Luận Văn Thiết kế trạm XLNT sinh hoạt khu dân cư P. Phước Hòa, Tp. Tam Kỳ

LỜI MỞ ĐẦU
1. Đặt vấn đề.
Môi trường và những vấn đề liên quan đến môi trường là đề tài được quan tâm nhất trong kế hoạch phát triển bền vững của bất kỳ quốc gia nào trên thế giới. Trái đất – ngôi nhà chung của chúng ta đang bị đe dọa bởi sự suy thoái và cạn kiệt dần tài nguyên, ô nhiễm. Nguồn gốc của mọi sự biến đổi về môi trường trên thế giới ngày nay do các hoạt động kinh tế - xã hội. Các hoạt động này, một mặt cải thiện
chất lượng cuộc sống con người và môi trường, mặt khác lại mang lại hàng loạt các vấn đề như: khan hiếm, cạn kiệt tài nguyên thiên nhiên, ô nhiễm và suy thoái chất lượng môi trường khắp nơi trên thế giới. Trong giai đoạn hiện nay, khi mà nền kinh tế của nước ta có những bước phát triển mạnh mẽ và vững chắc, đời sống của người dân ngày càng được nâng cao thì vấn đề môi trường lại trở nên cấp thiết hơn bao giờ hết. Trong đó các vấn đề về nước được quan tâm nhiều hơn cả, các biện pháp để bảo vệ môi trường sống, bảo vệ nguồn nước mặt, nước ngầm không bị ô nhiễm do các hoạt động sinh hoạt và sản xuất của con người là thu gom và xử lý nước thải. Nước thải sau xử lý sẽ đáp ứng được các tiêu chuẩn thải vào môi trường cũng như khả năng tái sử dụng nước sau xử lý.
Hiện nay, việc thu gom và xử lý nước thải là yêu cầu không thể thiếu được của vấn đề vệ sinh môi trường, nước thải ra ở dạng ô nhiễm hữu cơ, vô cơ cần được thu gom và xử lý trước khi thải ra môi trường. Điều này được thực hiện thông qua hệ thống cống thoát nước và xử lý nước thải đô thị. Tuy độc lập về chức năng nhưng cả hai hệ thống này cần hoạt động đồng bộ. Nếu hệ thống thu gom đạt hiệu quả
nhưng hệ thống xử lý không đạt yêu cầu thì nước sẽ gây ô nhiễm khi được thải trở lại môi trường. trong trường hợp ngược lại, nếu hệ thống xử lý nước thải được thiết kế hoàn chỉnh nhưng hệ thống thoát nước không đảm bảo việc thu gom vận chuyển nước thải thì nước thải cũng sẽ phát thải ra môi trường mà chưa qua xử lý. Chính vì thế, việc đồng bộ hóa và phối hợp hoạt động giữa hệ thống thoát nước và hệ thống xử lý nước thải của một đô thị, một khu dân cư là hết sức cần thiết vì hai hệ thống này tồn tại với mối quan hệ hữu cơ mật thiết với nhau.
MỤC LỤC
Trang
LỜI MỞ ĐẦU.
1. Đặt vấn đề . ······························································································· 1
2. Mục tiêu của luận văn ···················································································· 2
3. Nội dung của luận văn ···················································································· 2
4. Phương pháp thực hiện . ················································································· 2
CHƯƠNG 1: GIỚI THIỆU SƠ LƯỢC VỀ KHU DÂN CƯ TRƯỜNG THẠNH
1.1. Đặc điểm tự nhiên . ···················································································· 3
1.1.1. Vị trí địa lý . ·························································································· 3
1.1.2. Địa hình . ····························································································· 4
1.1.3. Địa chất . ······························································································ 4
1.1.4. Khoáng sản ···························································································· 4
1.1.5. Sông ngoài···························································································· 5
1.1.6. Khí hậu và mưa . ····················································································· 5
1.1.7. Tài nguyên đất rừng . ················································································ 6
1.2. Sơ lược về kinh tế - xã hội . ··········································································· 7
1.2.1. Dân số ································································································· 7
1.2.2. Kinh tế .······························································································· 7
1.2.3. Giáo dục .····························································································· 8
1.2.4. Y tế ···································································································· 8
1.3. Các nguồn gây ô nhiễm môi trường và biện pháp kỹ thuật bảo vệ môi trường ···················· 8
1.3.1. Hiện trạng môi trường tại khu dân cư . ····························································· 9
1.3.2. Biện pháp kỹ thuật bảo vệ môi trường . ··························································· 10
1.3.2.1. Môi trường nước . ················································································ 11
1.3.2.2. Môi trường khí ···················································································· 11
1.3.2.3. Chất thải rắn và chất thải nguy hại . ····························································· 11
CHƯƠNG 2: TỔNG QUAN CÁC PHƯƠNG PHÁP XỬ LÝ NƯỚC THẢI
2.1.Phương pháp xử lý cơ học . ··········································································· 12
2.1.1 Song chắn rác và lưới chắn rác . ···································································· 12
2.1.2. Bể lắng cát ··························································································· 15
2.1.3. Bể tách dầu mỡ .···················································································· 18
2.1.4. Bể điều hòa . ························································································ 19
2.1.5. Bể lắng . ····························································································· 19
2.1.6. Bể lọc ································································································ 21
2.2. Phương pháp xử lý hóa học ·········································································· 22
2.2.1. Phương pháp trung hoà . ··········································································· 23
2.2.2. Phương pháp đông tụ và keo tụ . ·································································· 23
2.2.3. Phương pháp ozon hoá . ············································································ 25
2.2.4. Phương pháp điện hoá học ········································································· 25
2.2.5. Oxy hóa khử . ······················································································· 25
2.2.6. Phương pháp quang xúc tác .······································································ 26
2.3 Phương pháp xử lý hóa lý ············································································· 27
