Chemical Technology May 2016

Veolia pilots a process to optimise biogas production in Durban

Veolia’s scope of work for eThekwini Mu- nicipality included the supply, construction and commissioning of flow tanks, primary settling tanks, thickeners and digesters, as well as suction and delivery pipework, pumps, electrical power and control instru- mentation for the digestion plant. Veolia was also responsible for the mechanical and electrical design of the plant. Because of the varying waste

raw sewage will be pumped to two primary settlement tanks, in proportion to the flow- rate of the sewer feeding the tank. The primary settlement tanks form the starting point of a two-train treatment process. Raw sewage extracted from the Chatsworth sewer will feed train one, while the Jacobs and Badulla sewers will provide the feed for the second process train. Underflow from the primary settlement tanks will be transferred to thickeners, with each one receiving about 2,5 m 3 /day in intermittent feeds. Settled sludge from the thickener underflow will periodically be drawn off and fed into the 10 m 3 digesters. The biogas generated during this digestion phase will pass through a flow meter, gas analyser and a flame arrestor before being blown off into the atmosphere. The success of the pilot trial will be mea- sured according to the effective generation of this biogas via the anaerobic digestion relative to the wastewater feed flow rate from the different sources. For more information contact: Herbert Kleinhans, Project Engineer, Veolia Water Technologies South Africa on tel: +27 21 870 2752, or email herbert.kleinhans@veolia.com

Veolia Water Technologies, South Africa (Veolia) recently installed an anaerobic digestion pilot plant at eThekwini Water & Sanitation’s Southern Wastewater Treat- ment Plant in Merebank, Durban. The pilot trial is designed to test the digestibility of the domestic and industrial waste received by the plant. The plant was commissioned in the first quarter of 2016.

FOCUS ON WATER TREATMENT

composition and feed rates to the plant, piloting quality-specific treatment processes was re- quired to confirm the efficacy of the anaerobic digestion process to generate biogas from the cur- rent wastewater feed. The plant will concentrate sludge via settling and thick- ening followed by anaerobic digestion. Raw domestic and industrial sewage extracted for three sewers (Chatsworth, Ba- dulla and Jacobs) feeding the Municipal Wastewater Treatment Plant will be fed into three flow tanks (one tank for each inlet line) at a continuous flowrate of approximately 14 m 3 /h. From these flow tanks, 200 m 3 /day of

The sludge digestion pilot plant under construction, show- ing the two primary settling tanks in the foreground, two anaerobic digesters in the background and two thickener vessels (partially obscured) in centre of the plant.

Safe water guaranteed with new colorimetric analysing system Liquiline SystemCA80NO, the new colorimet- ric analysing system from Endress+Hauser, offers precise online monitoring of nitrite in drinking water, mineral water and raw water for food production. It enables plant manag- ers to comply with stipulated limit values and deliver detailed documentation.

Liquiline SystemCA80NO offers optimum support for manufacturers. It uses the stan- dardised colorimetric naphthylaminemethod following ISO 6777 and DIN EN 26777 — ensuring consistent comparability to lab measurements. The analyser also features detailed logbooks that provide continuous documentation of the nitrite values and en- able plant managers to prove compliance to water authorities. In drinking water treatment, dissolved nitrate is reduced to molecular nitrogen through a series of intermediate products. Liquiline System CA80NO monitors this denitrification process online and delivers measured values fast — helping to optimise the control of carbon dioxide dosing. It also supports plant operators in handling process disturbances promptly by advanced diagnos-

tics via remote access. The analytical system increases the safety of the denitrification process. Operating costs of a colorimetric analy- ser are dependent on the consumption of reagents and calibration standards over its lifetime. The Liquiline System is designed with highly precise dispensers for reagent dosing and an efficient cooling system. This guarantees reduced consumption and in- creased lifetime of the calibration standard. Automatic cleaning and calibration func- tions ensure that the analyser and its sample preparation and reagents work reliably and without manual intervention over a longer period of time. Maintenance tasks can be

carried out easily and with minimal tools, reducing maintenance costs and increasing process uptime. For more information contact: Jan Swart, Product Manager: Analytics on tel: +27 11 262 8000; email Jan.Swart@za.endress.com; or go to http://bit.ly/23gKM9C or www.za.endress.com

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Chemical Technology • May 2016