Chapter 19: Liquid Effluent and Protection of Watershed and Aquatic Environment

Effective Date: July 1, 1997 (Issue No. 2)

Last Updated: September, 2024

A. Introduction

HKUST is committed to protect and uphold water quality in our surrounding environment to protect ecosystems, wildlife, and human health and welfare. Members of the university are required to strictly follow relevant policies and practices, including compliance to applicable laws regulating liquid effluents. In terms of preventing and reducing marine pollution of all kinds, in particular from land-based activities, the university has committed to achieving a high environmental standard (Platinum Level in Building Environmental Assessment Method Plus, BEAM Plus) for all campus new buildings, which included restriction of runoff from campus construction sites. Members should strive to preserve the natural environment by protecting land and aquatic ecosystems as summarized in Chapter 18 (Resource Conservation and Environmental Preservation).

All liquid effluents from the University laboratories, office areas and staff quarters enter the HKUST sanitary sewer system. The standards that pertain to these effluents are set by the Environmental Protection Department and apply to all sewers leading into government sewage treatment plants. HKUST is licensed by the EPD to use the sewage system leading to the Tseung Kwan O sewage treatment plant and must conform to the terms and conditions of the license. Monthly sampling of the sewage waste stream is conducted by HSEO at designated monitoring points. These samples are analyzed for all the parameters required by the license. The results of the laboratory analyses are provided to the EPD in regular reports. Unless otherwise specified, hazardous materials must not be disposed into the sewer system. Details of the HKUST hazardous material management scheme are summarized in Chapter 16 (Hazardous Waste Management).

The legal conditions that govern liquid effluent discharged into drainage and sewerage systems, and inland and coastal waters of Hong Kong are given in the Hong Kong Water Pollution Control Ordinance, Cap 358, S21. Details of the ordinance are summarized in the Technical Memorandum on Effluent Standards issued by the Secretary for Planning, Environment and Lands under Section 21(1) of the Water Pollution Control (Amendment) Ordinance 1990.

 

B. Hong Kong Regulations

I. Standards for Effluent Discharged to Foul Sewers

HKUST obtained a licence to discharge institutional trade effluent into the public sewer according to Water Pollution Control Ordinance (CAP. 358), Section 20. EPD specified a set of comprehensive Limitations on Discharge, including upper limits of flow rate, pH (a range), temperature, Suspended Solids, Settleable Solids, 5 day Biological Oxygen Demand, Chemical Oxygen Demand, Oil & Grease, and a range of toxic metals (including Arsenic, Chromium, Mercury, Cadmium, selenium, Lead, etc), Cyanide, Phenols, Sulphide, Sulphate, Total Phosphorus, Total Nitrogen, Surfactants (total) and Total Residual Chlorine.

The license also states that the sewer discharge shall not contain prohibited substances including Polyaromatic hydrocarbons (PAH), Polychlorinated biphenyls (PCB), fumigant, pesticide toxicants, radioactive substances, chlorinated hydrocarbons, flammable or toxic solvents, petroleum oil or tar, calcium carbide; any substance likely to damage the sewer or to interfere with any of the treatment processes, or to be harmful to the health and safety of any personnel engaged in the operation or maintenance of a sewerage system…or the waters of Hong Kong.  

The Authority does not allow dilution as a means of meeting effluent standards. Dilution lowers the concentration of waste by increasing the volume, but the total mass of waste, and thus the loading on the receiving waters and their biota, do not change.

 

II. Standards for Discharge from the Seawater Pump House

A separate license to permit HKUST to draw, use and discharge seawater back into the Port Shelter Water Control Zone was granted under Section 20 of the Water Pollution Control Ordinance. The license permits use of the seawater in the heat exchange system of the HKUST seawater pump house and allows treatment of the water by chlorination.

A different set of Limitations on Discharge was specified by EPD. This includes upper limits of Flow Rate, Temperature, Total Residual Chlorine and concentration of an approved biocide to prevent fouling of the seawater pumping system.

A list of prohibited substances in seawater effluent similar to those in wastewater is also specified by the license.

As with waste-water, the Authority does not allow dilution as a means of meeting effluent standards. That would cause excessive loading on the receiving waters and their biological systems.

 

III. Standards for Storm Water Drains

Most storm water drains discharge directly into inland or coastal waters. The Authority will not normally allow discharge of effluent to them. If an exception is made, effluent must meet the standards for the next receiving waters downstream. HKUST has waters that discharge into storm drains from runoff during rain storms from buildings, grounds and roads. Water draining from the roof of the academic buildings, where many exhaust ducts ventilate, also goes into storm water drains.

 

C. Practice on Effluent at HKUST

Because of the legal conditions governing the waste water stream from HKUST, students, technicians and researchers must be careful to avoid putting any solid or liquid chemical waste into the sinks that lead to the sanitary sewer system. Guidelines for good hazardous waste practice are given in Chapter 16. From there it can be seen that only simple alkalis and acids that have been neutralized to the pH range of 6-10 can be disposed into the sewer system. All other materials should be disposed of by appropriate hazardous waste procedures (see Chapter 16, Hazardous Waste Management).

Strict guidelines also control the cooling sea water used by HKUST. Chlorination to prevent growth of marine biota within the liquid conduit system is permitted in the licensing agreement as is the periodic use of an EPD registered biocide in the intake system to prevent proliferation of marine growth that would restrict the water intake.

In the case of each waste stream, HSEO conducts regular monitoring and complete chemical analysis of samples to verify compliance with EPD regulations. Records of such monitoring are provided to the EPD for review and are kept on file by HSEO. HSEO also conducts periodic evaluation of the sewage line in the tunnel to Tseung Kwan O and measures stream flow in the pipe at an access point in the tunnel. Periodic EPD inspections of the pipe and verification of the flow are hosted by HSEO.

All campus construction and maintenance work, whether done by in-house staff or contractors, must follow university requirements of minimizing surface runoff, and prohibition of discharge of dirty water into storm water drains.