water discharges must be monitored once every month by grab sampling
  • Monitoring for the quantity and the quality of the discharge shall be done at the point of discharge into a water resource and results submitted to the responsible authority
More detail

Water Reuse in Practice

Wateronline.com has an interesting feature entitled “Industrial Case Study: Lessons From Nestlé’s Zero Water Facility”.(see page 44 – 46.)

The article describes how a milk factory in Mexico implemented zero water technology. The aim of zero water technology is to extract water from the materials it manufactures and and to reuse it for industrial processes. Nestlé describes how they began the project and how they found that reuse was their best chance of achieving zero water. Opportunities they discovered and obstacles are discussed in a practical way.

Read more

Water Quality Guidelines for the South African Coastal Zone

A most important indicator of water quality in coastal zones are Faecal Coliforms and E.coli. Stormwater and marine disposal pipelines drain into the sea and this microbiological indicator of water quality needs to be monitored and managed for the safety of users.

Heavy metals and other pollutants also get washed into coastal areas and can affect the marine ecosystem.

Download Water Quality Guidelines for the South African Coastal Zone

Useful sites for further reading:

June 2018 – links updated.

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