2.3.1. Tuyển nổi . ·························································································· 27
2.3.2. Trích ly ······························································································ 28
2.3.3. Hấp phụ ······························································································ 28
2.3.4. Chưng bay hơi . ····················································································· 29
2.3.5. Trao đổi ion . ························································································ 29
2.3.6. Tách bằng màng ····················································································· 30
2.4. Phương pháp xử lý sinh học ·········································································· 30
2.4.1 Công trình xử lý trong điều kiện tự nhiên . ······················································· 30
2.4.1.1. Ao hồ sinh học (Ao hồ ổn định nước thải) ······················································ 30
2.4.1.2. Phương pháp xử lý qua đất ······································································ 32
2.4.2 Các công trình xử lý hiếu khí nhân tạo . ··························································· 33
2.4.2.1. Bể phản ứng sinh học hiếu khí – Aeroten . ····················································· 34
2.4.2.2. Các công trình xử lý sinh học kị khí .··························································· 41
2.5. Phương pháp khử trùng . ············································································· 44
2.6. Xử lý cặn ······························································································ 46
2.7. Sơ lược về các vi sinh vật trong việc xử lý nước thải . ············································ 47
CHƯƠNG 3: CƠ SỞ LỰA CHỌN PHƯƠNG ÁN XỬ LÝ NƯỚC THẢI
3.1. Thành phần nước thải sinh hoạt . ···································································· 54
3.2 Các chỉ tiêu cơ bản về chất lượng nước thải sinh hoạt ·············································· 56
3.2.1 Các chỉ tiêu lí học . ·················································································· 56
3.2.2 Các chỉ tiêu hóa học và sinh hóa ···································································· 57
3.3. Xác định các thông số tính toán .···································································· 61
3.3.1. Xác định lưu lượng tính toán nước thải khu dân cư Phường Trường Thạnh ··················· 61
3.3.2 Xác định nồng độ bẩn của nước thải . ······························································ 64
3.3.3. Xác định mức độ cần xử lý nước thải ····························································· 65
3.4. Đề xuất các phương án xử lý nước thải sinh hoạt ·················································· 66
CHƯƠNG 4: THIẾT KẾ HỆ THỐNG XỬ LÝ NƯỚC THẢI
4.1.Tính toán các công trình đơn vị xử lý nước thải . ··················································· 71
4.1.1. Phương án ··························································································· 71
4.1.1.1. Song chắn rác (SCR) .············································································ 71
4.1.1.3 Bể lắng cát thổi khí .·············································································· 78
4.1.1.4. Bể lắng đứng đợt I ················································································ 82
4.1.1.5. Bể lọc sinh học nhỏ giọt .········································································ 86
4.1.1.6. Bể lắng đứng đợt II . ············································································ 100
4.1.1.7. Bể tiếp xúc – khủ trùng ········································································· 104
4.1.1.8. Sân phơi bùn . ··················································································· 107
4.1.1.9. Công trình xả nước thải ra nguồn tiếp nhận . ················································· 109
4.1.2. Phương án 2 ························································································ 110
4.1.2.1. Bể điều hòa . ····················································································· 110
4.1.2.2. Bể Aeroten ······················································································· 113
4.1.3. Phương án 3 ························································································ 122
4.1.3.1 Mương oxy hóa ··················································································· 122
4.2. Bố trí mặt bằng trạm xử lý nước thải và cao trình xây dựng các hạng mục . ··················· 127
4.2.1. Bố trí vị trí và mặt bằng trạm xử lý nước thải ·················································· 127
4.2.2. Cao trình xây dựng các hạng mục································································ 127
CHƯƠNG 5: DỰ TOÁN KINH PHÍ ĐẦU TƯ XÂY DỰNG
5.1. Vốn đầu tư cho từng hạng mục công trình phương án 1 ········································· 129
5.2. Vốn đầu tư cho từng hạng mục công trình phương án 2 ········································· 133
5.3. Vốn đầu tư cho từng hạng mục công trình phương án 3 ········································· 137
CHƯƠNG 6: QUẢN LÝ VẬN HÀNH
6.1. Vận hành hệ thống khi gặp sự cố . ································································· 144
6.2. Các sự cố thường gặp và cách khắc phục . ························································· 145
6.3. Công tác bảo trì và bảo dưỡng hệ thống . ·························································· 146
6.3.1. Hệ thống đường ống kỹ thuật và bể chứa ······················································· 146
6.3.2. Các thiết bị ························································································· 147
6.4. Một số vấn đề về an toàn lao động ································································· 148
6.4.1. Các qui định chung . ·············································································· 148
6.4.2. Các trang thiết bị bảo hộ cần thiết ······························································· 149
CHƯƠNG 7: KẾT LUẬN VÀ KIẾN NGHỊ
6.1. Kết luận . ····························································································· 150
6.2. Kiến nghị . ··························································································· 151
TÀI LIỆU THAM KHẢO ················································································ 152

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